Patent Grant
11939825
When drilling oil and gas wells using conventional methods, loss circulation events may result when the formation being drilled is highly fractured or otherwise contains large fractures. Expensive drilling mud or other drilling fluid that would otherwise flow up the annulus between the drill string and the wall of the wellbore to carry away cuttings and other materials is lost into the formation if the fractured formation is not addressed. Moreover, in normal drilling operations it is important to keep hydrostatic pressure on the annular side within a particular range for the drilled zone to prevent any influxes or hole collapse or, in more severe instances, kicks and even blowouts. Loss circulation due to large fractures in the formation may result in insufficient annular side hydrostatic pressure and may result in the aforementioned undesirable consequences.
One conventional approach to dealing with a loss circulation events is to stop pumping of drilling mud, and then pumping a specialized loss circulation material down the hole to block the fractures and thus prevent drilling mud from disappearing into the fractured formation. This procedure is time-consuming and expensive. When significant fractures or fracture zones are encountered, the typical loss circulation materials that are currently used are not effective.
Another approach to the problem of loss circulation events involves suspending drilling operations, removing the drill string from the wellbore, and running and cementing casing across the fractured zone of the formation. This procedure is also time-consuming and expensive.
In addition, when significant loss circulation events occur, it is typically necessary to refill the wellbore annulus around the drill string with an amount of drilling mud that was lost during the event. When the well location is remote, it may be difficult to maintain a sufficient supply of drilling mud on hand to account for such events, leading to additional costs and delay in drilling operations.
Accordingly, there exists a need for an improved tool, system, and method for dealing with loss circulation events resulting from drilling through highly fractured formations.
This summary is provided to introduce a selection of concepts that are further described below in the detailed description. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter.
In one aspect, embodiments disclosed herein relate to injector tools for injecting a special, rapidly solidifying sealant, precisely into the fractured formation voids, during drilling activities. Such a tool may be included in a standard drilling BHA in a passive mode and activated when required.
In another aspect of this disclosure, embodiments illustrated and described herein relate to methods of transporting the sealant down the hole in an inactive mode and activating the sealant when exiting a dedicated tool at depth, across the fractured formation, squeezing the sealant into the voids in formation.
In yet another aspect, embodiments disclosed herein relate to systems including injector tools, rapidly solidifying sealants suitable for filling and blocking or sealing voids in highly fractured formations through which a wellbore passes, and containers for storing and deploying the sealant at depth into the formations.
In another aspect, embodiments disclosed herein relate to systems having a single container for delivering a rapidly solidifying sealant that is activated by heat, pressure, or other conditions in the formation, or environmental conditions created by other components of such systems.
In another aspect, embodiments disclosed herein relate to systems having a multiple containers for delivering separate components of a material that, upon mixing of the separate components, becomes an activated rapidly solidifying sealant that may be injected or flowed into the fractured formation.
In another aspect, embodiments disclosed herein relate to systems for delivering rapidly solidifying sealant into a fractured formation via frangible darts pumped down the drill pipe to an injector tool.
Other aspects and advantages of the claimed subject matter will be apparent from the following description and the appended claims.
Specific embodiments of the disclosed technology will now be described in detail with reference to the accompanying figures. Like elements in the various figures are denoted by like reference numerals for consistency.
In the following detailed description of embodiments of the disclosure, numerous specific details are set forth in order to provide a more thorough understanding of the disclosure. However, it will be apparent to one of ordinary skill in the art that the disclosure may be practiced without these specific details. In other instances, well-known features have not been described in detail to avoid unnecessarily complicating the description.
Throughout the application, ordinal numbers (e.g., first, second, third, etc.) may be used as an adjective for an element (i.e., any noun in the application). The use of ordinal numbers is not to imply or create any particular ordering of the elements nor to limit any element to being only a single element unless expressly disclosed, such as using the terms “before”, “after”, “single”, and other such terminology. Rather, the use of ordinal numbers is to distinguish between the elements. By way of an example, a first element is distinct from a second element, and the first element may encompass more than one element and succeed (or precede) the second element in an ordering of elements.
In one aspect, embodiments disclosed herein relate to apparatus, devices, tools, and methods for addressing and remedying loss circulation events during conventional drilling of subterranean and subsea oil, gas, and other types of wells. In conventional drilling, a bottomhole assembly (“BHA”) typically comprising a drill bit (which is itself may be part of a drill bit sub), a mud motor, stabilizers, drill collar, jarring devices (“jars”), drill pipe, and crossovers for various threadforms is lowered into a surface hole to drill a wellbore or borehole. The BHA may also optionally include directional drilling and measuring equipment, measurements-while-drilling tools, logging-while-drilling tools, and other specialized devices.
