Patent Application
20160153239
Not applicable.
Not applicable.
This section is intended to introduce selected aspects of the art, which may be associated with various embodiments of the present disclosure. This discussion is believed to assist in providing a framework to facilitate a better understanding of particular aspects of the present disclosure. Accordingly, it should be understood that this section should be read in this light, and not necessarily as admissions of prior art.
The present disclosure relates to the field of well completion. More specifically, the present disclosure relates to the completion and stimulation of a hydrocarbon-producing formation by the generation of small diameter boreholes from an existing wellbore using a hydraulic jetting assembly. The present disclosure further relates to the controlled generation of multiple lateral boreholes that extend many feet into a subsurface formation, in one trip.
In the drilling of an oil and gas well, a near-vertical wellbore is formed through the earth using a drill bit urged downwardly at a lower end of a drill string. After drilling to a predetermined bottomhole location, the drill string and bit are removed and the wellbore is lined with a string of casing. An annular area is thus formed between the string of casing and the formation penetrated by the wellbore. Particularly in a vertical wellbore, or the vertical section of a horizontal well, a cementing operation is conducted in order to fill or “squeeze” the entire annular volume with cement along part or all of the length of the wellbore. The combination of cement and casing strengthens the wellbore and facilitates the zonal isolation, and subsequent completion, of certain sections of potentially hydrocarbon-producing pay zones behind the casing.
Within the last two decades, advances in drilling technology have enabled oil and gas operators to economically “kick-off” and steer wellbore trajectories from a generally vertical orientation to a generally horizontal orientation. The horizontal “leg” of each of these wellbores now often exceeds a length of one mile. This significantly multiplies the wellbore exposure to a target hydrocarbon-bearing formation (or “pay zone”). For example, for a given target pay zone having a (vertical) thickness of 100 feet, a one mile horizontal leg exposes 52.8 times as much pay zone to a horizontal wellbore as compared to the 100-foot exposure of a conventional vertical wellbore.
In connection with the completion of the wellbore 4, several strings of casing having progressively smaller outer diameters have been cemented into the wellbore 4. These include a string of surface casing 6, and may include one or more strings of intermediate casing 9, and finally, a production casing 12. (Not shown is the shallowest and largest diameter casing referred to as conductor pipe, which is a short section of pipe separate from and immediately above the surface casing.) One of the main functions of the surface casing 6 is to isolate and protect the shallower, fresh water bearing aquifers from contamination by any wellbore fluids. Accordingly, the conductor pipe and the surface casing 6 are almost always cemented 7 entirely back to the surface 1.
The process of drilling and then cementing progressively smaller strings of casing is repeated several times until the well has reached total depth. In some instances, the final string of casing 12 is a liner, that is, a string of casing that is not tied back to the surface 1. The final string of casing 12, referred to as a production casing, is also typically cemented 13 into place. In the case of a horizontal completion, the production casing 12 may be cemented, or may provide zonal isolation using external casing packers (“ECP's), swell packers, or some combination thereof.
Additional tubular bodies may be included in a well completion. These include one or more strings of production tubing placed within the production casing or liner (not shown in
In some instances, the pay zone 3 is incapable of flowing fluids to the surface 1 efficiently. When this occurs, the operator may install artificial lift equipment (not shown in
As part of the completion process, a wellhead 5 is installed at the surface 1. The wellhead 5 serves to contain wellbore pressures and direct the flow of production fluids at the surface 1. Fluid gathering and processing equipment (not shown in
Within the United States, many wells are now drilled principally to recover oil and/or natural gas, and potentially natural gas liquids, from pay zones previously thought to be too impermeable to produce hydrocarbons in economically viable quantities. Such “tight” or “unconventional” formations may be sandstone, siltstone, or even shale formations. Alternatively, such unconventional formations may include coalbed methane. In any instance, “low permeability” typically refers to a rock interval having permeability less than 0.1 millidarcies.
In order to enhance the recovery of hydrocarbons, particularly in low-permeability formations, subsequent (i.e., after perforating the production casing or liner) stimulation techniques may be employed in the completion of pay zones. Such techniques include hydraulic fracturing and/or acidizing. In addition, “kick-off” wellbores may be formed from a primary wellbore in order to create one or more new directionally or horizontally completed boreholes. This allows a well to penetrate along the plane of a subsurface formation to increase exposure to the pay zone. Where the natural or hydraulically-induced fracture plane(s) of a formation is vertical, a horizontally completed wellbore allows the production casing to intersect, or “source,” multiple fracture planes. Accordingly, whereas vertically oriented wellbores are typically constrained to a single hydraulically-induced fracture plane per pay zone, horizontal wellbores may be perforated and hydraulically fractured in multiple locations, or “stages,” along the horizontal leg 4c.
The desired density of perforated and fractured intervals within the pay zone 3 along the horizontal leg 4c is optimized by calculating:
The additional costs in drilling and completing horizontal wells as opposed to vertical wells is not insignificant. In fact, it is not at all uncommon to see horizontal well drilling and completion (“D & C”) costs top multiples (double, triple, or greater) of their vertical counterparts. Depending on the geologic basin, and particularly the geologic characteristics that govern such criteria as drilling penetration rates, required drilling mud rheology, casings design and cementation, etc., significant additional costs for drilling and completing horizontal wells include those involved in controlling the radius of curvature of the kick-off, and guidance of the bit and drilling assembly (including MWD and LWD technologies) in initially obtaining, then maintaining the preferred at-or-near horizontal trajectory of the wellbore 4 within the pay zone 3, and the overall length of the horizontal section 4c. The critical process of obtaining wellbore isolation between frac stages, as with additional cementing and/or ECP's, are often significant additions to the increased completion expenses, as are costs for “plug-and-perf” or sleeve or port (typically ball-drop actuated) completion systems.
In many cases, however, the greatest single cost in drilling and completing horizontal wells is the cost associated with pumping the multiple hydraulic fracture treatments themselves. It is not uncommon for the sum of the costs of a given horizontal well's hydraulic fracturing treatments to approach, or even exceed, 50% of its total drilling and completion cost.
Crucial to the economic success of any horizontal well is the achievement of satisfactory hydraulic fracture geometries within the pay zone being completed. Many factors can contribute to the success or failure in achieving the desired geometries. These include the rock properties of the pay zone, pumping constraints imposed by the wellbore's construction and/or surface pumping equipment, and characteristics of the fracturing fluids. In addition, proppants of various mesh (sieve) sizes are typically added to the fracturing mixture to maintain the hydraulic pressure-induced fracture width in a “propped open” state, thereby increasing the fracture's conductive capacity for producing hydrocarbon fluids.
Often, in order to achieve desired fracture characteristics (fracture width, fracture conductivity, and particularly, fracture half-length) within the pay zone, an overall fracture height must be created that considerably exceeds the boundaries of the pay zone. Fortunately, vertical out-of-zone fracture height growth is usually confined to a few multiples of the overall pay formation's thickness (i.e., ten's or hundreds' of feet), and thereby cannot pose a threat to contamination of much shallower fresh water sources, almost always separated from the pay zone by multiple thousands of feet of rock formations. See K. Fisher and N. Warpinski, “Hydraulic Fracture-Height Growth: Real Data,” SPE Paper No. 145,949, SPE Annual Technical Conference and Exhibit, Denver Colo. (Oct. 30-Nov. 2, 2012).
Nevertheless, this increases the amount of fracturing fluid and proppant needed at the various “frac” stages, and further increases the required pumping horsepower. It is known that for a typical fracturing job, significant volumes of fracturing fluids, fluid additives, proppants, hydraulic (“pumping”) horsepower (or, “HHP”), and their correlative costs are expended on non-productive portions of the fractures. This represents a multi-billion dollar problem each year within the U.S. alone.
Further complicating the planning of a horizontal wellbore are the uncertainties associated with fracture geometries within unconventional reservoirs. Many experts believe, based on analyses of real-time data from both tilt meter and micro-seismic surveys, that fracture geometries in less permeable, and particularly, more brittle, unconventional reservoirs can yield highly complex fracture geometries. That is, as opposed to the relatively simplistic bi-wing elliptical model perceived to fit most conventional reservoirs (and as shown in the idealistic rendition in
In most cases, far-field fracture length and complexity is deemed detrimental (rather than beneficial) due to excessive fluid leak-off and/or reduced fracture width that can cause early screen-outs. Hence, whether fracture complexity (or, the lack thereof) enhances or reduces the SRV that the fracture network will enable the wellbore to drain is typically determined on a case-by-case (e.g., reservoir-by-reservoir) basis.
Thus, it is desirable, particularly in horizontal wellbore completions for tight reservoirs, to obtain greater control over the geometric growth of the primary fracture network extending perpendicularly outward from the horizontal leg 4c. It is further desirable to extend the length of the fracture network azimuth without significantly trespassing the horizontal pay zone 3 boundaries. Further, it is desirable to decrease the well density required to drain a given reservoir volume by increasing the effectiveness of the fracture network between wellbores through the use of two or more hydraulically-jetted mini-laterals along a horizontal leg. Still further, it is desirable to provide this guidance, constraint, and enhancement of SRV's by the creation of one or more mini-lateral boreholes as a replacement of conventional casing portals provided by the use of conventional completion procedures requiring perforations, sliding sleeves, and the like.
Accordingly, a need exists for a downhole assembly having a jetting hose and a whipstock, whereby the assembly can be conveyed into any wellbore interval of any inclination, including an extended horizontal leg. A need further exists for a hydraulic jetting system that provides for substantially a 90° turn of the jetting hose opposite the point of a casing exit, preferably utilizing the entire casing inner diameter as the bend radius for the jetting hose, thereby providing for the maximum possible inner diameter of jetting hose, and thus providing the maximum possible hydraulic horsepower to the jetting nozzle. A need further exists for a system that includes a whipstock deployable on a string of coiled tubing, wherein the whipstock can be reoriented in discreet, known increments, and not depend upon pipe rotation at the surface translating downhole.
Additional needs exist that, in certain embodiments, are addressed herein. A need exists for improved methods of forming lateral wellbores using hydraulically directed forces, wherein the desired length of jetting hose can be conveyed even from a horizontal wellbore. Further, a need exists for a method of forming mini-lateral boreholes off of a horizontal leg that assist in confining subsequent SRV's up to, but not significantly beyond, pay zone boundaries. Still further, a need exists for a method by which a whipstock and jetting hose can be conveyed and operated with hydraulic and/or mechanical push forces that enable movement of the jetting nozzle and connected hose into the formation, retrieved, re-oriented and re-deployed and re-operated multiple times at as many parent wellbore depths and mini-lateral azimuth orientations as desired, to generate multiple mini-lateral bore holes within not only vertical, but highly directional and even horizontal portions of wellbores in a single trip. A need further exists to be able to convey the jetting hose in an uncoiled state, such that the bend radius within the production casing and along the whipstock is the tightest bending constraint the hose must satisfy.
A need further exists for a method of hydraulically fracturing mini-lateral boreholes jetted off of the horizontal leg of a wellbore immediately following lateral borehole formation, and without the need of pulling the jetting hose, whipstock, and conveyance system out of the parent wellbore. A need further exists for a method of contouring clusters of lateral boreholes' paths based upon real-time analysis of geophysical (micro-seismic and/or tiltmeter and/or ambient micro-seismic) descriptions of resultant SRV development (or lack thereof) from pumping a given stimulation (frac) stage. Additionally, a need exists for a method of optimizing the recompletion of an existing horizontal well by optimizing the placement and contouring of new lateral borehole clusters/stimulation stages based upon the performance (or, more specifically, non-performance such as observed by production logging or permanent ambient micro-seismic installations) of existing conventional perforation clusters and their respective stimulation stage's SRV. Stated another way, a need exists for a method of remotely controlling the erosional excavation path of the jetting nozzle and connected hydraulic hose, such that a lateral borehole, or multiple lateral borehole “clusters,” can be contoured to best control the SRV geometry resulting from a subsequent stimulation treatment stage.
The systems and methods described herein have various benefits in the conducting of oil and gas well completion activities. In the present disclosure, a method of forming a lateral borehole in a pay zone is first claimed. The pay zone exists within an earth subsurface. In one embodiment, the method first comprises determining a depth of the pay zone in a subsurface formation. The pay zone defines a rock matrix that has been identified as holding, or at least potentially holding, hydrocarbon fluids or organic-rich rock. In one aspect, the method also includes determining a thickness of the pay zone.
The method additionally includes forming a wellbore within the pay zone. In a preferred embodiment, the wellbore has deviated section or, more preferably, is completed horizontally. In these instances, forming the wellbore means forming a parent wellbore at an angle offset from vertical, or even forming a wellbore along a generally horizontal plane.
The method further includes conveying a hydraulic jetting assembly into the wellbore on a working string. Preferably, the working string is a string of coiled tubing having a sheath for holding electrical wires and, optionally, fiber optic data cables.
The downhole hydraulic jetting assembly is useful for jetting multiple lateral boreholes from an existing parent wellbore into the subsurface formation. The assembly is basically comprised of two synergetic systems:
In the case of a cased wellbore, a window is formed through the casing using the jetting hose and connected nozzle, followed by the formation of a lateral borehole out into a hydrocarbon-bearing pay zone. The configuration and operation of these two synergetic systems provide that the whipstock may be re-oriented and/or re-located, and the jetting hose re-deployed into the casing and re-retrieved, for the jetting of multiple casing exits and lateral boreholes in the same trip.
As noted, the internal system comprises a jetting hose having a proximal end and a distal end. A fluid inlet resides at the proximal end, while a jetting nozzle is disposed at the distal end. Preferably, a power supply such as a battery pack resides at the proximal end for providing power to electrical components of the jetting assembly.
The external system comprises a pair of tubular bodies. These represent an outer conduit and an inner conduit. The outer conduit has an upper end configured to be operatively attached to the working string, or “tubing conveyance medium,” for running the jetting hose assembly into the production casing, a lower end, and an internal bore there between. The inner conduit resides within the bore of the outer conduit and serves as a jetting hose carrier. The jetting hose carrier slidably receives the jetting hose during operation.
