Downhole Tool Centralizing Pistons
The present disclosure is directed to setting pistons designed to centralize downhole tools within a wellbore. In one embodiment, a downhole tool includes a probe extendable to engage a wall of a wellbore and a setting piston extendable towards the wall of the wellbore. A roller is coupled to the setting piston and designed to roll circumferentially along the wall to pivot the downhole tool within the wellbore.
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The disclosure relates generally to pistons that may be employed in downhole tools to position the downhole tools within a wellbore.
Wellbores (also known as boreholes) are drilled to penetrate subterranean formations for hydrocarbon prospecting and production. During drilling operations, evaluations may be performed on the subterranean formation for various purposes, such as to locate hydrocarbon-producing formations and manage the production of hydrocarbons from these formations. To conduct formation evaluations, the drill string may include one or more drilling tools that test and/or sample the surrounding formation, or the drill string may be removed from the wellbore, and a wireline tool may be deployed into the wellbore to test and/or sample the formation. These drilling tools and wireline tools, as well as other wellbore tools conveyed on coiled tubing, slick line, drillpipe, casing or other conveyers, are also referred to herein as “downhole tools.”
Formation evaluation often requires that fluid from the formation be drawn into the downhole tool for testing and/or sampling. Various fluid communication devices, such as probes, are typically extended from the downhole tool and placed in contact with the wellbore wall to establish fluid communication with the formation surrounding the wellbore and to draw fluid into the downhole tool. The probe may include a packer that establishes a seal with the sidewall of a wellbore. However, the inability to centralize the downhole tool in the wellbore may result in an incomplete seal.
The present disclosure is best understood from the following detailed description when read with the accompanying figures. It is emphasized that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.
It is to be understood that the present disclosure provides many different embodiments, or examples, for implementing different features of various embodiments. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting.
The present disclosure is directed to pistons that may be employed to centralize downhole tools within a wellbore. According to certain embodiments, the pistons may include rollers designed to centralize the tool within the wellbore. For example, the rollers may include wheels designed to roll along the circumference of the wellbore wall to centralize the tool along a longitudinal axis of the wellbore. In certain embodiments, the downhole tool may pivot around a probe extended toward an opposite side of the wellbore from the centralizing pistons.
The drillstring 106 is rotated by a rotary table 110, energized by means not shown, which engages a kelly 112 at the upper end of the drillstring 106. The drillstring 106 is suspended from a hook 114, attached to a traveling block (also not shown), through the kelly 112 and a rotary swivel 116 that permits rotation of the drillstring 106 relative to the hook 114. The rig 100 is depicted as a land-based platform and derrick assembly used to form the wellbore 104 by rotary drilling.
Drilling fluid or mud 118 is stored in a pit 120 formed at the well site. A pump 122 delivers the drilling fluid 118 to the interior of the drillstring 106 via a port in the swivel 116, inducing the drilling fluid to flow downwardly through the drillstring 106 as indicated by a directional arrow 124. The drilling fluid exits the drillstring 106 via ports in the drill bit 108, and then circulates upwardly through the region between the outside of the drillstring and the wall of the wellbore, called the annulus, as indicated by directional arrows 126. The drilling fluid lubricates the drill bit 108 and carries formation cuttings up to the surface as it is returned to the pit 120 for recirculation.
The downhole tool 102, sometimes referred to as a bottom hole assembly (“BHA”), is preferably positioned near the drill bit 108 and includes various components with capabilities, such as measuring, processing, and storing information, as well as communicating with the surface. A telemetry device (not shown) is also preferably provided for communicating with a surface unit (not shown).
The downhole tool 102 further includes a sampling while drilling (“SWD”) system 128 including a fluid communication module 130 and a sampling module 132. The modules are preferably housed in a drill collar for performing various formation evaluation functions, such as pressure testing and sampling, among others. As shown in
The fluid communication module 130 includes a probe 134, which may be positioned in a stabilizer blade or rib 136. The probe 134 includes an inlet for receiving formation fluid and a flowline (not shown) extending into the downhole tool for passing fluids through the tool. The probe 134 is preferably movable between extended and retracted positions for selectively engaging a wall of the wellbore 104 and acquiring fluid samples from the formation F. One or more setting pistons 138 may be provided to assist in positioning the fluid communication device against the wellbore wall. As discussed further below with respect to
The formation fluid may be expelled through a port (not shown) or it may be sent to one or more fluid sampling modules 226 and 228. In the illustrated example, the electronics and processing system 206 and/or a downhole control system are configured to control the extendable probe assembly 216 and/or the drawing of a fluid sample from the formation F. As discussed further below with respect to
The piston assembly 300 is designed to centralize the downhole tool 302 within the wellbore 304. As shown in
The probe assembly 306 includes an extension member 308 designed to radially extend from and retract towards the downhole tool 302. Accordingly to certain embodiments, the extension member 308 may be hydraulically or mechanically actuated. A plate 310 is disposed on the end of the extension member 308 to mount a packer 312. According to certain embodiments, the packer 312 may be a rubber gasket, or other rubber-like material, designed to sealingly engage the wall 313 of the wellbore 304. Formation fluid may enter the probe assembly 306 through an inlet 314 in the packer 312, and the formation fluid may be directed into the downhole tool 302 for testing and/or sampling.