As the BHA is advanced, drilling mud or other fluid is typically pumped down the drill string and out of the BHA through ports in the bit and/or bit sub. As rock cuttings and other material are created and displaced by the bit from the formation being drilled, the drilling mud entrains such cuttings and materials and floats and carries them up the borehole through an annulus formed between the drill string and the wall of the borehole, and eventually out of the wellbore for separation, treatment, and reuse of the drilling mud.
Typically, the circulating drilling mud provides a number of operational benefits during drilling, in addition to carrying away the rock cuttings created by the rotating bit. The weight of the column of mud in the borehole annulus provides hydrostatic pressure that helps maintain the integrity of the wall of the borehole until casing operations are commenced. The circulating mud also provides lubrication and cooling of the rotating drill string and all of the components of the drill string during drilling.
A problem arises when a drill bit enters or passes through a zone or region of a formation having significant fractures. The formation may be any geological formation from which drilling fluid such as oil or gas may be produced by drilling a wellbore and extracting the fluid from the formation. A wellbore may be any drilled hole used to extract hydrocarbons, gas, or water from the formation. Fractures are separations or cracks in geological formations that divide one or more rocks. Fractures may be microfractures, natural fractures, or hydraulic fractures.
More specifically, when significant fractured zones are encountered during drilling activities, the typical result is loss of expensive drilling mud into the formation and increased non-productive time spent address this problem. This is referred to as circulation loss, or a circulation loss event or occurrence. If not addressed and resolved, circulation loss may cause hydrostatic pressure in the wellbore annulus to drop, resulting in loss of the primary well barrier. In some occasions, the circulation loss event can result in a kick and even a blowout.
In some instances of circulation loss, pumping of drilling mud downhole is suspended and specialized loss circulation fluids are pumped down the drill string, out the BHA, and into the fractured zone of the formation in an effort to block the fractures and prevent further loss of drilling mud into the formation. However, when significant fractures are encountered, typical loss circulation fluids currently in use are not always effective.
In the situation illustrated in
A system including an injection tool 1 such as in the following described embodiments may be incorporated into or included in a conventional drilling BHA. The injection tool 1 may be run downhole in a passive mode and activated when required in the event of detection of a loss circulation event or occurrence. Multiple different recipes, formulations, and materials may be used as the sealant, as long as the chosen material or combination of materials exhibits the property of rapid solidification in the anticipated downhole environment having known temperature, pressure, and other physical characteristics. Suitable sealants include cements, multi-part epoxy compounds, heat-activated single- or multi-part resin compounds, and the like as are known to persons having ordinary skill in the drilling arts.
The injector tool 1 of the embodiment shown in
In the embodiment of
In the embodiment of
The port cover dart 6 may be moved from its inactive position shown in
In the embodiment of
The injection tool 1 of the embodiment shown in
As illustrated in the embodiment of
As described hereinabove, the configuration of the system and its component parts, and its proper alignment across a fractured formation, is critical for preventing the sealant from solidifying around the tool and “cementing the tool in the hole.” To this end, typically a small amount of sealant will be displaced on each attempt to cure the loss of drilling mud into the fractured formation. Displacement of small amounts of sealant also help to prevent cementing the tool in the hole.
Nonetheless, more than one container may be pumped down to the injector tool 1 when larger volume displacement of sealant is required, or when multiple sealing operations are necessary at different depths during drilling operations. In other embodiments (not shown), the injector tool 1 may allow for a coil or umbilical to be run from the surface and latched into the injector tool 1, instead of pumping down separate containers of sealant, to allow pumping higher volumes of sealant from the surface directly into the formation. This embodiment and method can be beneficial when attempting to fill larger caves and openings with rapidly solidifying sealant. Such techniques are especially suited for use with single-component sealants or, in the case of multi-part sealants, with a dart that precisely engages the injector tool in the required position so as to deliver two different components of a sealant into the separate channels 4a,4b of the injection port 4.
In another embodiment illustrated schematically in
The injection tool 901 may be one part of a BHA and in some embodiments may include externally protruding stabilizer pads as previously mentioned.