A micro-annulus is formed between the jetting hose and the surrounding jetting hose carrier. The micro-annulus is sized to prevent buckling of the jetting hose as it slides within the jetting hose carrier during operation of the assembly. The micro-annulus is further configured to allow the operator to control the amount and flow direction of hydraulic fluid between the jetting hose and the surrounding inner conduit, which then converts to a fluid force that can either: (1) maintain the jetting hose in a taught configuration as it is urged downstream; or (2) urge the jetting hose in an upstream direction as it is retrieved back into the inner conduit.
The jetting hose assembly also includes a whipstock member. The whipstock member is disposed below the lower end of the outer conduit. The whipstock member includes a concave face for receiving and directing the jetting nozzle and connected hose during operation of the assembly.
The jetting hose assembly is configured to (i) translate the jetting hose out of the jetting hose carrier and against the arcuate whipstock face by a translation force to a desired point of wellbore exit, (ii) upon reaching the desired point of wellbore exit, direct jetting fluid through the jetting hose and the connected jetting nozzle until an exit is formed, (iii) continue jetting along an operator's designed geo-trajectory forming a lateral borehole into the rock matrix within the pay zone, and then (iv) pull the jetting hose back into the jetting hose carrier after a lateral borehole has been formed to allow the location of the whipstock device within the wellbore to be adjusted.
In one aspect, the whipstock is configured so that a face of the whipstock provides a bend radius for the jetting hose across the entire wellbore. In the case of a cased hole, the jetting hose will bend across the entire inner diameter of the production casing. Thus, the hose contacts the production casing on one side, bends along the face of the whipstock, and then extends to a casing exit on an opposite side of the production casing. This jetting hose bend radius spanning the entire I.D. of the production casing provides for utilization of the greatest possible diameter of jetting hose, which in turn provides for maximum delivery of hydraulic horsepower through the jetting hose to the jetting nozzle.
The external system is configured such that it contains, conveys, deploys, and retrieves the jetting hose of the internal system in such a way as to maintain the hose in an uncoiled state. Thus, the minimum bend radius that the hose must satisfy is that of the bend radius within the production casing, along the whipstock face, at the point of a desired casing exit. In addition, the coiled tubing-based conveyance of these synergetic internal/external systems provides for simultaneous running of other conventional coiled tubing tools in the same tool string. These may include a packer, a mud motor, a downhole (external) tractor, logging tools, and/or a retrievable bridge plug residing below the whipstock member.
Returning to the method at hand, the method also comprises setting the whipstock at a desired first casing exit location along the wellbore. The face of the whipstock bends the jetting hose substantially across the entire inner diameter of the wellbore while the jetting hose is translated out of the jetting hose carrier. The method additionally includes translating the jetting hose out of the jetting hose carrier to advance the jetting nozzle to the face of the whipstock. The method then includes injecting hydraulic jetting fluid through the jetting hose and connected jetting nozzle, thereby excavating a lateral borehole within the rock matrix in the pay zone.
The method also includes further injecting the jetting fluid while further translating the jetting hose and connected jetting nozzle through the jetting hose carrier and along the face of the whipstock. In this way, a first lateral borehole that extends at least 5 feet from the horizontal wellbore is formed.
In the present disclosure, a unique electric-driven, rotatable jetting nozzle is optionally provided for the external system. The nozzle can emulate the hydraulics of conventional hydraulic perforators, thereby precluding the need for a separate run with a milling tool to form a casing exit. The nozzle optionally includes rearward thrusting jets about the body to enhance forward thrust and borehole cleaning during mini-lateral formation, and to provide clean-out and, possibly, borehole expansion, during pull-out.
Within the external system, regulation of the hydraulic forces of both: (a) the jetting fluid's hydraulic force that urges the internal hose system downstream; and, (b) the hydraulic fluid's hydraulic force that urges the hose system back upstream, are both controlled with valves at the top and base of the carrier system, and seal assemblies both at the top of the jetting hose and at the base of the carrier system. In addition, the external system may include an internal tractor system that provides a mechanical force for selectively urging the jetting hose upstream or downstream.
It is observed that known jetting systems generally rely only on “slack-off” weight of a continuous coiled tubing and/or jetting hose string for “push” force. However, this source of propulsion would be quickly dissipated by helical buckling (e.g., due to friction forces between the jetting hose and wellbore tubulars) in a highly directional or horizontal wellbore. Once the point of helical buckling is reached, supplemental push force from additional slack-off of the string tied to the surface is no longer attainable. The “can't-push-a-rope” limitation of other systems is uniquely overcome herein by the combination of hydraulic and mechanical (tractor) forces, enabling the formation of mini-laterals off of an extended-reach horizontal wellbore.
The hydraulic jetting assembly herein is able to generate lateral bore holes in excess of 10 feet, or in excess of 25 feet, and even in excess of 300 feet, depending on the length of the jetting hose and its jetting hose carrier. Length of penetration and penetration rate itself may also be influenced by the hydraulic jetting-resistance qualities of the host rock. These jetting-resistance qualities may include compressive strength, pore pressure, cementation, and other features inherent to the lithology of the host rock matrix. In any instance, the lateral boreholes may have a diameter of about 1.0″ or greater and may be formed at penetration rates much higher than any of the systems that have preceded it that have in common completing a 90° turn of the jetting hose within the production casing.
The present system will have the capacity to generate lateral boreholes from portions of horizontal and highly directional parent wellbores heretofore thought unreachable. Anywhere to which conventional coiled tubing can be tractored within a cased wellbore, lateral boreholes can now be hydraulically jetted. Similarly, superior efficiencies will be captured as multiple intervals of lateral boreholes are formed from a single trip. Wherever satisfactory fracturing hydraulics (pump rates and pressures) are attainable via the coiled tubing-casing annulus, the entire horizontal leg of a newly drilled well may be “perforated and fractured” in stages without need of frac plugs, sliding sleeves or dropped balls.
In one embodiment, multiple lateral boreholes and, optionally, side mini-lateral boreholes, together form a network or cluster of ultra-deep perforations in the rock matrix. Such a network may be designed by the operator to optimally drain a pay zone. Preferably, the lateral boreholes extend away from the parent wellbore at a normal, or right, angle, and extend to an upper or lower boundary of the pay zone. Other angles may be used as well to take advantage of the richest portions of a pay zone. In any respect, the method may then include producing hydrocarbons. Where multiple boreholes are formed at different orientations from the wellbore and at different depths, hydrocarbons may be produced from a network of lateral boreholes. Moreover, the operation may choose to conduct subsequent formation fracturing operations from the lateral boreholes, thereby further extending the SRV.
In one aspect, geometries of lateral boreholes and side min-lateral boreholes are customized within the host pay zone. The boreholes can then optimally receive a subsequent stimulation (particularly, hydraulic fracturing) treatments. This, in turn, enables optimization of the resultant Stimulated Reservoir Volume (“SRV”) to be obtained from each pumping stage. During fracturing, the operator may receive real-time geophysical data, such as micro-seismic, tiltmeter, and/or ambient micro-seismic data, indicative of the effectiveness of formation treatments and SRV development. In one aspect, during a horizontal wellbore's completion or re-completion, real-time customization of the next cluster's lateral borehole geometries may be conducted prior to pumping a next stage.
In one embodiment, hydrocarbons are produced from the wellbore for a period of time before the lateral borehole is formed. Thus, a novel “re-fracturing” method is provided.
In a variation, the method comprises:
In another alternate embodiment, the method further comprises:
In this embodiment, each of the first and second lateral boreholes may have an internal diameter of between about 0.4 and 2.5 inches. In one aspect, the second lateral borehole is offset from the first lateral borehole by between 10-degrees and 180-degrees. The method may then further include producing hydrocarbon fluids from the first and second lateral boreholes together.
In another alternate embodiment, the method further comprises:
In this embodiment, the first and second lateral boreholes may be separated by about 5 to 200 feet. Preferably, each of the first and second lateral boreholes is at least 25 feet in length and, more preferably, at least 100 feet in length.
In any of the above embodiments, the method may further comprise injecting fracturing fluids through an annulus formed between the external conduit and the surrounding production casing, and injecting the fracturing fluids into one or more lateral boreholes at an injection pressure sufficient to part the rock matrix in the pay zone. The hydraulic jetting assembly may further comprise a packer or a retrievable bridge plug disposed below the whipstock member, and the method may further comprise setting the packer or bridge plug before injecting a fracturing fluid. Alternatively or in addition, an acid treatment may be washed down through the annular region and into the lateral boreholes, preferably prior to fracturing. Given the system's ability to controllably “steer” a jetting nozzle and thereby contour the path of a lateral borehole (or, “clusters” of boreholes), fracturing fluids can be more optimally “guided” and constrained within a pay zone.
In any of the above methods, the translation force used in moving the jetting hose out of the jetting hose carrier may be a hydraulic force. The jetting hose and associated jetting hose carrier are preferably each at least 10 feet in length and, more preferably, at least 50 feet in length.
In one embodiment, the jetting hose assembly further comprises a main control valve. The main control valve is disposed proximate the upper end of the outer conduit, and is movable between a first position and a second position. In the first position the main control valve directs jetting fluids pumped into the wellbore into the jetting hose, while in the second position the main control valve directs hydraulic fluid pumped into the wellbore into the annular region formed between the jetting hose carrier and the surrounding outer conduit. Placement of the main control valve in its first position allows an operator to pump jetting fluids into the working string, through the main control valve, and against the upper seal assembly in the micro-annulus, thereby pistonly pushing the jetting hose and connected nozzle downhole in an uncoiled state while directing jetting fluids through the nozzle. Placement of the main control valve in its second position allows an operator to pump hydraulic fluids into the working string, through the main control valve, into the annular region between the jetting hose carrier and the surrounding outer conduit, through the pressure regulator valve and into the micro-annulus, thereby pulling the jetting hose back up into the inner conduit in its uncoiled state.
In one preferred embodiment, the translation force comprises both the hydraulic force and a separate mechanical force. In this instance, the jetting hose assembly further comprises an internal tractor system residing downstream from the lower end of the outer conduit. The internal tractor system comprises an inner conduit portion defining a part of the jetting hose carrier for receiving the jetting hose, an outer conduit portion defining a part of the outer conduit, the outer conduit portion having a star-shaped profile defining a plurality of radially-disposed prongs, a wiring chamber housing electrical wires, data cables, or both within one of the plurality of prongs, and at least one pair of grippers residing within opposing prongs, with each gripper being configured to engage and mechanically move the jetting hose along the jetting hose carrier when rotatably actuated.
In one embodiment, the hydraulic jetting assembly further comprises a docking station located at an upper end of the external system. The docking station is configured to mate with the battery pack. The docking station having a micro-processor and is in communication with an operator at the surface by means of the electrical wires, the data cables or both of the coiled tubing. In this arrangement, the method may further comprise:
The docking station preferably also houses a micro-processor along with a micro-transmitter, a micro-receiver, an electrical current regulator, or combinations thereof. The docking station may be configured to transfer: (1) power to the battery pack, said power either originating from generation at the surface, or from generation by a mud turbine below the whipstock member, said power being transmitted via electrical wiring provided along the external system; and (2) data to and from the micro-transmitter and micro-receiver in the docking station, between one or more geo-spatial chips housed at or near the nozzle and the operator at the surface. The micro-transmitter housed in the battery pack is configured to wirelessly transmit the data received from the micro-receiver to a micro-receiver housed in the docking station. The docking station is configured to further transmit the data to a processor at the surface (i) wirelessly, (ii) via electrical wires bundled in the coiled tubing, or (iii) via data cables bundled in the coiled tubing.
In one arrangement, the method further comprises
In one arrangement, a longitudinal axis of the horizontal wellbore is oriented parallel to the plane of least principle stress of the rock matrix comprising the pay zone. In addition, the first lateral borehole is formed in a direction perpendicular to the plane of least principle stress of the rock matrix. Conducting a geo-mechanical analysis of the rock matrix may comprise creating a finite element mesh representing the pay zone, wherein the mesh defines a plurality of nodes representing points in space. Each point has potential displacement in more than one direction. The analysis may further involve predicting changes in the stress profile within the rock matrix as a result of the formation of the lateral boreholes.
In another arrangement, the downhole hydraulic jetting assembly and the methods herein operate in conjunction with a guidance system. The guidance system includes the use of at least three longitudinally oriented actuator wires connected to a distal end of the jetting nozzle. The actuator wires are equi-distantly spaced about the circumference of the jetting hose at its distal end, and are fabricated from a conductive material that contracts in response to electrical current. Differing amounts of electrical current directed through the actuator wires will induce a bending moment to orient the jetting nozzle in a desired direction. In this arrangement, the micro-processor is configured to control electrical current regulators feeding current to the respective actuator wires. This, in turn, controls a geo-orientation of the nozzle for directional hydraulic boring.
In one aspect of the guidance system, geo-location signals are sent by one or more geo-spatial chips residing along or near the nozzle. The geo-location signals are indicative of the location of the nozzle, its orientation, or both. The geo-location signals are transmitted as data from the geo-spatial chips to the micro-receiver in the battery pack. Signals may be sent via electrical wiring or data cables bundled in the jetting hose. The micro-transmitter housed in the battery pack's end cap is configured to wirelessly transmit the data received from the micro-receiver to a corresponding micro-receiver housed in the docking station. In addition, the docking station may be configured to further transmit the data to a processor at the surface. This geo-date may be sent wirelessly, via electrical wires bundled in the coiled tubing, or via data cables bundled in the coiled tubing.
Geo-trajectory instructions may likewise be sent from a control system residing either at the surface, or in the micro-processor residing in the docking station, downhole. The control system sends signals to one or more current regulators for regulating an amount of current to be sent to each individual actuator wire downhole. Contraction of each of the actuator wires is in direct proportion to an amount of electrical current each wire receives. The contraction, in turn, creates a bending moment, thereby enabling geo-steering of the nozzle according to a desired trajectory. In a preferred embodiment, the bending moment applied to the distal end of the jetting hose is controlled by an operator at the surface through the delivery of geo-trajectory signals sent to a micro-transmitter in the docking station.
