Reliable Sleeve Activation for Multi-Zone Frac Operations Using Continuous Rod and Shifting Tools
An apparatus for opening and closing downhole tools, such as sliding sleeves, includes a first (opening) shifting tool connected to an end of a continuous rod, an intermediate rod connected below the first shifting tool, and a second (closing) shifting tool connected to the end of the intermediate rod. The first tool has a profile for selectively opening sleeves when moved downhole, and the second tool has a profile for selectively closing sleeves when moved uphole. Alternatively, a single tool can couple to the end of the continuous rod and can have the profiles for opening and closing sleeves. When used, the continuous rod and shifting tools are deployed downhole to a series of sliding sleeves on a tool string. Manipulated by the continuous rod and a rig at the surface, the shifting tools are used to successively open and close the sliding sleeves so that successive isolated zones of a formation can be treated with frac fluid.
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Selectively fracing multiple zones of a formation improves the production capabilities of a well. The equipment string for such a frac operation uses a series of packers to sequentially isolate different zones of a downhole formation. Sliding sleeves on the tubing string position between each of the packers and provide exit ports for frac fluid to interact with the adjacent zones of the formation. Performing successive frac treatments on the isolated zones requires the sliding sleeves to be opened and closed in a desired sequence so that zones of interest can be fraced independently of the other zones. To do this, the frac operation uses several steps. First, one sliding sleeve is opened, while the others remain closed. Frac fluid is pumped downhole and through the open sleeve to interact with the adjacent zone of the formation. When facing is done for this zone, the sliding sleeve is then closed, and another sliding sleeve is opened so the next zone can be treated.
Sliding sleeves can be activated using many types of devices, including balls, darts, and pulling tools. Currently, operators experience problems when performing frac operations For example, the number of zones that can be treated may be limited by the method used to actuate the sleeves. Also, operators can have difficulties ensuring that the proper sleeve is open for the frac treatment and then that the proper sleeve is closed and sealed after that treatment. This difficulty can be even more problematic when fracing a horizontal well.
When balls are used to actuate the sliding sleeves, for example, the frac treatment is applied successively to each isolated zones by selectively opening the sliding sleeves and allowing the treatment fluid to interact with the adjacent zones of the formation. To open each sliding sleeve, operators drop a specifically sized ball into the tubing string and land the ball on a corresponding ball seat on a designated sliding sleeve. Once seated, the ball closes off the lower zone just treated, and built up pressure on the seated ball forces the sliding sleeve open so frac fluid can interact with the adjacent zone of the formation. Operators repeat this process up the tubing string by successively dropping larger balls against larger ball seats in the sliding sleeves.
The required diameters of the ball seats and the required increments between ball sizes limits how many zones can be treated using balls to open the sliding sleeves. For example, the lowermost ball seat must be the smallest, and each shallower seat must be sized slightly larger. In general, the balls can range in size from 1-in. to 3¾-in. Therefore, only a finite number of frac zones can be successfully used when opening the sleeves with balls due to the needed increments between ball sizes to differentiate them from one another. Therefore, actuating sliding sleeves with balls is not practical for frac operations involving several (e.g., more than about eleven) frac zones. In addition to the limit on the number of frac zones that can be handled, using balls and darts to open sliding sleeves only allows for one shot operations. In other words, the balls and darts are only capable of opening the sleeves, which cannot be closed unless another device is used. Finally, any balls and darts used to operate sleeves must be removed either by floating or milling them, which involves time and expense to perform.
Other than balls and darts, a pulling tool connected to wireline can be used to actuate sliding sleeves during a frac operation. However, actuating sliding sleeves using wireline can be limited in horizontal sections downhole. In many cases, wireline has no real pushing capabilities, which limits its use in operating sliding sleeves or other flow control systems within a wellbore.
Using coiled tubing can overcome the limitations of wireline. Unfortunately, a pulling tool on coiled tubing can still have limited access in extended horizontal wellbores, making it difficult for the pulling tool to reach sliding sleeves in horizontal sections. This difficulty is due at least in part to the fact that coiled tubing has some memory inherent in its material. Therefore, the coiled tubing as it is run downhole with the pulling tool is more likely to produce friction within the tubing string in which it is run, making moving the coiled tubing and the pulling tool more difficult. When used under these circumstances, the coiled tubing requires operators to spend an excessive amount of time to locate and subsequently open or close a sliding sleeve—sometime without success altogether. Furthermore, coil tubing is expensive and is preferably removed from the tubing string with each frac treatment to avoid damage to the coil tubing. Finally, the physical nature of coiled tubing inherently limits the coil tubing's ability to operate sliding sleeves by pushing. All of these issues greatly increase the time and cost of performing a frac operation with coiled tubing and make coiled tubing less desirable for operating sliding sleeves.
What is needed is a solution for cycling sliding sleeves open and closed in extended horizontal applications that can be better manipulated from the surface and that is more reliable in opening and closing the sleeves downhole.
