1. Field of the Disclosure
Embodiments disclosed herein relate generally to downhole tools. In particular, embodiments disclosed herein relate to expandable underreamers and related methods of use.
2. Background Art
In the drilling of oil and gas wells, typically concentric casing strings are installed and cemented in the wellbore as drilling progresses to increasing depths. Each new casing string is supported within the previously installed casing string, thereby limiting the annular area available for the cementing operation. Further, as successively smaller diameter casing strings are suspended, the flow area for the production of oil and gas is reduced. Therefore, to increase the annular space for the cementing operation, and to increase the production flow area, it is often desirable to enlarge the wellbore below the terminal end of the previously cased wellbore. By enlarging the wellbore, a larger annular area is provided for subsequently installing and cementing a larger casing string than would have been possible otherwise. Accordingly, by enlarging the wellbore below the previously cased wellbore, the bottom of the formation can be reached with comparatively larger diameter casing, thereby providing more flow area for the production of oil and gas.
Various methods have been devised for passing a drilling assembly through a cased wellbore, or in conjunction with expandable casing to enlarge the wellbore. One such method involves the use of an underreamer, which has basically two operative states—a closed or collapsed state, where the diameter of the tool is sufficiently small to allow the tool to pass through the existing cased wellbore, and an open or partly expanded state, where one or more arms with cutters on the ends thereof extend from the body of the tool. In this latter position, the underreamer enlarges the wellbore diameter as the tool is rotated and lowered in the wellbore.
Because the underreamer may be positioned a distance uphole from a drill bit on a distal end of the drillstring, an un-reamed portion of the wellbore, often referred to in the industry as the rat hole, may exist between the underreamer and the drill bit after the borehole is enlarged. In certain instances, the distance may be up to 125 feet or more. To underream the rat hole, the first underreamer is often removed from the wellbore and replaced with a second underreamer, requiring multiple trips into the wellbore.
Accordingly, there exists a need for an integrated reamer system capable of fully underreaming a wellbore and providing measurement data of the enlarged wellbore.
In one aspect, embodiments disclosed herein relate to a downhole reaming system including a tubular body having a drill bit disposed on a distal end thereof, and a central bore therethrough, wherein the tubular body is attached to a drillstring, an expandable reamer having cutter blocks coupled thereto and configured to selectively expand radially therefrom, a near-bit reamer disposed proximate the drill bit, the near-bit reamer having cutter blocks coupled thereto and configured to expand therefrom, and a measurement sub configured to measure at least one characteristic of an interior wall of an enlarged wellbore.
In other aspects, embodiments disclosed herein relate to a method of enlarging a wellbore including running a drillstring having a tubular body attached thereto into a wellbore the tubular body comprising an expandable reamer, a drill bit disposed on a distal end of the tubular body, and a near-bit reamer located proximate the drill bit, expanding cutter blocks of the expandable reamer and enlarging a portion of the wellbore, and measuring and recording at least one characteristic of an interior wall of the enlarged portion of the wellbore. The method further includes expanding cutter blocks of the near-bit reamer and enlarging a portion of the wellbore defined between the expandable reamer and the drill bit, wherein enlarging the portion of the wellbore and measuring and recording the at least one characteristic of the interior wall of the enlarged portion of the wellbore occur in the same trip into the wellbore.
Other aspects and advantages of the invention will be apparent from the following description and the appended claims.
In one aspect, embodiments disclosed herein relate to an integrated reamer and measurement tool capable of enlarging a wellbore and measuring the enlarged wellbore in a single trip into the wellbore. As used herein, a “trip” is when the entire drillstring is removed from the well to, for example, replace equipment in the drillstring. Referring initially to
Referring briefly to
The recesses 516 further include angled channels 518 that provide a drive mechanism for the movable tool arms 520 to move axially upwardly and radially outwardly into the expanded position shown in
Below movable arms 520, a drive ring 570 is provided that includes one or more nozzles 575. An actuating piston 530 that forms a piston cavity 535, engages the drive ring 570. A drive ring block 572 connects the piston 530 to the drive ring 570 via bolt 574. The piston 530 is adapted to move axially in the pocket recesses 516. A lower cap 580 provides a lower stop for the axial movement of the piston 530. An inner mandrel 560 is the innermost component within the tool 500, and it slidingly engages a lower retainer 590 at 592. The lower retainer 590 includes ports 595 that allow drilling fluid to flow from the flowbore 508 into the piston chamber 535 to actuate the piston 530.