As seen in the embodiment of
Referring to
In one embodiment of use of the system illustrated in
As seen in the embodiment of
In an embodiment shown in
Typically, a rapidly solidifying sealant will be used. Such sealant is required to expand, solidify, and harden when exiting the displacement slot 5 in such way that sealant will get injected into the fractured formation 17 and in such hardened condition 19 will block the voids under a high differential pressure acting on the sealant and pushing it through the voids during solidification, as seen in
In one embodiment, sealant can be pre-installed into an annular chamber of the injector tool 1 or in a form of the container 3 that has a annular configuration with a through-bore. In some embodiments, the injector tool 1 or the container 3 will have an activation feature to allow a pressure build-up to squeeze the sealant out of the tool 1 or container 3 and thereby pump it through the injection ports 4. Typically, in such embodiments either the injector tool 1 or the container 3 might consist of a ball-catching seat for releasably receiving the well operator to pump a ball from the surface down the drill pipe to reach the dedicated ball-catching seat and generate pressure build-up when and where required. Once operations of pumping sealant are completed, such ball would then be released to unblock the internal bore of the injector tool 1 and allowing drilling fluid to be pumped again to the drill bit.
In one embodiment as illustrated in
In some embodiments, typical cement for cement casing in the well may be even used. In some embodiments, large volumes of sealant, including cement, can be pumped from the surface to displace across the larger fractures. As previously disclosed in connection with the embodiment of
As illustrated in the embodiment of
In an embodiment (not shown), the container 3 may have a single annular sealant chamber therein for transporting one fluid or material, such as a meltable sealant or, alternatively, a cement material prepared at the surface and packaged into the container at the surface. Time delay solidifying or temperature controlled solidifying cements and the like are suitable. In the illustrated embodiment, the container 3 is provided with multiple separate annular chambers 21,21′,22 arranged in end-to-end fashion, in which chambers 21 and 21′ contain two parts of a multi-part expanding, rapidly solidifying sealant, and optional chambers 22 (one at each end, above and below chambers 21 and 21′) may contain a third material, such as a port cleaning fluid or solvent or other material as desired. When optional chambers 22 are included and contain a port cleaning fluid or the like, the cleaning fluid will be displaced from the injection tool 1 through the channels 4a,4b of the injection port 4 thus preventing the fluid passages from themselves becoming sealed, and thus allowing reuse of the injection tool for subsequent injection of additional sealant, if necessary or desired.
As shown in the embodiment of
In a disclosed embodiment, the sealant parts 2,2′ may be squeezed out of their respective chambers by increasing the pressure inside the drill string and thus inside the bore the injector tool 1. High pressure fluid will flow into high pressure chamber 15 located at each end of the pistons 14 through fluid connection ports 16 and will thereby act on the pistons 14 to drive them and the fluids inside the chambers towards the injection ports 4. In some embodiments, the container 3 might include one or multiple rupture disks 13 that will rupture and open generally at the same time in response to high pressure exerted by the fluids 2,2′ inside the chambers 21,21′ when pressure inside the tool has been sufficiently increased above the rupture threshold of the disks 13.
With reference to the flowchart of
The injector tool 1 may be pre-installed in the BHA replacing one or more of the standard string stabilizer tools otherwise employed (Block 802). Where three stabilizers would be installed in the BHA, one of them may be replaced with the injector tool 1 in such way that standard drilling operations will not be affected. Other combinations of downhole tools, and substitution of other BHA tools, or merely the addition of the injector tool 1 at any suitable position in the BHA, is contemplated.
In some embodiments, the injector tool 1 may be included in an alternative BHA assembly designed specifically for use in deal with loss circulation events, similar to a hole cleaning assembly used for a well-cleaning run. In this situation, however, use of the injector tool would first require withdrawal of the drill string from the wellbore, and is thus not preferred.
The injection ports 4 of the injector tool 1 are initially closed and all drilling fluids are circulated from surface to the bit. No fluids exit through the injection ports 4 during normal drilling operations. In some embodiments, the injection port cover dart 6 may be used to close and open the injection ports 4 when required.
Typically, when a significant loss circulation event occurs, the depth of the fractured formation 17 is recorded. The injector tool 1 may be precisely positioned across the fractured formation 17 in such way that the injection ports 4 and the displacement slots 5 are positioned directly across the fractures in the formation. In other embodiments, depending on buoyancy of the particular sealant to be used downhole drilling mud in place, the injector tool 1 could be positioned above or below the fractured formation when starting the sealant displacement into the fractured formation 17.