So that the manner in which the present inventions can be better understood, certain illustrations, charts and/or flow charts are appended hereto. It is to be noted, however, that the drawings illustrate only selected embodiments of the inventions and are therefore not to be considered limiting of scope, for the inventions may admit to other equally effective embodiments and applications.
a is an axial, cross-sectional view of the bundled jetting hose of
a through 3G-1c present enlarged, cross-sectional views of the jetting nozzle of
a is an axial, cross-sectional view showing a basic nozzle body. The nozzle body includes a rotor and a surrounding stator.
b is a longitudinal, cross-sectional view of a jetting nozzle, taken across line C-C′ of
c is a longitudinal cross-sectional view of the jetting nozzle of
d is an axial, cross-sectional view of the jetting hose of
a and 3F-2b present longitudinal, cross-sectional views of the nozzle of
In
c is an axial, cross-sectional view of the nozzle of
a and 3F-3c provide longitudinal, cross-sectional views of the jetting nozzle of
In
b and 3F-3d show axial, cross-sectional views of the jetting nozzle correlative to
a is an axial, cross-sectional view showing a basic collar body for a jetting collar that can be placed within a length of jetting hose. The collar body again includes a rotor and a surrounding stator. The view is taken across line D-D′ of
b is a longitudinal, cross-sectional view of the jetting collar of
c is an axial, cross-sectional view of the jetting nozzle of
a is an axial, cross-sectional view of the coiled tubing conveyance medium of
a is an enlarged, perspective view of the crossover connection of
a is a cross-sectional view of the main control valve, taken across line G-G′ of
b is a perspective view of a sealing passage cover of the main control valve, shown exploded away from
a shows an axial, cross-sectional view of the main body of the jetting hose carrier section, taken along line H-H′ of
b is an enlarged view of a portion of the jetting hose carrier section of
a provides an axial, cross-sectional view of the jetting hose carrier section of
a is an enlarged, perspective view of the transition between lines I-I′ and J-J′ of
a is an axial, cross-sectional view of the internal tractor system of
b is an enlarged half-view of a portion of the internal tractor system of
a depicts a perspective view of the outer body transition between the internal tractor system to the upper swivel. This is a star-shape (L-L′) to a circle-shape (M-M′) transition of the outer body.
b provides an axial, cross-sectional view of the upper swivel of
a is an axial, cross-sectional view of the whipstock member, with a perspective view of sequential axial jetting hose cross-sections depicting its path downstream from the center of the whipstock member at line O-O′ to the start of the jetting hose's bend radius as it approaches line P-P′.
b depicts an axial, cross-sectional view of the whipstock member at line P-P′.
a provides an axial, cross-sectional view of a portion of the bottom swivel of
As used herein, the term “hydrocarbon” refers to an organic compound that includes primarily, if not exclusively, the elements hydrogen and carbon. Hydrocarbons generally fall into two classes: aliphatic, or straight chain hydrocarbons, and cyclic, or closed ring hydrocarbons, including cyclic terpenes. Examples of hydrocarbon-containing materials include any form of natural gas, oil, coal, and bitumen that can be used as a fuel or upgraded into a fuel.
As used herein, the term “hydrocarbon fluids” refers to a hydrocarbon or mixtures of hydrocarbons that are gases or liquids. For example, hydrocarbon fluids may include a hydrocarbon or mixtures of hydrocarbons that are gases or liquids at formation conditions, at processing conditions, or at ambient conditions. Hydrocarbon fluids may include, for example, oil, natural gas, condensate, coal bed methane, shale oil, shale gas, and other hydrocarbons that are in a gaseous or liquid state.
As used herein, the term “fluid” refers to gases, liquids, and combinations of gases and liquids, as well as to combinations of gases and solids, and combinations of liquids and solids.
As used herein, the term “subsurface” refers to geologic strata occurring below the earth's surface.
The term “subsurface interval” refers to a formation or a portion of a formation wherein formation fluids may reside. The fluids may be, for example, hydrocarbon liquids, hydrocarbon gases, aqueous fluids, or combinations thereof.
The terms “zone” or “zone of interest” refer to a portion of a formation containing hydrocarbons. Sometimes, the terms “target zone,” “pay zone,” or “interval” may be used.
As used herein, the term “wellbore” refers to a hole in the subsurface made by drilling or insertion of a conduit into the subsurface. A wellbore may have a substantially circular cross section, or other cross-sectional shape. As used herein, the term “well,” when referring to an opening in the formation, may be used interchangeably with the term “wellbore.”
The term “jetting fluid” refers to any fluid pumped through a jetting hose and nozzle assembly for the purpose of erosionally boring a lateral borehole from an existing parent wellbore. The jetting fluid may or may not contain an abrasive material.
The term “abrasive material” or “abrasives” refers to small, solid particles mixed with or suspended in the jetting fluid to enhance erosional penetration of: (1) the pay zone; and/or (2) the cement sheath between the production casing and pay zone; and/or (3) the wall of the production casing at the point of desired casing exit.
The terms “tubular” or “tubular member” refer to any pipe, such as a joint of casing, a portion of a liner, a joint of tubing, a pup joint, or coiled tubing.
The terms “lateral borehole” or “mini-lateral” or “ultra-deep perforation” (“UDP”) refer to the resultant borehole in a subsurface formation, typically upon exiting a production casing and its surrounding cement sheath in a parent wellbore, with said borehole formed in a known or prospective pay zone. For the purposes herein, a UDP is formed as a result of hydraulic jetting forces erosionally boring through the pay zone with a jetting fluid directed through a jetting hose and out a jetting nozzle affixed to the terminal end of the jetting hose. Preferably, each UDP will have a substantially normal trajectory relative to the parent wellbore.
The terms “steerable” or “guidable”, as applied to a hydraulic jetting assembly, refers to a portion of the jetting assembly (typically, the jetting nozzle and/or the portion of jetting hose immediately proximal the nozzle) for which an operator can direct and control its geo-spatial orientation while the jetting assembly is in operation. This ability to direct, and subsequently re-direct the orientation of the jetting assembly during the course of erosional excavation can yield UDP's with directional components in one, two, or three dimensions, as desired.
The terms “perforation cluster” or “UDP cluster” refer to a designed grouping of lateral boreholes off a parent well casing. These groupings are ideally designed to receive and transmit a specific “stage” of a stimulation treatment, usually in the course of completing or recompleting a horizontal well by hydraulic fracturing (or “fracking”).
The term “stage” references a discreet portion of a stimulation treatment applied in completing or recompleting a specific pay zone, or specific portion of a pay zone. In the case of a cased horizontal parent wellbore, up to 10, 20, 50 or more stages may be applied to their respective perforation (or UDP) clusters. Typically, this requires some form of zonal isolation prior to pumping each stage.
The terms “contour” or “contouring” as applied to individual UDP's, or groupings of UDP's in a “cluster”, refers to steerably excavating the UDP (or lateral borehole) so as to optimally receive, direct, and control stimulation fluids, or fluids and proppants, of a given stimulation (typically, fracking) stage. This ability to ‘ . . . optimally receive, direct, and control . . . ’ a given stage's stimulation fluids is designed to retain the resultant stimulation geometry “in zone”, and/or concentrate the stimulation effects where desired. The result is to optimize, and typically maximize, the Stimulated Reservoir Volume (“SRV”).
The terms “real time” or “real time analysis” of geophysical data (such as micro-seismic, tiltmeter, and or ambient micro-seismic data) that is obtained during the course of pumping a stage of a stimulation (such as fracking) treatment means that results of said data analysis can be applied to: (1) altering the remaining portion of the stimulation treatment (yet to be pumped) in its pump rates, treating pressures, fluid rheology, and proppant concentration in order to optimize the benefits therefrom; and, (2) optimizing the placement of perforations, or contouring the trajectories of UDP's, within the subsequent “cluster(s)” to optimize the SRV obtained from the subsequent stimulation stages.
A downhole hydraulic jetting assembly is provided herein. The jetting assembly is designed to direct a jetting nozzle and connected hydraulic hose through a window formed along a string of production casing, and then “jet” one or more boreholes outwardly into a subsurface formation. The lateral boreholes essentially represent ultra-deep perforations that are formed by using hydraulic forces directed through a flexible, high pressure jetting hose, having affixed to its distal end a high pressure jetting nozzle. The subject assembly capitalizes on a single hose and nozzle apparatus to continuously jet, optionally, both a casing exit and the subsequent lateral borehole.
The jetting assembly 50 generally includes an internal system 1500 and an external system 2000. The jetting assembly 50 is designed to be run into a wellbore 4 at the end of a working string, sometimes referred to herein as a “conveyance medium.” Preferably, the working string is a string of coiled tubing 100. The conveyance medium 100 may be conventional coiled tubing. Alternatively, a “bundled” product that incorporates electrically conductive wiring and data conductive cables (such as fiber optic cables) around the coiled tubing core, protected by an erosion/abrasion resistant outer layer(s), such as PFE and/or Kevlar, or even another (outer) string of coiled tubing may be used. It is observed that fiber optic cables have a practically negligible diameter, and are oilfield-proven to be efficient in providing direct, real-time data transmission and communications with downhole tools. Other emerging transmission media such as carbon nanotube fibers may also be employed.
Other conveyance media may be used for the jetting assembly 50. These include, for example, a standard e-coil system, a customized FlatPAK® assembly, PUMPTEK's® Flexible Steel Polymer Tubing (“FSPT”) or Flexible Tubing Cable (“FTC”) tubing. Alternatively, tubing have PTFE (Polytetrafluorethylene) and Kevlar®-based materials, or Draka Cableteq USA, Inc.'s® Tubing Encapsulated Cable (“TEC”) system may be used. In any instance, it is desirable that the conveyance medium 100 be flexible, somewhat malleable, non-conductive, pressure resistant (to withstand high pressure fracturing fluids optionally being pumped down the annulus), temperature resistant (to withstand bottom hole wellbore operating temperatures, often in excess of 200° F., and sometimes exceeding 300° F.), chemical resistant (at least in resistance to the additives included in the frac fluids), friction resistant (to minimize the downhole pressure loss due to friction while pumping the frac treatment), erosion resistant (to withstand the erosive effects of afore-mentioned annular fracturing fluids) and abrasion resistant (to withstand the abrasive effects of proppants suspended in the aforementioned annular fracturing fluids).
If a standard coiled tubing string is employed, communications and data transmission may be accomplished by hydro-pulse technology (or so-called mud-pulse telemetry), acoustic telemetry, EM telemetry, or some other remote transmission/reception system. Similarly, electricity for operating the apparatus may be generated downhole by a conventional mud motor(s), which would allow the electrical circuitry for the system to be confined below the end of the coiled tubing. The present hydraulic jetting assembly 50 is not limited by the data transmission system or the power transmission or the conveyance medium employed unless expressly so stated in the claims.
It is preferred to maintain an outer diameter of the coiled tubing 100 that leaves an annular area within the approximate 4.0″ I.D. of the casing 12 that is greater than or equal to the cross-sectional area open to flow for a 3.5″ O.D. frac (tubing) string. This is because, in the preferred method (after jetting one or more, preferably two opposing mini-laterals, or even specially contoured “clusters” of small-diameter lateral boreholes), fracture stimulation can immediately (after repositioning the tool string slightly uphole) take place down the annulus between the coiled tubing conveyance medium 100 plus the external system 2000, and the well casing 12. For 9.2#, 3.5″ O.D. tubing (i.e., frac string equivalent), the I.D. is 2.992 inches, and the cross-sectional area open to flow is 7.0309 square inches. Back-calculating from this same 7.0309 in2 equivalency yields a maximum O.D. available for both the coiled tubing conveyance medium 100 and the external system 2000 (having generally circular cross-sections) of 2.655″. Of course, a smaller O.D. for either may be used provided such accommodate a jetting hose 1595.
In the view of
The internal system 1500 is designed to be housed within the external system 2000 while being conveyed by the coiled tubing conveyance medium 100 and the attached external system 2000 in to and out of the parent wellbore 4. Extension of the internal system 1500 from and retraction back into the external system 2000 is accomplished by the application of: (a) hydraulic forces; (b) mechanical forces; or (c) a combination of hydraulic and mechanical forces. Beneficial to the design of the internal 1500 and external 2000 systems comprising the hydraulic jetting apparatus 50 is that transport, deployment, or retraction of the jetting hose 1595 never requires the jetting hose to be coiled. Specifically, the jetting hose 1595 is never subjected to a bend radius smaller than the I.D. of production casing 12, and that only incrementally while being advanced along the whipstock 1050 of the jetting hose whipstock member 1000 of the external system 2000. Note the jetting hose 1595 is typically ¼th″ to ⅝ths″ I.D., and up to approximately 1″ O.D., flexible tubing that is capable of withstanding high internal pressures.
The internal system 1500 first includes a battery pack 1510.
The upstream battery pack end cap 1520 has a conductive ring about a portion of its circumference. When the internal system 1500 is “docked” (i.e., matingly received into a docking station 325 of the external system 2000) the battery pack end cap 1520 can receive and transmit current and, thus, re-charge the battery pack 1550. Note also that the end caps 1520 and 1530 can be sized so as to house and protect any servo, microchip, circuitry, geospatial or transmitter/receiver components within them.
The battery pack end-caps 1520, 1530 may be threadedly attached to the battery pack casing 1540. The battery pack end-caps 1520, 1530 may be constructed of a highly erosive- and abrasive-resistant, high pressure material, such as titanium, perhaps even further protected by a thin, highly erosive- or abrasive-resistant coating, such as polycrystalline diamond. The shape and construction of the end-caps 1520, 1530 are preferably such that they can deflect the flow of high pressure jetting fluid without incurring significant wear. The upstream end cap 1520 must deflect flow to an annular space (not shown in
Thus, the path of the high pressure hydraulic jetting fluid (with or without abrasives) is as follows:
Worthy of note in the above-described jetting fluid flow sequence are the following initiation conditions:
Referring back to
The geo-steering system can also be utilized to control the rotational speed of a rotor body within the jetting nozzle 1600. As will be described more fully below, the rotating nozzle configuration utilizes the rotor portion 1620 of a miniature direct drive electric motor assembly to also form a throat and end discharge slot 1640 of the rotating nozzle itself. Rotation is induced via electromagnetic forces of a rotor/stator configuration. In this way, rotational speeds can be governed in direct proportion to the current supplied to the stators.