The movable arms 520 include pads 522, 524, and 526 with structures 700, 800 that engage the wellbore when the arms 520 are expanded outwardly to the expanded position of the tool 500 shown in
Several components are provided for assembly rather than for functional purposes. For example, drive ring 570 is coupled to the piston 530, and then the drive ring block 572 is boltingly connected at 574 to prevent the drive ring 570 and the piston 530 from translating axially relative to one another. The drive ring block 572, therefore, provides a locking connection between the drive ring 570 and the piston 530.
In the expanded position shown in
The drilling fluid flow along path 605, through ports 595 in the lower retainer 590, along path 610 into the piston chamber 535. The differential pressure between the fluid in the flowbore 508 and the fluid in the wellbore annulus 22 surrounding tool 500 causes the piston 530 to move axially upwardly from the position shown in
In certain embodiments, the tool 500 is capable of providing a hydraulic indication at the surface, thereby informing the operator whether the tool is in the contracted position shown in
Referring back to
Cutting head 54 is depicted with a cutting structure 58 including a plurality of polycrystalline diamond compact (“PDC”) cutters 60 and fluid nozzles 62. While drilling assembly 50 depicts a PDC cutting head 54, it should be understood that any cutting assembly known to one of ordinary skill in the art, including, but not limited to, roller-cone bits and impregnated natural diamond bits, may be used. As drilling assembly 50 is rotated and thrust into the formation, cutters 60 scrape and gouge away at the formation while fluid nozzles 62 cool, lubricate, and wash cuttings away from cutting structure 58. Tubular main body 52 includes a plurality of axial recesses 64 into which arm assemblies 66 are located. Arm assemblies 66 are configured to extend from a retracted (shown) position to an extended position (
Arm assemblies 66 travel from their retracted position to their extended position along a plurality of grooves 72 within the wall of axial recesses 64. Corresponding grooves (73 of
In operation, cutting structure 58 is designed and sized to cut a pilot bore, or a bore that is large enough to allow drilling assembly 50 in its retracted (
Preferably, drilling assembly 50 uses hydraulic energy to extend arm assemblies 66 from and into axial recesses 64 within main body 52. Drilling fluid is a necessary component of virtually all drilling operations and is delivered downhole from the surface at elevated pressures through a bore of the drillstring. Similarly, drilling assembly 50 includes a through bore 74, through which drilling fluids flow through drillstring connection 56 and main body 52 and out fluid nozzles 62 of cutting head 54 to lubricate cutters 60. As with other downhole drilling devices, the fluid exiting the bore at the bottom of the drillstring returns to the surface along an annulus formed between the wellbore and the outer profile of the drillstring and any tools attached thereto.
Because of flow restrictions and differential areas between the bore and the annulus of drillstring components, the annulus return pressure is typically significantly lower than the bore supply pressure. This differential pressure between the bore and annulus is referred to as the pressure drop across the drillstring. Therefore, for every drillstring configuration, a characteristic pressure drop exists that may be measured and monitored at the surface. As such, if leaks in drill pipe connections, changes in the drillstring flowpath, or clogs within fluid pathways emerge, an operator monitoring the drillstring pressure drop from the surface will notice a change and may take action if necessary.