The piston assembly 300 is also designed to extend from and retract towards the downhole tool 302. The piston assembly 300 includes a piston 316 that may be actuated to extend radially outward from the downhole tool 302 to engage the opposite side of the wall 313, which in turn may force the packer 312 towards the wall 313. According to certain embodiments, the piston assembly 300 may be designed to promote a good seal between the packer 312 and the wall 313 by forcing packer 312 towards the wall 313. The piston assembly 300 further includes a roller 318 coupled to the piston 316. For example, the roller 318 may be rotatably coupled to the end of the piston 316 by a bearing 320. The bearing 320 may facilitate rotation of the roller 318 and further may seal the interior of the piston 316 from debris and other fluid that may be disposed within the wellbore 304. Further, the bearing 320 may have a rugged construction designed to withstand the setting force of the piston assembly 300, which in certain embodiments may be approximately 5000 lbs.
As shown in
As shown in
When the piston assemblies 300 are retracted, the rollers 318, and in particular, the hemispherical wheels 334, may extend beyond the housing 356. Accordingly, the downhole tool 352 may include standoffs 366 that extend radially from the housing 356 to protect the rollers 318 during insertion of the downhole tool 352 into the wellbore 354. The standoffs 366 may be radially aligned with the piston assemblies 300 and may be designed to radially extend from the housing beyond the rollers 318 when the pistons are retracted. According to certain embodiments, the standoffs 366 may be bolted, clamped, or otherwise affixed to the housing 356. Further, the standoffs 366 may be disposed longitudinally on both sides of a roller 318. In other embodiments, the rollers 318 may be designed to fully retract within the housing 356 and the standoffs 366 may be omitted. Further, in certain embodiments, the rollers 318 may be disposed between stabilizer blades 112, which may function as standoffs to protect the rollers 318.
In certain embodiments, the rollers may then be locked (block 378) to inhibit further movement or pivoting of the tool within the wellbore. For example, as shown in
According to certain embodiments, the housing 356 may include one or more grooves that contain bearings 384 that rotatably couple the rollers 382 to the housing 356. The rollers 382 may rotate with respect to the housing 356, as generally shown by the arrow 386, and may roll along the surface of the wall 313. The rollers 382 may be constructed of metal, rubber, or other suitable material designed to engage the wall 313. The outer surface of the rollers 382 may include grooves 388 designed to provide friction between the rollers 382 and the wall 313.
When the probe assembly 306 is extended towards the wall 313, the rollers 382 may roll along the wall to pivot the downhole tool in the wellbore. The downhole tool may pivot in a manner similar to that described above with respect to
As shown in
The foregoing outlines features of several embodiments so that those skilled in the art may better understand the aspects of the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions and alterations herein without departing from the spirit and scope of the present disclosure.
Claims
1. A downhole tool comprising:
- a probe extendable to engage a wall of a wellbore;
- a setting piston extendable towards the wall of the wellbore; and
- a roller coupled to the setting piston and configured to roll circumferentially along the wall to pivot the downhole tool within the wellbore.
2. The downhole tool of claim 1, wherein the probe comprises a packer to sealingly engage the wall and an inlet to direct formation fluid into the downhole tool.
3. The downhole tool of claim 1, wherein the roller comprises an outer diameter greater than and an outer diameter of the setting piston.
4. The downhole tool of claim 1, wherein the roller comprises a grooved wheel.
5. The downhole tool of claim 1, wherein the roller comprises a plurality of hemispheres coupled to the setting piston by a bearing extending between the plurality of hemispheres.
6. The downhole tool of claim 1, wherein the roller is configured to pivot the downhole tool about a contact point between the probe and the wall.
7. The downhole tool of claim 1, wherein the setting piston is disposed radially opposite from the probe.
8. The downhole tool of claim 1, wherein the roller comprises a single wheel disposed in a housing coupled to an end of the setting piston.
9. The downhole tool of claim 1, wherein the roller is configured to centralize the downhole tool along a longitudinal axis of the wellbore.
10. A method for centralizing a downhole tool comprising:
- extending a probe of the downhole tool to engage a wall of a wellbore;
- extending a setting piston of the downhole tool such that a roller coupled to the setting piston engages the wall; and
- rolling the roller circumferentially along the wall to pivot the downhole tool within the wellbore.
11. The method of claim 10, wherein extending a probe and extending a setting piston occur simultaneously.
12. The method of claim 10, wherein rolling the roller comprises rolling a plurality of hemispheres along the wall.
13. The method of claim 10, wherein extending a probe comprises disposing a packer against the wall.
14. The method of claim 10, comprising locking the roller to inhibit movement of the roller along the wall.
15. A downhole tool comprising:
- a probe extendable from a housing of the downhole tool to engage a wall of a wellbore;
- a setting piston extendable from the housing at a location radially opposite the probe; and
- a roller coupled to the setting piston and configured to roll circumferentially along the wall to pivot the downhole tool within the wellbore.
16. The downhole tool of claim 15 comprising an additional setting piston extendable from the housing at another location radially opposite the probe.
17. The downhole tool of claim 15, wherein the housing comprises a recess that houses the setting piston in a retracted position.
18. The downhole tool of claim 15, comprising one or more standoffs coupled to the housing and radially aligned with the setting piston.
19. The downhole tool of claim 18 wherein the one or more standoffs project from the housing such that the one or more standoffs radially extend beyond the roller when the setting piston is retracted.
20. The downhole tool of claim 15 comprising a pair of standoffs coupled to the housing and each radially aligned with the setting piston.
Type: Application
Filed: Dec 20, 2012
Publication Date: Jun 26, 2014
Applicant: SCHLUMBERGER TECHNOLOGY CORPORATION (Sugar Land, TX)
Inventor: Edward Harrigan (Richmond, TX)
Application Number: 13/721,660
International Classification: E21B 23/01 (20060101);