As depicted in
Referring now to
Note that because the longitudinal axis of the nozzle's discharge stream is designed to be continuous to and aligned with that of the nozzle throat, there is virtually no axial moment acting on the nozzle from thrust of the exiting jetting fluid. That is, as the nozzle is designed to operate in an axially “balanced” condition, the torque moment required to actually rotate the nozzle about its longitudinal axis is relatively small. Similarly, in that relatively low rotational speeds (RPM's) are required for rotational excavation, the electromagnetic force required from the nozzle's rotor/stator interaction is relatively small as well.
Note from
The length of many of the components can also be adjusted. For example, though the battery pack 1510 in
Referring again to the docking station 325, the docking station 325 serves as a physical “stop” beyond which the internal system 1500 can no longer travel upstream. Specifically, the upstream limit of travel of the internal system 1500 (comprised primarily of the jetting hose 1595) is at that point where the upstream battery pack end cap 1520 lodges (or, “docks”) within a bottom, conically-shaped receptacle 328 of the docking station 325. The receptacle 328 serves as a lower end cap. The receptacle 328 provides matingly conductive contacts which line up with the upstream battery pack end cap 1520 to form a docking point. In this way, a transfer of data and/or electrical power (specifically, to recharge batteries 1551) can occur while “docked.”
The docking station 325 also has a conically-shaped end-cap 323 at the upstream (proximal) end of the docking station 325. The conical shape serves to minimizing erosive effects by diverting the flow of jetting fluid around the body thereof, thereby aiding in the protection of the system components housed within the docking station 325. Depending on the guidance, steering, and communications capabilities desired, an upper portion 323 of the docking station 325 can house the servo, transmission, and reception circuitry and electronics systems designed to communicate directly (either in continuous real time, or only discretely while docked) with counterpart systems in the internal system 1500. Note, as shown in
The internal system 1500 next includes a jetting fluid receiving funnel 1570.
In the design of
b provides a second axial, cross-sectional view of the fluid intake funnel 1570. This view is taken across line B-B′ of
Downstream from the jetting fluid receiving funnel 1570 is a jetting hose seal assembly 1580.
Also visible in
As previously described, the upper seal 1580U of the jetting hose's seal assembly 1580 (shown as a solid portion with a slightly concave upwards upper face) precludes any continued downstream flow of jetting fluid outside of the jetting hose 1595. Similarly, the lower seal 1580L of this seal assembly 1580 (shown as a series of concave-downwards cup faces) precludes any upstream flow of hydraulic fluid from below. Note how any upstream-to-downstream hydraulic pressure from the jetting fluid will tend to expand the jetting fluid intake funnel 1570 and, thus, urge the upper seal 1580U of the seal assembly 1580 radially outwards to sealingly engage the I.D. 420.1 of the jetting hose carrier's (inner) jetting hose conduit 420. Similarly, any downstream-to-upstream hydraulic pressure from the hydraulic fluid radially expands bottom cup-like faces making up the lower seal 1580L to sealingly engage the I.D. 420.1 of the jetting hose carrier's inner conduit 420. Thus, when jetting fluid pressure is greater than the trapped hydraulic fluid pressure, the overbalance will tend to “pump” the entire assembly “down-the-hole”. Conversely, when the pressure overbalance is reversed, hydraulic fluid pressure will tend to “pump” the entire seal assembly 1580 and connected hose 1595 back “up-the-hole”.
Returning to
As noted, the downward hydraulic pressure of the jetting fluid acting upon the axial cross-sectional area of the jetting hose's fluid receiving funnel 1570 creates an upstream-to-downstream force that tends to “pump” the seal assembly 1580 and connected jetting hose 1595 “down the hole.” In addition, because the components of the fluid receiving funnel 1570 and the supporting upper seal 1580U of the seal assembly 1580 are slightly flexible, the net pressure drop described above serves to swell and flare the outer diameters of upper seal 1580U radially outwards, thus producing a fluid seal that precludes fluid flow behind the hose 1595.
In the preferred embodiment, the jetting hose 1595 is a “bundled” product. The hose 1595 may be obtained from such manufacturers as Parker Hannifin Corporation. The bundled hose includes at least three electrically conductive wires 1590, and at least one, but preferably two dedicated data cables 1591 (such as fiber optic cables), as depicted in
Moving now down the hose 1595 to the distal end,
As described in the related applications, the jetting hose 1595 immediately preceding this point of casing exit “W” spans the entire I.D. of the production casing 12. In this way, a bend radius “R” of the jetting hose 1595 is provided that is always equal to the I.D. of the production casing 12. This is significant as the subject assembly 50 will always be able to utilize the entire casing (or wellbore) I.D. as the bend radius “R” for the jetting hose 1595, thereby providing for utilization of the maximum I.D./O.D hose. This, in turn, provides for placement of maximum hydraulic horsepower (“HHP”) at the jetting nozzle 1600, which further translates in the capacity to maximize formation jetting results such as penetration rate, or the lateral borehole diameter, or some optimization of the two.
It is observed here that there is a consistency of three “touch points” for the bend radius “R” of the jetting hose 1595. First, there is a touch point where the hose 1595 contacts the I.D. of the casing 12. This occurs at a point directly opposite and slightly (approximately one casing I.D. width) above the point of casing exit “W.” Second, there is a touch point along a whipstock curved face 1050.1 of the whipstock member 1000 itself. Finally, there is a touch point against the I.D. of the casing 12 at the point of casing exit “W,” at least until the window “W” is formed.
As depicted in
As described in greater detail in the co-owned U.S. Pat. No. 8,991,522, the whipstock rod is part of a tool assembly that also includes an orienting mechanism, and an anchoring section that includes slips. Once the slips are set, the orienting mechanism utilizes a ratchet-like action that can rotate the upstream portion of the whipstock member 1000 in discreet 10° increments. Thus, the angular orientation of the whipstock member 1000 within the wellbore may be incrementally changed downhole.
In one embodiment, the whipstock 1050 is a single body having an integral curved face configured to receive the jetting hose and redirect the hose about 90 degrees. Note the whipstock 1050 is configured such that, at the point of casing exit when in set and operating position, it forms a bend radius for the jetting hose that spans the entire ID of the parent wellbore's production casing 12.
a is an axial, cross-sectional view of the whipstock member 1000, with a perspective view of sequential axial jetting hose cross-sections depicting its path downstream from the center of the whipstock member 1000 at line O-O′ to the start of the jetting hose's bend radius as it approaches line P-P′.
b depicts an axial, cross-sectional view of the whipstock member 1000 at line P-P′. Note the adjustments in location and configuration of both the whipstock member's wiring chamber and hydraulic fluid chamber from line O-O′ to line P-P′.
As noted above, the present assembly 50 is preferably used in connection with a nozzle having a unique design.
First,
Residing along each of the shoulders 1615 is a small diameter, electrically conductive wire 1616 wrapping the stator's inwardly facing shoulders (or “stator poles”) 1615 with multiple wraps. Movement of electrical current through the wires 1616 thus creates electro-magnetic forces in accordance with a DC rotor/stator system. Power to the wires is provided from the batteries 1551 (or battery pack 1550) of
As noted above, the stator 1610 and rotor 1620 bodies are analogous to a direct drive motor. The stator 1610 (in this depiction, a six-pole stator) of this direct drive electric motor analog is included within the outer body of the nozzle 1600 itself, with each pole protruding directly from the body 610, and commensurately wrapped in electric wire 1616. The current source for the wire 1616 wrapping the stator poles is derived through the ‘bundled’ electrical wires 1590 of the jetting hose 1595, and is thereby manipulated by the current regulator and micro-servo mechanism housed in the conically-shaped battery pack's (downstream) end-cap 1530. Rotation of the rotor 1620 of the nozzle 1600, and particularly the speed of rotation (RPM's), is controlled via induced electro-magnetic forces of a DC rotor/stator system.
Note that
b provides a longitudinal, cross-sectional view of the nozzle 1600 of
It is observed in
Simulations were conducted with the single planar slot slightly twisted such that the discharge angle(s) of the fluid generated sufficient thrust so as to rotate the nozzle 1600. The observed problem was that nozzle rotation rates were hypersensitive to changes in fluid flow rates, leaving the concern of instantaneous and frequent overloading (with resultant failure) of the bearings 1630. The solution was to design, as nearly as possible, a balanced single slot system, such that there is no appreciable axial thrust generated by fluid discharge. In other words, the nozzle 1600 is no longer sensitive to injection rate.
At this point it is important to note the basic nozzle design criteria for the flow capacity of the combined flow path comprised of the throat 1650 and slot 1640 elements. That is, that these inner throat 1650 and slot 1640 elements of the nozzle 1600 retain dimensions that can approximate the dimensions, and resultant hydraulics, of conventional hydraulic jet casing perforators. Specifically, the nozzle 1600 depicted in
Angles θSLOT 1641 and θMAX 1642 are shown in
a and 3F-2b provide longitudinal, cross-sectional views of the jetting nozzle of
The nozzle configuration of
c is an axial, cross-sectional view of the jetting nozzle 1601 of
Note particularly in a homogeneous host pay zone, the forward (jetting) hydraulic horsepower requirement necessary to excavate fresh rock at a given rate of penetration would be essentially constant. The rearward thrust hydraulic horsepower requirement, however, is constantly increasing in proportion to the growth in length of the mini-lateral. As continued extension of the mini-lateral requires dragging an ever-increasing length of jetting hose 1595 along an ever-increasing distance, the rearward thrusting hydraulic horsepower requirement to maintain forward propulsion of the jetting nozzle 1601 and hose 1595 increases commensurately.
It may be required to consume upwards of two-thirds of available horsepower through the rearward thrust jets 1613 in order to extend the jetting hose 1595 and connected nozzles 1601, 1602 to the furthest lateral extent. If this maximum requirement is utilized constantly throughout the borehole jetting process, much of the available horsepower will be wasted in the early stages in jetting the bore. This is particularly detrimental when the same jetting nozzle and assembly utilized in rock excavation is also utilized to form the initial casing exit “W.” Further, if the same rearwards jetting forces cutting the ‘points’ of the star-shaped rock excavation are active in the wellbore tubulars (particularly, while jetting the casing exit “W”) significant damage to the nearby tool string (particularly, the whipstock member 1000) and the well casing 12 could result. Hence, the optimum design would provide for the activation/deactivation of the rearward thrust jets 1613 when desired, particularly, after the casing exit is formed and after the first 5 or 10 feet of lateral borehole is formed.
There are several possible mechanisms by which jet activation/deactivation may be enabled to help conserve HHP and protect the tool string and tubulars. One approach is mechanical, whereby the opening and closing of flow to the jets 1613 is actuated by overcoming the force of a biasing mechanism. This is shown in connection with the spring 1635 of
The second of the three additions incorporated into the nozzle design of
In
The third of the three additions incorporated into the nozzle 1601 design of
To illustrate, suppose that system hydraulics provide for a suitable pump rate of 0.5 BPM through the nozzle 1601 at the point of casing exit “W,” and that this can be sustained at a surface pumping pressure of 8,000 psi. Suppose further that actuation of the thrust jets 1613 in the nozzle 1601 is not required until the nozzle 1601 achieves a lateral distance of 50 feet from the parent wellbore. That is, particularly while jetting the casing exit “W” itself and an abrasive mixture (say, of 1.0 ppg of 100 mesh sand in a 1 pound guar-based fresh water gel system) is being pumped, none of the jets 1613 have been opened (which could risk clogging by the abrasive in the jetting fluid mixture.) Consequently, no abrasives are included in the jetting fluid after it is sure that the nozzle 1600 has sufficiently cleared the casing exit “W”. Accordingly, while jetting the hole in production casing 12 to form casing exit “W”, no rearwards jetting forces from fluids expelled through thrust jets 1613 can pose a threat to unintentionally damage either the jetting hose 1595, the whipstock member 1000, or the production casing 12.
Later, after generating the casing exit “W” plus a mini-lateral length of, say, approximately 50 feet, the pump pressure is increased to 9,000 psi, the incremental 1,000 psi increase in surface pumping pressure being sufficient to overcome the force of the biasing mechanism 1635 and act against the cross-sectional area of the protrusion of the insert 1631 to actuate the jets 1613. Thus, at mini-lateral length of 50 feet from the parent wellbore 4, the thrust jets 1613 are actuated, and high pressure rearwards thrust flow is generated through the jets 1613.
Suppose these conditions are sufficient to continue jetting a mini-lateral out to a lateral length of 300 feet. At 300 feet, the length of jetting hose laying against the floor of the mini-lateral is causing a commensurate frictional resistance such that it and the thrust forces generated through the thrust jets 1613 are in approximate equilibrium. (Instrumentation such as tensiometers, for example, would indicate this.) At this point, the pump rate is increased to, say, 10,000 psi, and the rearward thrust jets 1613 remain actuated, but at higher differential pressures and flow rates, thus generating higher pull force on the jetting hose 1595.
a and 3F-3c provide longitudinal, cross-sectional views of a jetting nozzle 1602, in yet another alternate embodiment. Here, multiple rearward thrust jets 1613, and a single forward jetting slot 1640, are again used. A collar 1633 and spring 1635 are again used for providing selective fluid flow through rearward thrust jets 1613.
b and 3F-3d provide axial, cross-sectional views of the jetting nozzle 1602 of
The nozzle 1602 of
The nozzle 1602 of
It is also observed that in the nozzle 1602, the number of rearward thrust jets 1613, though also symmetrically placed about the circumference of the rotor 1610, has been increased from a single set of five to two sets of four. Note that each of the four jets 1613 within each of the two sets are also symmetrically placed about the rotor 1610 circumference, orthogonally relative to each other; hence, the two sets of jets 1613 must overlap. Additionally, the path of each jet now not only travels through the rearward (stator) portion 1610 of the nozzle 1602, but now also through the forward (rotor) section 1620 of the nozzle 1602. Note, however, as depicted in
The commensurate subtraction of jetting fluid volumes going through the nozzle port 1640 produces a commensurate pulsating forward jetting flow for excavation, as well. The benefits of pulsating flow over and against continuous flow for excavation systems are well documented, and will not be repeated here. Note, however, the subject nozzle design not only captures the rock excavation benefits of a rotating jet, but also the benefits of a pulsating jet.