Similarly, drilling assembly 50 will desirably exhibit characteristic pressure drop profiles at various stages of operation downhole. When drilling with arm assemblies 66 in their retracted state within axial recesses 64, drilling assembly 50 will exhibit a pressure drop profile corresponding to that retracted state. When the operator desires to extend arm assemblies 66, the pressure and/or flow rate of drilling fluids flowing through bore 74 are increased to exceed a predetermined activation level. Once the activation level is exceeded, a flow switch activates a mechanism that will extend arm assemblies 66. Following such activation, a portion of the drilling fluids are diverted from through bore 74 of main body 52 to the annulus through a plurality of nozzles 76 located adjacent to axial recesses 64. As drilling fluids begin flowing through nozzles 76, the characteristic pressure drop of drilling assembly 50 changes to an intermediate profile such that the operator at the surface is aware the flow switch is activated and underreaming has begun. Once arm assemblies 66 are fully extended, drilling assembly 50 is desirably constructed such that additional flow through an indication nozzle (77 of
When retraction of arm assemblies 66 is desired, the operator reduces (or completely cuts off) the pressure and/or flow rate of drilling fluids through bore 74 to a level below a predetermined reset level. Once decreased to the reset level, internal biasing mechanisms retract arm assemblies 66 and shut off flow between bore 74 and nozzles 76 and 77. Alternatively, the flow of drilling fluids through bore 74 can be cut off altogether. Following retraction, flow through nozzles 76 is halted and the operator may again observe the characteristic pressure drop profile associated with the retracted state across drilling assembly 50 and know that arm assemblies 66 are fully retracted. As with the extension process, an intermediate pressure drop profile will be observed while arm assemblies 66 are in the process of retracting, but not fully retracted. Once the operator observes the “retracted” characteristic pressure drop, they may proceed to raise the pressure and/or flow rate of drilling fluids through drilling assembly 50 up to the activation level without concern for extending arm assemblies 66. Additional description of the near-bit underreamer 120 described herein may be found in U.S. Pat. No. 7,506,787, assigned to the assignee of the present invention, and hereby incorporated by reference in its entirety.
Referring again back to
LWD sensors located in measurement sub 110 may include, for example, one or more of a gamma ray tool, a resistivity tool, an NMR tool, a sonic tool, a formation sampling tool, a neutron tool, and electrical tools. Such tools are used to measure properties of the formation and its contents, such as, the formation porosity, density, lithology, dielectric constant, formation layer interfaces, as well as the type, pressure, and permeability of the fluid in the formation.
One or more MWD sensors may also be located in measurement sub 110. MWD sensors may measure the loads acting on the drill string, such as WOB, TOB, and bending moments. It is also desirable to measure the axial, lateral, and torsional vibrations in the drill string. Other MWD sensors may measure the azimuth and inclination of the drill bit, the temperature and pressure of the fluids in the borehole, as well as properties of the drill bit such as bearing temperature and grease pressure.
The data collected by LWD/MWD tools is often relayed to the surface before being used. In some cases, the data is simply stored in a memory in the tool and retrieved when the tool it brought back to the surface. Any database for storing data may be used. For example, any commercially available database may be used. In addition, a database may be developed for the particular purpose of storing drilling data. In one embodiment, the remote data store uses a WITSML (Wellsite Information Transfer Standard) data transfer standard. Other transfer standards may also be used in accordance with embodiments disclosed herein.
In other cases, LWD/MWD data may be transmitted to the surface using known telemetry methods. The measurement equipment of the measurement sub 110 may be configured to measure and record dimensions of the enlarged wellbore, which may be transmitted to an operator on the surface through an umbilical or other type of data connection (not shown). The data connection may be capable of real-time communication such that data may be transmitted instantaneously. “Real-time” pertains to a data-processing system that controls an ongoing process and delivers its outputs (or controls its inputs) not later than the time when these are needed for effective control. In this disclosure, “in real-time” means that optimized drilling parameters for an upcoming segment of formation to be drilled are determined and returned to a data store at a time not later than when the drill bit drills that segment. The information is available when it is needed. This enables a driller or automated drilling system to control the drilling process in accordance with the optimized parameters. Thus, “real-time” is not intended to require that the process is “instantaneous.”