After positioning the injection tool 1 at the appropriate location (Block 804), a container 3 with a multi-part sealant 2,2′ may be inserted into the drill string at the surface, and pumped down inside the drill string to the container seat face 7 inside the injector tool 1 (Block 806). Alternatively, in one or more embodiments, the injection tool 1 may be pre-installed with the sealant rather than sent from the surface in a container. When the container 3 reaches the container seat face 7 inside the injector tool 1, the operator at the surface observes a confirmation event which, in some embodiments, may be a pressure increase within the drill string, thus confirming the correct landing of the container 3 inside the injection tool 1 (Block 808). In some embodiments, other confirmation methods typically used in oil and gas drilling tools can be used such as: pressure fluctuation, down hole telemetry (mud pulse, acoustic telemetry, etc.), and other known techniques.
Next, the injection port of the injector tool is opened (Block 810). In some embodiments, the container 3 pushes the injection port cover dart 6 out of its initial position. In such embodiments, the injection port cover dart 6 will disengage the container seat face 7 and travel into the container catcher sub 9 located below the injector tool 1. In other embodiments, other methods for opening the injection ports 4 may be employed.
In any case, once the container 3 lands on the container seat face 7, the injection ports 4 will typically open. At this point in operation of the devices and system of one of the disclosed embodiments, the configuration will be as is shown in
During injecting of the sealant into the fractured formation 17, the injection tool 1 may be slowly rotated with entire drill string. Such slow rotation may be at rotational speeds of 5-30 RPM in some embodiments. In some situations, the pressure differential across the wellbore and fractured formation will help to draw the sealant into the fractures 17 and solidify 19 within (Block 814).
In the condition of the container 3 illustrated in
Once the mixed sealant components exit the injector tool 1, they will be squeezed towards the fractures 17 and/or flow towards the fractures and solidify rapidly 19 therein. It may occur in some embodiments that only some of the sealant will enter the fractured formation solidify therein, thus sealing the fractures. The remaining sealant that can no longer flow into the fractured formation may solidify inside the wellbore, but is be sufficiently displaced from the drill string by the stabilizer pads so as to allow for the continued upward flow of drilling mud when normal drilling operations are resumed. In addition, hardened sealant in this situation will typically be crushed between the BHA and the wellbore and will flow back to surface with cuttings during normal drilling circulation.
In some embodiments, once all of the sealant has been squeezed out of the container 3, the cleaning fluids will next be squeezed out through the same path to clean the injection ports 4 and displacement slots 5 (Block 816), as previously disclosed.
When a container 3 has been emptied, it could be disengaged from the container seat face and moved below the injection tool 1 into the container catcher 9 sub. In some embodiments, an empty container 3 may be removed and replaced with a second, similar container and an additional application of sealant may be initiated (Block 818). This may be repeated multiple times as necessary for each fracture to be sealed.
After the fractured formation has been successfully plugged, in one embodiment, the last-emptied container may be removed by use of another injection port cover dart 6 that will close the injection ports 4 and restore the fully sealed internal diameter of the central bore of the injection tool 1.
In some embodiments, the container 3 may be manufactured from a dissolvable material, such as magnesium, and dissolve after emptying it down the hole or once moved inside the container catcher sub 9. In other embodiments, the empty container or containers may be fished out with a conventional wireline fishing tool deployed inside the drill string.
After removing the container or containers from the BHA, in the case of non-dissolvable or non-frangible containers, then normal drilling operations may be resumed.
Embodiments of the present disclosure may provide at least one of the following advantages. The rapidly solidifying sealant is required to harden/expand/solidify when exiting the displacement slot in such way that sealant is injected into the fractured formation and block the voids under a high differential pressure acting on the sealant and pushing it through the voids during solidification. When fractured zones are encountered during drilling operations, significant losses of drilling mud and other drilling fluids may be reduced or prevented. Interruptions and suspensions of normal drilling operations may be eliminated or reduced, and non-productive time may thus be minimized. Further, loss circulation events may be remedied without any requirement of running and cementing casing across the fractured zone. Finally, drilling through highly fractured zones may be simplified.
Although only a few example embodiments have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the example embodiments without materially departing from this invention. Accordingly, all such modifications are intended to be included within the scope of this disclosure as defined in the following claims. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents, but also equivalent structures. Thus, although a nail and a screw may not be structural equivalents in that a nail employs a cylindrical surface to secure wooden parts together, whereas a screw employs a helical surface, in the environment of fastening wooden parts, a nail and a screw may be equivalent structures. It is the express intention of the applicant not to invoke 35 U.S.C. § 112(f) for any limitations of any of the claims herein, except for those in which the claim expressly uses the words ‘means for’ together with an associated function.
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| 20230193706 A1 | Jun 2023 | US |