Another embodiment of a thrust collar that employs an electromagnetic force is provided in
The collar 1700 has a rear stator 1710 and an inner (rotating) rotor 1720. The stator 1710 defines an annular body having a series of inwardly facing shoulders 1715 equi-distantly spaced therein, while the rotor 1720 defines a body having a series of outwardly facing shoulders 1725 equi-distantly spaced therearound. In the arrangement of
Residing along each of the shoulders 1715 is a small diameter, electrically conductive wire 1716 wrapping the stator's 1710 inwardly facing shoulders (or, “stator poles”) 1715 with multiple wraps. Movement of electrical current through the wires 1716 thus creates electro-magnetic forces in accordance with a DC rotor/stator system. Power to the wires is provided from the batteries 1551 of
b is a longitudinal, cross-sectional view of the nozzle 1700.
a thru 3G-1c show the embodiment of similar concepts for the rotating nozzles 1600, 1601, and 1602, but with modifications adapting the apparatus for use as an in-line thrust jetting collar 1700. Note particularly the retention of a flow-through rotor 1725 providing a collar throat 1750, coupled with a stator 1715 and bearings 1730. However, the stationary flow channels for the rearward thrusting jets 1713 penetrating the stator 1710 are staggered, being in two sets of four. The single set of four orthogonal jets penetrating the rotor 1725 will, for each full rotation, “match-up” four times each with the jets penetrating the stator 1710, each match-up providing a four-pronged instantaneous pulsed flow spaced equi-distant about the outer circumference of the collar 1700. Similar to the rotating nozzle 1602, the slideable collar 1733 is moved electromagnetically against a biasing mechanism (spring) 1735 to actuate flow through the rearward thrust jets 1713.
c is another cross-sectional view, showing the star pattern of the rearward thrust jets 1713. Eight points are seen.
A unique opportunity exists to configure the collar 1733 as either a net power consumer or a net power provider. The former would rely on the battery pack-provided power, just as the jetting nozzle 1600 does, to fire the stator, rotate the rotor, and generate the requisite electromagnetic field. The latter is accomplished by incorporating interior, slightly angled turbine fins 1740 within the I.D. of the rotor 1720, hence harnessing the hydraulic force of the jetting fluid as it is pumped through the collar 1700. Such force would be dependent only on the pump rate and the configuration of the turbine fins 1740.
In one aspect, internal turbine fins 1740 are placed equi-distant about the collar throat 1750, such that hydraulic forces are harnessed both to rotate the rotor 1720 and to supply a net surplus of electrical current to be fed back into the internal system's circuitry. This may be done by sending excess current back up wires 1590. The ability to incorporate a rotor/stator configuration into construction of the rearward thrust jet collar enables a full-opening I.D. equal to that of the jetting hose. More than ample hydroelectric power could be obtained to generate the electromagnetic field needed to operate the slideable port collar 1733, the surplus being available to be fed into the now “closed” electrical system incurred once the internal system 1500 disengages from the docking station 325. Hence, this surplus hydroelectric power generated by the collar 1700 may beneficially be used to maintain charges of the batteries 1551 in the battery pack 1550.
It is observed that the various nozzle designs 1600, 1601, 1602 discussed above are designed to jet not only through a rock matrix, but also through the steel casing and the surrounding cement sheath of the wellbore 4c in order to reach the rock. The nozzle designs incorporate the ability to handle relatively large mesh-size abrasives through the forward nozzle jetting port 1640 prior to engaging the RTJ's 1613. It is understood though that other nozzle designs may be used that accomplish the purpose of forming mini-laterals but which are not so robust as to cut through steel.
In the various nozzle designs 1600, 1601, 1602 discussed above, a single forward port in a hemispherically-shaped nozzle is used. The forward port 1640 is defined by the angles θMAX (whereby the width of the jet is equal to the width of the nozzle when the outermost edge of the jet reaches a point forward equivalent to the nozzle tip) and θSLOT (the actual slot angle). Note θSLOT≦θMAX. For presentation purposes herein, θSLOT=θMAX, such that even if the tip of the rotating nozzle was against the host rock (or casing I.D.) face while jetting, it would still excavate a tunnel diameter equal to the outer (maximum) nozzle diameter. It is this single-plane, rotating slot configuration that will provide a maximum width in order to accommodate ample pass-through capacity for any abrasives that may be incorporated in the jetting fluid.
The preferred rearward orifice jet orientation is from 30° 60° from the longitudinal axis. The rearward thrust jets 1613/1713 are designed to be symmetrical about the circumference of the nozzle's/collar's stator body 1610/1710. This maintains a purely forwards orientation of the jetting nozzle 1600, 1601, 1602 along the longitudinal axis. Accordingly, there should be at least three jets 1613/1713 spaced equi-distant about the circumference, and preferably at least five equi-distant jets 1613/1713.
As noted above, the nozzle in any of its embodiments may be deployed as part of a guidance, or geo-steering, system. In this instance, the nozzle will include at least one geo-spatial IC chip, and will employ at least three actuator wires. The actuator wires 1590A are spaced equi-distant about the distal end of the jetting hose and extend into the nozzle, and receive electrical current, or excitation, from the electrical wires 1590 already provided in the jetting hose 1595.
c is a longitudinal cross-sectional view of the jetting nozzle 1600 of
In the arrangement of
d is an axial-cross-sectional view of the jetting hose 1590 of
The micro-transmitter in the battery pack is preferably housed in the battery pack's downstream end cap 1530, while the docking station 325 is preferably affixed to the interior of a jetting hose carrier system 400 (described below in connection with
The reverse (surface-to-downhole instrumentation) communication is likewise facilitated by hard-wired (again, preferably fiber optic) connection of surface instrumentation, through fiber optic cable 107 within coiled tubing conveyance medium 100 and external system 2000, to a specific terminus receiver (not shown) housed within the docking station 325. An adjoining wireless transmitter within the docking station 325 then transmits the operator's desired commands to a wireless receiver housed within the end cap 1530 of the internal system 1500. This communication system allows an operator to execute commands setting both the rotational speed and/or the trajectory of the jetting nozzle 1600.
When the nozzle 1600 exits the casing, the operator knows the location and orientation of the nozzle 1600. By monitoring the length of jetting hose 1590 that is translated out of the jetting hose carrier, integrated with any changes in orientation, the operator knows the geo-location of the nozzle 1600 in the reservoir.
In one option, a desired geo-trajectory is first sent as geo-steering command from the surface 1, down the coiled tubing 100, and to the micro-processor associated with the docking station 325. Upon receiving a geo-steering command from the surface 1, such as from an operator or a surface control system, the micro-processor will forward the signals on wirelessly to a corresponding micro-receiver associated with the battery pack section 1550. That signal will engage one or more current regulators to alter the current conducted down one, two, or all three of the at least three electric wires 1590, connected directly to the jetting nozzle 1600. Note that at least part of these electrical wire connections, preferably segments closest to the jetting nozzle 1600, are comprised of actuator wires 1590A, such as the Flexinol® actuator wires manufactured by Dynalloy, Inc. These small diameter, nickel-titanium wires contract when electrically excited. This ability to flex or shorten is characteristic of certain alloys that dynamically change their internal structure at certain temperatures. The contraction of actuator wires is opposite to ordinary thermal expansion, is larger by a hundredfold, and exerts tremendous force for its small size. Given close temperature control under a constant stress, one can get precise position control, i.e., control in microns or less. Accordingly, given (at least) three separate actuator wires 1590A positioned at-or-near equidistant around the perimeter and within the body of the jetting hose (toward its end, adjacent to the jetting nozzle 1600), a small increase in current in any given wire will cause it to contract more than the other two, thereby steering the jetting nozzle 1600 along a desired trajectory. Given an initial depth and azimuth via the geo-spatial IC chip in the nozzle 1600, a determined path for a lateral borehole 15 may be pre-programmed and executed automatically.
Of interest, the actuator wires 1590A have a distal segment residing along a chamber or sheath, or even interwoven within the matrix of the distal segment of the jetting hose 1595. Further, the distal end of the actuator wires 1590A may continue partially into the nozzle body, wrapping the stator poles 1615 to connect to, or even form the electro-magnetic coils 1616. This is also demonstrated in
As can be seen from the above discussion, an internal system 1500 for a hose jetting assembly 50 is provided. The system 1500 enables a powerful hydraulic nozzle (1600, 1601, 1602) to jet away subsurface rock in a controlled (or steerable) manner, thereby forming a mini-lateral borehole that may extend many feet out into a formation. The unique combination of the internal system's 1500 jetting fluid receiving funnel 1570, the upper seal 1580U, the jetting hose 1595, in connection with the external system's 2000 pressure regulator valve 610 and pack-off section 600 (discussed below) provide for a system by which advancement and retraction of the jetting hose 1595, regardless of the orientation of the wellbore 4, can be accomplished entirely by hydraulic means. Alternatively, mechanical means may be added through use of an internal tractor system 700, described more fully below.
Not only can the above-listed components be controlled to determine the direction of the jetting hose 1595 propulsion (e.g., either advancement or retraction), but also the rate of propulsion. The rate of advancement or retraction of the internal system 1500 may be directly proportional to the rate of fluid (and pressure) bleed-off and/or pump-in, respectively. Specifically, “pumping the hose 1595 down-the-hole” would have the following sequence:
Similarly, the internal system 1500 can be pumped back “up-the-hole” by directing the pumping of hydraulic fluid through (first) the main control valve 310 and (secondly) through the pressure regulator valve 610, thereby forcing an ever-increasing (expanding) volume of hydraulic fluid into the micro-annulus 1595.420 between the jetting hose 1595 and the jetting hose conduit 420, which pushes upwardly against the bottom seals 1580L of the jetting hose seal assembly 1580, thereby driving the internal system 1500 back “up-the-hole”. The direction and rate of propulsion of the internal system 1500 by hydraulic means can be either augmented or replaced by propulsion of the internal system 1500 via the mechanical means of the internal tractor system 700, also described below.
Beneficially, once the jetting hose assembly 50 is deployed to a downhole location adjacent a desired point of casing exit “W” within a parent wellbore 4 of any inclination (including at-or-near horizontal), the entire length of jetting hose 1595 can be deployed and retrieved without any assistance from gravitational forces. This is because the propulsion forces used to both deploy and retrieve the jetting hose 1595, and to maintain its proper alignment while doing so, are either hydraulic or mechanical, as described more fully, below. Note also these propelling hydraulic and mechanical forces are available in more than sufficient quantities as to overcome any frictional forces from movement of the internal system 1500 (including, specifically, the jetting hose 1595) within the external system 2000 (including, specifically, the jetting hose conduit 420) induced by any non-vertical alignment, and to maintain the hose 1595 in a substantially taught state along the hose length within the external system 2000. Hence, these hydraulic and mechanical propulsion forces overcome the “can't-push-a-rope” limitation in its entirety.
Hydraulic force to advance the jetting hose 1595 within and subsequently out of the external system 2000 will be observed any time jetting fluid is being pumped; specifically, force in a plane parallel to the longitudinal axis of the jetting hose 1595, in an upstream-to-downstream direction, as hydraulic force is exerted against the upstream end-cap of the battery pack 1520, the fluid intake funnel 1570, the interior face of the jetting nozzle 1600, e.g., any internal system 1500 surface that is both: (a) exposed to the flow of jetting fluid; and, (b) having a directional component not parallel to the longitudinal axis of the parent wellbore. As these surfaces are rigidly attached to the jetting hose 1595 itself, this upstream-to-downstream force is conveyed directly to the jetting hose 1595 whenever jetting fluid is being pumped from the surface 1, down the coiled tubing conveyance medium 100 (seen in
Conversely, hydraulic forces are operational in propelling the internal system 1500 in a downstream-to-upstream direction whenever hydraulic fluid is being pumped from the surface 1, down the coiled tubing conveyance medium 100, and through the hydraulic fluid passage 340 within the main control valve 300. In this configuration, the pressure regulator valve 610 allows the operator to direct injected fluids into the jetting hose 1595/jetting hose conduit 420 annulus 1595.420 commensurate with the operator's desired rate of ascent of the internal system 1500. Thus, hydraulic forces are available to assist in both conveyance and retrieval of the jetting hose 1595.
Similarly, mechanical forces applied by the internal tractor system 700 assist in conveyance, retrieval, and maintaining alignment of the jetting hose 1595. The close tolerance between the O.D. of the jetting hose 1595 and the I.D. of the jetting hose conduit 420 of jetting hose carrier system 400, thus defining annulus 1595.420, serves to provide confining axial forces that assist in maintaining the alignment of the hose 1595, such that the portion of the hose 1595 within the jetting hose carrier system 400 can never experience significant buckling forces. Direct mechanical (tensile) force for both deployment and retrieval of the jetting hose 1595 is applied by direct frictional attachment of grippers 756 of specially-designed gripper assemblies 750 of the internal tractor system 700 to the jetting hose 1595, discussed below in connection with
As described above, jetting hose conveyance is also assisted by the hydraulic forces emanating from the rearward thrusting jets 1613 of the jetting nozzle 1601, 1602 itself; and, if included, from the rearward thrust jets 1713 of any added jetting collar(s) 1700. These furthest downstream hydraulic forces serve to advance the jetting hose 1595 forward into the pay zone 3 simultaneously with the creation of the UDP 15 (
For presentation purposes, two configurations of rearward thrust jets 1613/1713 have been included herein—one for pulsating flow wherein eight rearward thrust jets, each inclined at 30° from the longitudinal axis and spaced equi-distant about the circumference, are grouped into two sets of four, with rearwards flow alternating (or ‘pulsing’) between the two sets; and one for continuous flow, wherein a single set of five jets, each inclined at 30° from the longitudinal axis and spaced equi-distant about the circumference, are shown. However, other jet numbers and angles may be employed.