In certain embodiments, the measurement sub 110 may include one or more devices 108 for measuring parameters related to the shape of the interior wall of the wellbore, more commonly called “calipers.” Caliper apparatus and methods generally include sensors disposed in or on components that are configured to be coupled into a drillstring. It may be desirable to have information concerning the shape of the wellbore wall, for example, for calculating cement volume necessary to cement a pipe of casing in the wellbore. It may also be desirable to know the distance between certain types of sensors and the wall of the wellbore, for example, acoustic, neutron and density sensors. Caliper devices known in the art for use in drill strings include acoustic travel time based devices. An acoustic transducer emits an ultrasonic pulse into the drilling fluid in the wellbore, and a travel time to the wellbore wall back to the transducer of the acoustic pulse is used to infer the distance from the transducer to the wellbore wall. In one embodiment, a drillstring caliper may include a tubular body configured to be coupled within a drillstring. At least one laterally extensible arm is housed in the tubular body. A biasing device may be configured to urge the at least one arm into contact with a wall of a wellbore. A sensor may be configured to generate an output signal corresponding to a lateral extent of the at least one arm.
A method for measuring an internal size of a wellbore according to certain aspects of the present disclosure includes moving a drill string through a wellbore drilled through subsurface formations. At least one contact arm extending laterally from the drill string is urged into contact with a wall of the wellbore. An amount of lateral extension of the arm is translated into corresponding movement of a sensor to generate a signal corresponding to the amount of lateral extension. The method may include at least one of communicating the signal to the Earth's surface and recording the signal in a storage device associated with the drill string.
In some instances it may be desirable to cause the arms of the caliper to contact the wellbore wall only at certain times or under certain conditions. In such case an actuator may be operable by command from the surface to open or close the caliper upon detection of such command. An example control system may be used to operate the caliper according to different drill string configurations and drilling conditions. The sensor or a plurality of such sensors may be in signal communication with a controller such as a programmable general purpose microprocessor or an application specific integrated circuit. The controller may communicate signals from the sensor to a data storage device, such as a hard drive or solid state memory disposed in the tubular body. The controller may be in signal communication with the telemetry communication channel of wired drill pipe, if such is used as the pipe string or the mud flow modulator for communication of selected signals to the recording unit.
In another embodiment, one, two and four caliper arms, typically circumferentially spaced evenly from each other when more than one caliper arm may be used. It should be understood by those skilled in the art that any number of caliper arms structure may be used in accordance with embodiments disclosed herein. The caliper has also been described as being arranged to place the arm(s) in contact with a wall of the wellbore.
Methods related to using the integrated measurement and reamer tool described in accordance with one or more embodiments herein include enlarging a main or deviated wellbore with the primary blocks of the expandable reamer. At the same time, the measurement sub located just above the expandable reamer may activate a number of transducers, which measure the expanded diameter of the enlarged wellbore and stores the data on a memory chip or other storage device and/or communicates the data to the surface. The stored data may be downloaded on a laptop or other user interface on the surface (rig) to confirm the enlarged diameter of the wellbore. In alternate embodiments, the measured data may be transmitted immediately in real-time from the measurement sub to a laptop to confirm the enlarged wellbore.
Additionally, when the reaming interval of the wellbore is completed, the tool may be pulled up sufficiently so that the near-bit reamer is positioned at the end of the enlarged bore (i.e., just above the rat hole indicated by 54 in
Advantageously, embodiments of the present disclosure for an integrated measurement and reamer tool allow an operator to achieve a number of goals in a single trip into the wellbore. First, the main bore may be enlarged, next a diameter of the enlarged bore may be confirmed, and finally, the rat hole may be enlarged. The ability to complete a number of different operations in a single trip reduces drilling and rig costs and drilling time and increases productivity and efficiency.
While the present disclosure has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments may be devised which do not depart from the scope of the disclosure as described herein. Accordingly, the scope of the disclosure should be limited only by the attached claims.