The
As noted, the hydraulic jetting assembly 50 also provides an external system 2000, uniquely designed to convey, deploy, and retrieve the internal system 1500 previously described. The external system 2000 is conveyable on conventional coiled tubing 100; but, more preferably, is deployed on a “bundled” coiled tubing product (
Consistent with the related and co-owned patent documents cited herein, the external system 2000 includes a jetting hose whipstock member 1000 including a whipstock 1050 having a curved face 1050.1 that preferably forms the bend radius for the jetting hose 1595 across the entire I.D. of the production casing 12. The external system 2000 may also include a conventional tool assembly comprised of mud motor(s) 1300, (external) coiled tubing tractor(s) 1350, logging tools 1400 and/or a packer or a bridge plug (preferably, retrievable) that facilitate well completion. In addition, the external system 2000 provides for power and data transmission throughout, so that real time control may be provided over the downhole assembly 50.
In presenting the components of the external system 2000, it is assumed that the system 2000 is run into production casing 12 having a standard 4.50″ O.D. and approximate 4.0″ I.D. In one embodiment, the external system 2000 has a maximum outer diameter constraint of 2.655″ and a preferred maximum outer diameter of 2.500″. This O.D. constraint provides for an annular (i.e., between the system 2000 O.D. and the surrounding production casing 12 I.D.) area open to flow equal to or greater than 7.0309 in2, which is the equivalent of a 9.2#, 3.5″ frac (tubing) string.
The external system 2000 is configured to allow the operator to optionally “frac” down the annulus between the coiled tubing conveyance medium 100 (with attached apparatus) and the surrounding production casing 12. Preserving a substantive annular region between the O.D. of the external system 2000 and the I.D. of the production casing 12 allows the operator to pump a fracturing (or other treatment) fluid down the subject annulus immediately after jetting the desired number of lateral bores and without having to trip the coiled tubing 100 with attached apparatus 2000 out of the parent wellbore 4. Thus, multiple stimulation treatments may be performed with only one trip of the assembly 50 in to and out of the parent wellbore 4. Of course, the operator may choose to trip out of the wellbore for each frac job, in which case the operator would utilize standard (mechanical) bridge plugs, frac plugs and/or sliding sleeves. However, this would impose a much greater time requirement (with commensurate expense), as well as much greater wear and fatigue of the coiled tubing-based conveyance medium 100.
In actuality, rigorous adherence to the (O.D.) constraint is perhaps only essential for the coiled tubing conveyance medium 100, which may comprise over 90% of the length of the system 50. Slight violations of the O.D. constraint over the comparatively minute lengths of the other components of the external system 2000 should not impose significant annular hydraulic pressure drops as to be prohibitive. If these outer diameter constraints can be satisfied, while maintaining sufficient inner diameters so as to accommodate the design functionality of each of the components (particularly of the external system 2000), and this can be accomplished for a system 50 that operates in the smaller of standard oilfield production casing 4 sizes of 4.5″ O.D., then there should be no significant barriers to adapting the system 50 to any of the larger standard oilfield production casing sizes (5.5″, 7.0″, etc.).
Presentation of each of the major components of the external system 2000, which follows below, will be in an upstream-to-downstream direction. Note in
a is an axial, cross-sectional view of the coiled tubing conveyance medium 100 of
The coiled tubing conveyance medium 100 also has an outermost, or “wrap,” layer 110. In one aspect, the outer layer 110 has an outer diameter of 2.500″, and an inner diameter bonded to and exactly equal to that of the O.D. 105.2 of the core coiled tubing string 105 of 2.000″.
Both the axial and longitudinal cross-sections presented in
The conveyance medium 101 may have, for example, an internal flow area of 2.0612 in2, a core wall thickness 105 of 0.190 in2, and an average outer wall thickness of 0.25 in2. The outer wall 110 may have a minimum thickness of 0.10 in2.
Note the main design criteria of the conveyance medium, whether concentrically 100 or eccentrically 101 bundled, is to provide real-time power (via electrical wiring 106) and data (via data cabling 107) transmission capacities to an operator located at the surface 1 while deploying, operating, and retrieving apparatus 50 in the wellbore 4. For example, in a standard e-coil system, components 106 and 107 would be run within the coiled tubing core 105, thereby exposing them to any fluids being pumped via the I.D. 105.1 of the core 105. Given the subject method provides for pumping abrasives within a high-pressure jetting fluid (particularly, while eroding casing exit “W” from within production casing 12), it is preferred instead to locate components 106 and 107 at the O.D. 105.2 of the core 105.
Similarly, the subject method provides for pumping proppants within high pressure hydraulic fracturing fluids down the annulus between the coiled tubing conveyance medium 100 (or 101) and production casing 12. Hence, the protective coiled tubing wrap layer 110 is preferably of sufficient thickness, strength, and erosive resistance to isolate and protect components 106 and 107 during fracturing operations.
The present conveyance medium 100 (or 101) also maintains a sufficiently large inner diameter 105.1 of the core wall 105 such as to avoid appreciable friction losses (as compared to the losses incurred in the internal system 1500 and external system 2000) while pumping jetting and/or hydraulic fluids. At the same time, the system maintains a sufficiently small outer diameter 110.2 so as to avoid prohibitively large pressure losses while pumping hydraulic fracturing fluids down the annulus between the coiled tubing conveyance medium 100 (or 101) and the production casing 12. Further, the system 50 maintains a sufficient wall thickness for the outer wrap layer 110, whether it is concentrically or eccentrically wrapped about the inner coiled tubing core 105, so as to provide adequate insular protection and spacing for the electrical transmission wiring 106 and the data transmission cabling 107. It is understood that other dimensions and other tubular bodies may be used as the conveyance medium for the external system 2000.
Moving further down the external system 2000,
The main functions of this crossover connection 200 are as follows:
The next component in the external system 2000 is a main control valve 300.
The function of the main control valve 300 is to receive high pressure fluids pumped from within the coiled tubing 100, and to selectively direct them either to the internal system 1500 or to the external system 2000. The operator sends control signals to the main control valve 300 by means of the wires 106 and/or data cable ports 107.
The main control valve 300 includes two fluid passages. These comprise a hydraulic fluid passage 340 and a jetting fluid passage 345. Visible in
The main control valve 300 also includes a cover pivot 350. The passage cover 320 rotates with rotation of the passage cover pivot 350. The cover pivot 350 is driven by a passage cover pivot motor 360. The sealing passage cover 320 is positioned by the passage cover pivot 350 (as driven by the passage cover pivot motor 360) to either: (1) seal the hydraulic fluid passage 340, thereby directing all of the fluid flow from the coiled tubing 100 into the jetting fluid passage 345, or (2) seal the jetting fluid passage 345, thereby directing all of the fluid flow from the coiled tubing 100 into the hydraulic fluid passage 340.
The main control valve 300 also includes a wiring conduit 310. The wiring conduit 310 carries the electrical wires 106 and data cables 107. The wiring conduit 310 is optionally elliptically shaped at the point of receipt (from the coiled tubing transition connection 200, and gradually transforms to a bent rectangular shape at the point of discharging the wires 106 and cables 107 into the jetting hose carrier system 400. Beneficially, this bent rectangular shape serves to cradle the jetting hose conduit 420 throughout the length of the jetting hose carrier system 400.
The next component of the external system 2000 is a jetting hose carrier system 400.
a is an axial, cross-sectional view of the jetting hose carrier system 400 of
The jetting hose carrier system 400 defines a pair of tubular bodies. The first tubular body is a jetting hose conduit 420. The jetting hose conduit 420 houses, protects, and stabilizes the internal system 1500 and, particularly, the jetting hose 1595. As previously presented in the discussion of the internal system 1500, it is the size (specifically, the I.D.), strength, and rigidity of this fluid-tight and pressure-sealing conduit 420 that provides the pathway and particularly, the micro-annulus (shown at 1595.420 in
The jetting hose carrier section 400 also has an outer conduit 490. The outer conduit 490 resides along and circumscribes the inner conduit 420. In one aspect, the outer conduit 490 and the jetting hose conduit 420 are simply concentric strings of 2.500″ O.D. and 1.500″ O.D. HSt100 coiled tubing, respectively. The inner conduit, or jetting hose conduit 420, is sealed to and contiguous with the jetting fluid passage 345 of the main control valve 300. When high pressure jetting fluid is directed by the valve 300 into the jetting fluid passage 345, the fluid flows directly and only into the jetting hose conduit 420 and then into the jetting hose 1595.
An annular area 440 exists between the inner (jetting hose) conduit 420 and the surrounding outer conduit 490). The annular area 440 is also fluid tight, directly sealed to and contiguous with the hydraulic fluid passage 340 of the control valve 300. When high pressure hydraulic fluid is directed by the main control valve 300 into the hydraulic fluid passage 340, the fluid flows directly into the conduit-carrier annulus 440.
The jetting hose carrier section 400 also includes a wiring chamber 430. The wiring chamber 430 has an axial cross-section of an upwardly-bent rectangular shape, and receives the electrical wires 106 and data cables 107 from the main control valve's 300 wiring conduit 310. This fluid-tight chamber 430 not only separates, insulates, houses, and protects the electrical wires 106 and data cables 107 throughout the entire length of the jetting hose carrier section 400, but its cradle shape serves to support and stabilize the jetting hose conduit 420. Note the jetting hose carrier section 400 wiring chamber 430 and inner (jetting hose) conduit 420 may or may not be attached either to each other, and/or to the outer conduit 490.
In addition to housing and protecting wires 106 and data transmission cables 107, the wiring conduit 430 within the jetting hose carrier system 400 supports the jetting hose conduit's 420 horizontal axis at a position slightly above a horizontal axis that would bifurcate the outer conduit 490. Different types of materials may be utilized in its construction, given its design constraints are significantly less stringent than those for the outer layer(s) of the CT-based conveyance medium, particularly in regard to chemical and abrasion resistance, as the exterior of the wiring conduit 430 will only be exposed to hydraulic fluid—never jetting or fracturing fluids.
Additional design criteria for the wiring conduit 430 may be invoked if it is desired for it to be rigidly attached to either the jetting hose conduit 420, the outer conduit 490, or both. In one aspect, the wiring conduit 430 has a width of approximately 1.34″, and provides three 0.20″ diameter circular channels for electrical wiring, and two 0.10″ diameter circular channels for data transmission cables. It is understood that other diameters and configurations for the wiring conduit 430 may vary, depending on design objectives, so long as an annular area 440 open to flow of hydraulic fluid is preserved.
Also visible in
The length of the jetting hose conduit 420 is quite long, and should be approximately equivalent to the desired length of jetting hose 1595, and thereby defines the maximum reach of the jetting nozzle 1600 orthogonal to the wellbore 4, and the corresponding length of the mini-lateral 15. The inner diameter specification defines the size of the micro-annulus 1595.420 between the jetting hose 1595 and the surrounding jetting hose conduit 420. The I.D. should be close enough to the O.D. of the jetting hose 1595 so as to preclude the jetting hose 1595 from ever becoming buckled or kinked, yet it must be large enough to provide sufficient annular area for a robust set of seals 1580L by which hydraulic fluid can be pumped into the sealed micro-annulus 1595.420 to assist in controlling the rate of deployment of the jetting hose 1595, or assisting in hose retrieval.
It is the hydraulic forces within the sealed micro-annulus 1595.420 that keep the segment of jetting hose (above the internal tractor system 700) straight, and slightly in tension. The I.D. of jetting hose conduit 420 can likewise not be too close to the O.D. of the jetting hose 1595 so as to place unnecessarily high frictional forces between the two. The O.D. of the jetting hose conduit 420 (in conjunction with the I.D. of the outer conduit 490, less the external dimensions of the jetting hose carrier's wiring chamber 430) define the annular area 440 through which hydraulic fluid is pumped. Certainly, if the jetting hose carrier system's inner conduit 420 O.D. is too large, it thereby invokes undue frictional losses in pumping hydraulic fluid. However, if not large enough, then the inner conduit 420 will not have sufficient wall thickness to support either the inner or outer operating pressures required. Note, for the subject apparatus designed to be deployed in 4.5″ wellbore casing, the inner string is comprised of 1.5″ O.D. and 1.25″ I.D. (i.e., 0.125″ wall thickness) coiled tubing. If this were 1.84#/ft., HSt110, for example, it would provide for an Internal Minimum Yield Pressure rating of 16,700 psi. Similarly, the outer conduit 490 can be constructed of standard coiled tubing. In one aspect, the outer conduit 490 is comprised of 2.50″ O.D. and 2.10″ I.D., thereby providing for a wall thickness of 0.20″.
Progressing again uphole-to-downhole, the external system 2000 next includes the second crossover connection 500, transitioning to the jetting hose pack-off section 600.
As its name implies, the main function of the jetting hose pack-off section 600 is to “pack-off”, or seal, an annular space between the jetting hose 1595 and a surrounding inner conduit 620. The jetting hose pack-off section 600 is a stationary component of the external system 2000. Through transition 500, and partially through pack-off section 600, there is a direct extension of the micro-annulus 1595.420. This extension terminates at the pressure/fluid seal of the jetting hose 1595 against the inner faces of seal cups making up the pack-off seal assembly 650. Immediately prior to this terminus point is the location of the pressure regulator valve, shown schematically as component 610 in
The crossover connection 500 from the jetting hose carrier system 400 to the pack off section 600 is notable for several reasons:
First, within this transition 500, the free flow of hydraulic fluid from the conduit-carrier annulus 440 of the jetting hose carrier section 400 will be re-directed and re-compartmentalized within the upper (triangular-shaped) quadrant of the star-shaped outer conduit 690. Toward the upstream end of the inner conduit 620 is the pressure regulator valve 610. The pressure regulator valve 610 provides for increasing or decreasing the hydraulic fluid (and commensurately, the hydraulic pressure) in the micro-annulus 1595.420 between the jetting hose 1595 and the surrounding jetting hose conduit 420. It is the operation of this valve 610 that provides for the internal system 1500 (and specifically, the jetting hose 1595) to be “pumped down,” and then reversibly “pumped up” the longitudinal axis of the production casing 12.
The upwardly bent, rectangular-shaped fluid-tight chamber 430 that separates, insulates, houses, and protects the electrical wires 106 and data cables 107 along the length of the jetting hose carrier body 400 is transitioned via wiring chamber 530 into a lower (triangular-shaped) quadrant 630 of the star-shaped outer body 690 of the pack-off section 600. This preserves the separation, insulation, housing, and protection of the electrical wires 106 and the data cables 107 in the jetting hose pack-off section 600. The star-shaped outer body 690 forms an annulus between itself and the I.D. of the surrounding production casing 12.
Given the prong-tip-to-opposite-prong-tip distances of the four-pronged star-shaped outer conduit 690 are just slightly less than the I.D. of the production casing 12, the pack-off section 600 also serves to nearly centralize the jetting hose 1595 in the parent wellbores production casing 12. As will be explained later, this near-centralization will translate through the internal tractor system 700 so as to beneficially centralize the upstream end of the whipstock member 1000.
Recall the outer diameter of the upstream end of the jetting hose 1595 is hydraulically sealed against the inner diameter of the inner conduit 420 of the jetting hose carrier system 400 by virtue of the jetting hose's upper 1580U and lower 1580L seals, forming a single seal assembly 1580. The seals 1580U and 1580L, being formably affixed to the jetting hose 1595, travel up and down the inner conduit 420. Similarly, the outer diameter of the downstream end of the jetting hose 1595 is hydraulically sealed against the inner diameter of the pack-off section's 600 inner conduit 620 by virtue of the seal assembly 650 of the pack-off section 600. Thus, when the internal system 1500 is “docked” (i.e., when the upstream battery pack end cap 1520 is in contact with the external system's docking station 325) then the distance between the two seal assemblies 1580, 620 approximates the full length of the jetting hose 1595. Conversely, when the jetting hose 1595 and jetting nozzle 1600 have been fully extended into the maximum length lateral borehole (or UDP) 15 attainable by the jetting assembly 50, then the distance between the two seal assemblies 1580, 620 is negligible. This is because, though the internal system's jetting hose seal assembly 1580 essentially travels the entire length of the external system's 2000 jetting hose carrier system 400, the seal assembly 650 (of the pack-off section 600 in the external system 2000) is relatively stationary, as the seal cups comprising seal assembly 650 must reside between opposing seal cup stops 615.
Note further how the alignment of the two opposing sets of seal cups comprising seal assembly 650 (e.g., an upstream set facing upstream, placed back-to-back with a downstream set facing downstream) thereby provides a pressure/fluid seal against differential pressure from either the upstream direction or the downstream direction. These opposing sets of seal cups comprising seal assembly 650 are shown with a longitudinal cross section of jetting hose 1595 running concentrically through them, in the enlarged view of
As noted, the pressure maintained in the micro-annulus 1595.420 by the pressure regulator valve 610 provides for the hydraulic actions of “pumping the hose down the hole” or, reversibly, “pumping the hose up the hole”. These annular hydraulic forces also serve to mitigate other, potentially harmful forces that could be imposed on the jetting hose 1595, such as buckling forces when advancing the hose 1595 downstream, or internal burst forces while jetting. Hence, combined with the upper hose seal assembly 1580 and the jetting hose conduit 420, the jetting hose pack-off section 600 serves to maintain the jetting hose 1595 in an essentially taut condition. Hence, the diameter of the hose 1595 that can be utilized will be limited only by the bend radius constraint imposed by the I.D. of the wellbore's production casing 12, and the commensurate pressure ratings of the hose 1595. At the same time, the length of the hose 1595 that may be utilized is certainly well into the hundreds of feet.
Note the most likely limiting constraint of hose 1595 length will not be anything imposed by the external system 2000, but instead will be the hydraulic horsepower distributable to the rearward thrust jets 1613/1713, such that sufficient horsepower can remain forward-focused for excavating rock. As one might expect, the length (and commensurate volume) of mini-laterals that can be jetted will ultimately be a function of rock strength in the subsurface formation. This length limitation is quite unlike the system posited in U.S. Pat. No. 6,915,853 (Bakke, et al.) that attempts to convey the entirety of the jetting hose downhole in a coiled state within the apparatus itself. That is, in Bakke, et al., the hose is stored and transported while in horizontally stacked, 360° coils contained within the interior of the device. In this case, the bend radius/pressure hose limitations are imposed by (among other constraints), not the I.D. of the casing, but by the I.D. of the device itself. This results in a much smaller hose I.D./O.D., and hence, geometrically less horsepower deliverable to Bakke's jetting nozzle.
In operation, after a UDP 15 has been formed and the main control valve 300 has been shifted to shut-off the flow of hydraulic jetting fluid to the internal system 1500 and is then providing flow of hydraulic fluid to the external system 2000, the pressure regulator valve 610 can feed flow into the micro-annulus 1595.420 in the opposite direction. This downstream-to-upstream force will “pump” the assembly back into the wellbore 4 and “up the hole,” as the bottom, downwards facing cups 1580L of the seal assembly 1580 will trap flow (and pressure) below them.
The next component within the external system 2000 (again, progressing uphole-to-downhole) is an optional internal tractor system 700.
It is first observed that two types of tractor systems are known. These are the wheeled tractor systems and the so-called inch-worm tractor systems. Both of these tractor systems are “external” systems, meaning that they have grippers designed to engage the inner wall of the surrounding casing (or, if in an open hole, to engage the borehole wall). Tractor systems are used in the oil and gas industry primarily to advance either a wireline or a string of coiled tubing (and connected downhole tools) along a horizontal (or highly deviated) wellbore—either uphole or downhole.
In the present assembly 50, a unique tractor system has been developed which employs “internal,” grippers. This means that gripper assemblies 750 are aimed inwardly, for the purpose of either advancing or retracting the jetting hose 1595 relative to the external system 2000. The result of this inversion is that the coiled tubing string 100 and attached external system 2000 can now be stationary while the somewhat flexible hose 1595 is being translated in the wellbore 4c. The outwardly-aimed electrically driven wheels of a conventional (“external”) tractor are replaced with inwardly-aimed concave grippers 756. The result is the inwardly-aimed concave grippers 756 frictionally attach to the jetting hose 1595, with subsequent rotation of the grippers 756 propelling the jetting hose 1595 in a direction that corresponds with the direction of rotation.
Note specifically the following consequence of this inversion: In a conventional system, the relative movement that occurs is that of the rigidly gripper-attached body (i.e., the coiled tubing) relative to the stationary, frictionally attached body (i.e., the borehole wall). Conversely, the subject internal tractor system is rigidly attached to the stationary body (i.e., the external system 2000) and the grippers 756 rotate to move the jetting hose 1595. Accordingly, when the internal tractor system 700 is actuated, the whipstock member 1000 will already be in its set and operating position; e.g., the slips of the whipstock member 1000 will be engaged with the inner wall of the casing 12. Hence, all advancement/retraction of the jetting hose 1595 by the tractor system 700 takes place when the external system 2000 itself is set and is stationary within the production casing 12.
It is next observed that the internal tractor system 700 preferably maintains the star-shape profile of the jetting hose pack-off system 600. The star shape profile of the internal tractor system 700, with its four points, helps centralizes the tractor system 700 within the production casing 12. This is beneficial inasmuch as the slips of the whipstock member 1000 (located relatively close to tractor system 700, due to the short lengths of the third crossover connection (or transition) 800 and upper swivel 900 between them, discussed below) will be engaged when operating the tractor system 700, meaning that centralization of the tractor system 700 serves to align the defined path of the jetting hose 1595 and precludes any undo torque at the connection with the jetting hose whipstock device 1000. It is observed in
In addition to centralizing the hose 1595, another function served by the star-shape profile of the tractor system 700 is that it accommodates interior room for placement of two opposing sets of gripper assemblies 750. Specifically, the gripper assemblies 750 reside inside the ‘dry’ working room of the two side chambers, while simultaneously providing for separate chambers for the electrical wires 106 and data cabling 107 (shown in lower chamber 730) and the hydraulic fluid (in upper chamber 740). At the same time, ample cross-sectional flow area is preserved between the tractor system 700 and the I.D. of the production casing 12 within their respective annular area 700.12 for conducting fracturing fluids.
As shown within the 4.5″ production casing 12, the annular area 700.12 open to flow is approximately 10.74 in2, equating to an equivalent pipe diameter (I.D.) of 3.69 in. Recall the design objective is to maintain an annular flow area greater than or equal to the interior area of a typical 3.5″ O.D. (2.922″ I.D., 10.2#/ft.) frac string, i.e. 6.706 in2. Note then, if the tip-to-tip dimension of opposing prongs of the “star” is, for example, 3.95 in, and (to gain additional internal volume within the four chambers of the tractor system 700) the star shape were changed to a perfect square, then the external area of the square would be 7.801 in2, and the remaining annular area (open to flow of frac fluid) inside the 4.00″ I.D. production casing would be 4.765 in2, which is equivalent to a 2.463″ pipe I.D. Hence, though the base of each triangular chamber within the star shape could be somewhat expanded to provide additional internal volumes or wall thickness, the outer perimeter cannot be completely squared-off and still satisfy the preferred 3.5″ frac string criteria. Note, however, there is no reason the triangular dimensions of each chamber must remain symmetrical; e.g., the dimensions could be varied individually in order to accommodate each chamber's internal volume requirements, just as long as the 3.5″ frac string requirement is still preferably satisfied.
Each of the gripper assemblies 750 is comprised of a miniature electric motor 754, and a motor mount 755 securing the motor 754 to the outer wall 790. In addition, each of the gripper assemblies 750 includes a pair of axles. These represent a gripper axle 751 and a gripper motor axle 753. Finally, each of the gripper assemblies 750 includes gripper gears 752.
The tractor system 700 also includes bearing systems 760. The bearing systems 760 are placed along the length of inner walls 720. These bearing systems 760 isolate frictional forces against the jetting hose 1595 at the contact points of the grippers 756, and eliminate unwanted frictional drag against the inner walls 720.
Rearward rotation of the grippers 756 serve to advance the hose 1595, while forward rotation of the grippers 756 serves to retract the hose 1595. Propulsion forces provided by the grippers 756 help advance the jetting hose 1595 by pulling it through the jetting hose carrier system 400, transition 500, and pack-off section 600, and assist in advancing the jetting hose 1595 by pushing it into the lateral borehole 15 itself.
The view of
Optionally, the internal tractor system 700 also includes a tensiometer. The tensiometer is used to provide real-time measurement of the pulling tension of the upstream section of hose 1595 and the pushing compression on the downstream section of hose 1595. Similarly, mechanisms could be included to individualize the applied compressional force of each set of grippers 756 upon the jetting hose 1595, so as to compensate for uneven wear of the grippers 756.
Again proceeding in presentation of the external system's 2000 main components from upstream-to-downstream,
The transition 800 functions similarly to previous transitional sections (200, 500) of the external system 2000 discussed herein. Suffice it to say the main function of the transition 800 is to convert the axial profile of the star-shaped internal tractor system 700 back to a concentric circular profile as used for the swivel 900, and to do so within I.D. restrictions that meet the 3.5″ frac string test.
The upper swivel 900 simultaneously accomplishes three important functions:
Desirable for the simultaneous satisfaction of the above design criteria are the double sets of bearings 960 (the inner bearings) and 965 (the outer bearings). In one aspect, the upper swivel 900 has an O.D. of 2.6 in.
The outer wall 990 of the upper swivel 900 maintains the circular profile achieved by an outer wall 890 of transition 800. Similarly, concentric circular profiles are obtained in the upper swivel's 900 middle body 950 and inner wall 920. These three sequentially and concentrically smaller cylindrical bodies (990, 950, and 920) provide for placement of an inner set of circumferential bearings 960 (between the inner wall 920 and the middle body 950) and an outer set of circumferential bearings 965 (between the middle body 950 and the outer wall 990). The larger cross-sectional area of the middle body 950 allows it to host a horseshoe-shaped hydraulic fluid chamber 940, and an arc-shaped wiring chamber 930. The bearings 960, 965 facilitate relative rotation of the three sequentially and concentrically smaller cylindrical bodies 990, 950, and 920. The bearings 960, 965 also provide for rotatable translation of the whipstock member 1000 below the upper swivel 900 (also shown in FIG. 4G-1) while in its set and operating position. This, in turn, provides for a change in orientation of subsequent lateral boreholes jetted from a given setting depth in the parent wellbore 4. Stated another way, the upper swivel 900 allows an indexing mechanism (described in the related U.S. Pat. No. 8,991,522 and incorporated herein in its entirety) to rotate the whipstock member 1000 without torqueing any upstream components of the external system 2000.
It is also observed that the upper swivel 900 provides for rotation of the whipstock member 1000 while yet maintaining a straight path for the electrical wiring 106 and data cabling 107. The upper swivel 900 also permits the horseshoe-shaped hydraulic fluid chamber 940 to provide for rotation of the whipstock member 1000 while yet maintaining a contiguous hydraulic flow path down to the whipstock member 1000 and beyond.
Returning to
A nozzle 1600 is also shown in
As discussed in U.S. Pat. No. 8,991,522, the jetting hose whipstock member 1000 is set utilizing hydraulically controlled manipulations. In one aspect, hydraulic pulse technology is used for hydraulic control. Release of the slips is achieved by pulling tension on the tool. These manipulations were designed into the whipstock member 1000 to accommodate the general limitations of the conveyance medium (conventional coiled tubing) 100, which can only convey forces hydraulically (e.g., by manipulating surface and hence, downhole hydraulic pressure) and mechanically (i.e., tensile force by pulling on the coiled tubing, or compressive force by utilizing the coiled tubing's own set-down weight).
The jetting hose whipstock member 1000 is herein designed to accommodate the delivery of wires 106 and data cables 107 further downhole. To this end, a wiring chamber 1030 (conducting electrical wires 106 and data cables 107) is provided. Power and data are provided from the external system 2000 to conventional logging equipment 1400, such as a Gamma Ray—Casing Collar Locator logging tool, in conjunction with a gyroscopic tool. This would be attached immediately below a conventional mud motor 1300 and coiled tubing tractor 1350. Hence, for this embodiment, hydraulic conductance through the whipstock 1000 is desirable to operate a conventional (“external”) hydraulic-over-electric coiled tubing tractor 1350 immediately below, and electrical (and preferably, fiber optic) conductance to operate the logging sonde 1400 below the coiled tubing tractor 1350. The wiring chamber 1030 is shown in the cross-sectional views of
Note that this tractor 1350 is placed below the point of operation of the jetting nozzle 1600, and therefore will never need to conduct either the jetting hose 1595 or high pressure jetting fluids to generate either the casing exit “W” or subsequent lateral borehole. Hence, there are no I.D. constraints for this (bottom) coiled tubing tractor 1350 other than the wellbore itself. The coiled tubing tractor 1350 may be either of the conventional wheel (“external roller”) type, or the gripper (inch worm) type.
A hydraulic fluid chamber 1040 is also provided along the jetting hose whipstock member 1000. The wiring chamber 1030 and the fluid chamber 1040 become bifurcated while transitioning from semi-circular profiles (approximately matching their respective counterparts 930 and 940 of the upper swivel 900) to a profile whereby each chamber occupies separate end sections of a rounded rectangle (straddling the whipstock member 1050). Once sufficiently downstream of the whipstock member 1050, the chambers can be recombined into their original circular pattern, in preparation to mirror their respective dimensions and alignments in a lower swivel 1100. This enables the transport of power, data, and high pressure hydraulic fluid through the whipstock member 1000 (via their respective wiring chamber 1030 and hydraulic fluid chamber 1040) down to the mud motor 1300.
Below the whipstock member 1000 and the nozzle 1600 but above the tractor 1350 is an optional lower swivel 1100.
The lower swivel 1100 is essentially a mirror-image of the upper swivel 900. As with the upper swivel 900, the lower swivel 1100 includes an inner wall 1120, a middle body 1150, and an outer wall 1190. In a preferred embodiment, the outer conduit has an O.D. of 2.60″, or slightly less. The constraint of the O.D. outer conduit 1190 is the self-imposed 3.5″ frac string equivalency test.
The middle body 1150 further houses wiring chamber 1130 and a hydraulic fluid chamber 1140. The fluid chamber 1140 transports hydraulic fluid to crossover connection 1200 and eventually to the mud motor 1300.
The lower swivel 1100 also includes a wiring chamber 1130 that houses electrical wires 106 and data cables 107. Continuous electrical and/or fiber optic conductance may be desired when real time conveyance of logging data (gamma ray and casing collar locator, “CCL” data, for example) or orientation data (gyroscopic data, for example) is desired. Additionally, continuous electrical and/or fiber optic conductance capacity enables direct downhole assembly manipulation from the surface 1 in response to the real time data received.
It is noted that while the inner conduit 920 of the upper swivel 900 defines a hollow core of sufficient dimensions to receive and conduct the jetting hose 1595, the lower swivel 1100 has no such requirement. This is because in the design of the assembly 50 and the methods of usage thereof, the jetting hose 1595 is never intended to proceed downstream to a point beyond the whipstock member 1050. Accordingly, the innermost diameter of the lower swivel 1100 may in fact be comprised of a solid core, as depicted in
The lower swivel 1100 resides between the jetting hose whipstock member 1000 and any necessary crossover connections 1200 and downhole tools, such as a mud motor 1300 and the coiled tubing tractor 1350. Logging tools 1400, a packer, or a bridge plug (preferably retrievable, not shown) may also be provided. Note that, depending on the length of the horizontal portion 4c of the wellbore 4, the respective sizes of the conveyance medium 100 and production casing 12, and hence the frictional forces to be encountered, more than one mud motor 1300 and/or CT tractor 1350 may be needed.
The final figure presented is
It is anticipated that, in preparation for a subsequent hydraulic fracturing treatment in a horizontal parent wellbore 4c, an initial borehole 15 will be jetted substantially perpendicular to and at or near the same horizontal plane as the parent wellbore 4c, and a second lateral borehole will be jetted at an azimuth of 180° rotation from the first (again, perpendicular to and at or near the same horizontal plane as the parent wellbore). In thicker formations, however, and particularly given the ability to steer the jetting nozzle 1600 in a desired direction, more complex lateral bores may be desired. Similarly, multiple lateral boreholes (from multiple setting points typically close together) may be desired within a given “perforation cluster” that is designed to receive a single hydraulic fracturing treatment stage. The complexity of design for each of the lateral boreholes will typically be a reflection of the hydraulic fracturing characteristics of the host reservoir rock for the pay zone 3. For example, an operator may design individually contoured lateral boreholes within a given “cluster” to help retain a hydraulic fracture treatment predominantly “in zone.”
It can be seen that an improved downhole hydraulic jetting assembly 50 is provided herein. The assembly 50 includes an internal system 1500 comprised of a guidable jetting hose and rotating jetting nozzle that can jet both a casing exit and a subsequent lateral borehole in a single step. The assembly 50 further includes an external system 2000 containing, among other components, a carrier apparatus that can house, transport, deploy, and retract the internal system to repeatably construct the requisite lateral boreholes during a single trip into and out of a parent wellbore 4, and regardless of its inclination. The external system 2000 provides for annular frac treatments (that is, pumping fracturing fluids down the annulus between the coiled tubing deployment string and the production casing 12) to treat newly jetted lateral boreholes. When combined with stage isolation provided by a packer and/or spotting temporary or retrievable plugs, thus providing for repetitive sequences of plug-and-UDP-and-frac, completion of the entire horizontal section 4c can be accomplished in a single trip.
In one aspect, the assembly 50 is able to utilize the full I.D. of the production casing 12 in forming the bend radius 1599 of the jetting hose 1595, thereby allowing the operator to use a jetting hose 1595 having a maximum diameter. This, in turn, allows the operator to pump jetting fluid at higher pump rates, thereby generating higher hydraulic horsepower at the jetting nozzle 1600 at a given pump pressure. This will provide for substantially more power output at the jetting nozzle, which will enable:
Also of significance, the internal system 1500 allows the jetting hose 1595 and connected jetting nozzle 1600 to be propelled independently of a mechanical downhole conveyance medium. The jetting hose 1595 is not attached to a rigid working string that “pushes” the hose and connected nozzle 1600, but instead uses a hydraulic system that allows the hose and nozzle to travel longitudinally (in both upstream and downstream directions) within the external system 2000. It is this transformation that enables the subject system 1500 to overcome the “can't-push-a-rope” limitation inherent to all other hydraulic jetting systems to date. Further, because the subject system does not rely on gravitational force for either propulsion or alignment of the jetting hose/nozzle, system deployment and hydraulic jetting can occur at any angle and at any point within the host parent wellbore 4 to which the assembly 50 can be “tractored” in.
The downhole hydraulic jetting assembly allows for the formation of multiple mini-laterals, or bore holes, of an extended length and controlled direction, from a single parent wellbore. Each mini-lateral may extend from 10 to 500 feet, or greater, from the parent wellbore. As applied to horizontal wellbore completions in preparation for subsequent hydraulic fracturing (“frac”) treatments in certain geologic formations, these small lateral wellbores may yield significant benefits to optimization and enhancement of fracture (or fracture network) geometry and subsequent hydrocarbon production rates and reserves recovery. By enabling: (1) better extension of the propped fracture length; (2) better confinement of the fracture height within the pay zone; (3) better placement of proppant within the pay zone; and (4) further extension of a fracture network prior to cross-stage breakthrough, the lateral boreholes may yield significant reductions of the requisite fracturing fluids, fluid additives, proppants, hydraulic horsepower, and hence related fracturing costs previously required to obtain a desired fracture geometry, if it was even attainable at all. Further, for a fixed input of fracturing fluids, additives, proppants, and horsepower, preparation of the pay zone with lateral boreholes prior to fracturing could yield significantly greater Stimulated Reservoir Volume, to the degree that well spacing within a given field may be increased. Stated another way, fewer wells may be needed in a given field, providing a significance of cost savings. Further, in conventional reservoirs, the drainage enhancement obtained from the lateral boreholes themselves may be sufficient as to preclude the need for subsequent hydraulic fracturing altogether.
As an additional benefit, the downhole hydraulic jetting assembly 50 and the methods herein permit the operator to apply radial hydraulic jetting technology without “killing” the parent wellbore. In addition, the operator may jet radial lateral boreholes from a horizontal parent wellbore as part of a new well completion. Still further, the jetting hose may take advantage of the entire I.D. of the production casing. Further yet, the reservoir engineer or field operator may analyze geo-mechanical properties of a subject reservoir, and then design a fracture network emanating from a customized configuration of directionally-drilled lateral boreholes.
The hydraulic jetting of lateral boreholes may be conducted to enhance fracture and acidization operations during completion. As noted, in a fracturing operation, fluid is injected into the formation at pressures sufficient to separate or part the rock matrix. In contrast, in an acidization treatment, an acid solution is pumped at bottom-hole pressures less than the pressure required to break down, or fracture, a given pay zone. (In an acid frac, however, pump pressure intentionally exceeds formation parting pressure.) Examples where the pre-stimulation jetting of lateral boreholes may be beneficial include:
The downhole hydraulic jetting assembly 50 and the methods herein permit the operator to conduct acid fracturing operations through a network of lateral boreholes formed through the use of a very long jetting hose and connected nozzle that is advanced through the rock matrix. In one aspect, the operator may determine a direction of a pressure sink in the reservoir, such as from an adjacent producer. The operator may then form one or more lateral boreholes in an orthogonal direction, and then conduct acid fracturing through that borehole. In this instance, fractures will open in the direction of the pressure sink.
The operator may alternatively consider or determine a flux-rate of acid (or other formation-dissolving fluid) in the rock matrix. In this instance, the acid is not injected at a formation parting pressure, but allows wormholes to form in the direction of the pressure sink. The operator may also conduct the steps of creating a pressure boundary in the reservoir by injecting fluids into a first lateral borehole in a first direction, and then performing acid-fracturing through a second lateral borehole in a second direction offset from the first direction. The acid fractures are in the form of wormholes in a direction that does not intersect the pressure boundary.
The downhole hydraulic jetting assembly 50 and the methods herein also permit the operator to pre-determine a path for the jetting of lateral boreholes. Such boreholes may be controlled in terms of length, direction or even shape. For example, a curved borehole or each “cluster” of curved boreholes may be intentionally formed to further increase SRV exposure of the formation 3 to the wellbore 4c. Wellbores may optionally be formed in corkscrew patterns to further expose the formation 3 to the wellbore 4c.
The downhole hydraulic jetting assembly 50 and the methods herein also permit the operator to re-enter an existing wellbore that has been completed in an unconventional formation, and “re-frac” the wellbore by forming one or more lateral boreholes using hydraulic jetting technology. The hydraulic jetting process would use the hydraulic jetting assembly 50 of the present invention in any of its embodiments. There will be no need for a workover rig, a ball dropper/ball catcher, drillable seats or sliding sleeve assemblies.
The downhole hydraulic jetting assembly 50 and the methods herein also permit the operator to create a network of lateral boreholes that includes side mini-lateral boreholes formed off of newly-created boreholes. Such a method may include the steps of:
The method may further comprise:
The method may further comprise (h) repeating steps (a) through (g) at least once to form a network of side mini-lateral boreholes, the network being configured to optimize a Stimulated Reservoir Volume (SRV) (i) from a subsequent hydraulic fracturing treatment, (ii) from a subsequent acid treatment, or (iii) both. Alternatively, the method may further comprise:
The method may then include producing hydrocarbon fluids from the network of side mini-lateral boreholes.
Based on the downhole hydraulic jetting assembly 50 described above, a unique method of forming a wellbore may be conducted. The method, in one embodiment, includes:
In this method, advancing the jetting hose into each of the lateral boreholes is done at least in part through a hydraulic force acting on a sealing assembly along (such as at an upstream end of) the jetting hose. Further, the jetting hose is advanced and subsequently withdrawn without coiling or uncoiling the jetting hose in the wellbore.
In one embodiment, advancing the jetting hose into each of the lateral boreholes is further done through a mechanical force applied by rotating grippers of a mechanical tractor assembly located within the wellbore, wherein the grippers frictionally engage an outer surface of the jetting hose.
In another embodiment, advancing the jetting hose into each of the lateral boreholes is accomplished by forward thrust forces generated from flowing jetting fluid through rearward thrust jets located in the jetting assembly. These rearward thrust jets are specifically located in the jetting nozzle, or in a combination of the nozzle and one or more in-line jetting collars strategically located along the jetting hose. Preferably, the nozzle permits a flow of the jetting fluid through rearward thrust jets in response to a designated hydraulic pressure level. In this instance, the flowing of fluid through the rearward thrust jets is only activated after the jetting hose has advanced into each borehole at least 5 feet from the parent wellbore. The additional rearward thrust jets located in the in-line jetting collar(s) are then activated at incrementally higher operating pressures, typically when the jetting hose has been extended such a significant length from the parent wellbore that the rearward thrust jets within the nozzle alone can no longer generate significant pull force to continue dragging the full length of jetting hose along the lateral borehole.
In a related aspect, the method may include monitoring tensiometer readings at a surface. The tensiometer readings are indicative of drag experienced by the jetting hose as lateral boreholes are formed. In this instance, the flowing of fluid through the rearward thrust jets is activated in each of the plurality of boreholes in response to a designated tensiometer reading.
This application claims the benefit of U.S. Provisional Patent Appl. No. 62/198,575 filed Jul. 29, 2015. That application is entitled “Downhole Hydraulic Jetting Assembly, and Method for Forming Mini-Lateral Boreholes.” This application also claims the benefit of U.S. Provisional Patent Appl. No. 62/120,212 filed Feb. 24, 2015 of the same title. This application is also filed as a continuation-in-part of U.S. patent application Ser. No. 14/612,538 filed Feb. 3, 2015. That application is entitled “Method of Testing a Subsurface Formation for the Presence of Hydrocarbon Fluids.” That application, in turn, is a Divisional of U.S. Pat. No. 8,991,522 issued Mar. 31, 2015. These applications are all incorporated by reference herein.
| Number | Date | Country | |
|---|---|---|---|
| 62198575 | Jul 2015 | US | |
| 62120212 | Feb 2015 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 13198802 | Aug 2011 | US |
| Child | 14612538 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 14612538 | Feb 2015 | US |
| Child | 15009623 | US |