A system 10 schematically shown in
As shown, the cased borehole 12 can have an extended horizontal section that makes actuating the sliding sleeves 50 difficult with conventional coiled tubing or wireline techniques. To overcome these difficulties, the tool actuating device 60 is disposed on the distal end of the continuous rod 40, and the rod 40 and device 60 are used together to effectively and reliably open and close the sliding sleeves 50 in such an extended horizontal section. (The system 10 can be used equally as well in vertical applications). In general, the tool actuating device 60 can be moved up or down in the string 14 to selectively actuate a given sleeve 50 between opened and closed conditions by engaging specific profiles on the device 60 with profiles in the sleeve 50. The rigid continuous rod 40 stiffly conveys the desired movement of the device 60 relative to the sleeves 50, making the opening and closing of the sleeves 50 more predictable and ensuring that more complete travel of the sleeves 50 is achieved.
As noted previously, coiled tubing has some memory inherent in its material and produces undesirable friction when conveyed in a horizontal borehole. As a result, operators must spend an unwarranted amount of time attempting to locate and actuate the sliding sleeves downhole—sometimes with no success. However, the continuous rod 40 attempts to straighten out in the tubing string 14 and produces a lower friction component. The reduced friction allows operators to move the tool actuating device 60 as needed with better control from the surface. In this way, the rod 40 and device 60 facilitate frac operations in the horizontal length of the borehole.
As shown, the continuous rod 40 deploys in the tool string 14 to convey the device 60 downhole to the sliding sleeves 50. At the surface, a rig 30 for extended continuous rod is used to manipulate (raise and lower) the continuous rod 40 in the string 14 and thereby move the actuating device 60 relative to the sliding sleeves 50. This rig 30 can be similar to that used with extended continuous rod. For example, the rig 30 can include a reel for the continuous rod 40 and a variable-speed, hydraulically driven gripper mechanism (not shown), and the rig 30 can be adapted to operate like a heavy duty slickline unit at the surface to deploy the continuous rod 40 and device 60 downhole. In addition to the rig 30, other components (not shown), such as wellhead, lubricator, etc., are also used at the surface.
The sliding sleeves 50 can be selectively opened and closed to divert frac fluid in the tubing string 14 to the isolated zone of the annulus 15 between packers 20. An example sliding sleeve 50 shown in
To move the insert 54 between the opened and closed conditions, the insert 54 has a lower profile 56 and an upper profile 58 that allow the insert 54 to be engaged and moved within the housing 52. For the present sleeve 50, the lower profile 56 is used to move the insert 54 downward in the housing 52, thereby closing the sleeve 50. By contrast, the upper profile 58 is used to move the insert 54 upward in the housing 52, thereby opening the sleeve 50. A reverse arrangement is also possible in which upward movement of the insert 54 by the upper profile 58 can close the sleeve 50 and downward movement by the lower profile 56 can open the sleeve 50.
With an understanding of the system 10, continuous rod 40, sliding sleeves 50, and tool actuating device 60 provided above, discussion now turns to a more detailed description of the tool actuating device 60. As shown in
In the present example, the upper tool 100 is designed to be the opening tool for opening the sliding sleeves 50 by engaging the upper profile (58) and shifting the insert (54) upward in the housing (50). (See
The upper (opening) shifting tool 100 shown in
As shown in
As with upper tool 100, the lower (closing) shifting tool 200 shown in
Operation of the upper tool's B-profile 122 in opening a sliding sleeve 50 is shown in
Operation of the lower tool's B-profile 222 in closing the sliding sleeve 50 is shown in
As discussed above, the continuous rod 40 and tool actuating device 60 can be deployed by a surface rig 30 to open and close sliding sleeves during a frac operation. In stages of a frac operation shown in
As initially shown in
When lowered, the tools 100/200 are passed through each of the sliding sleeves 50A-C, which are initially installed closed on the string 14. The sleeves 50A-C may be deployed with grease or other material packed inside to maintain the sliding inserts (54) in the closed condition in the sleeves 50A-C during deployment. As the tools 100/200 are deployed downhole, they cam past each of the sleeves' inserts (54) without engaging the profiles (56, 58). Eventually, the upper (opening) tool 100 passes into the lowermost sliding sleeve 50A. Using a upward jarring movement, the upper (opening) tool 100 opens the lowermost sliding sleeve 50A by engaging the collet's B-profiles (122) into the insert's upper recess (58) (See
As then shown in
During treatment, the frac fluid diverts through the open sleeve 50A and treats the adjacent isolated zone though the perforations 13. Once this zone has been treated, operators use the rig to lift the continuous rod 40 in the string 14. As shown in
As shown in
Although the frac operation discussed above involved opening the sleeves 50 in the uphole direction and closing them in the downhole direction, the reverse arrangement could be used. Likewise, treatment of successive zones could proceed successively from the uppermost zone to the lowermost zone or could be performed selectively at any of the various zones. In addition, although the device 60 and continuous rod 40 are initially deployed from the surface downhole to the lowermost sleeve 50A in the above discussion, it is also possible to deploy the device 60 independently in a bottomhole assembly (not shown) coupled in a conventional manner to the tubing string 14 below the lower most sliding sleeve 50A. In this case, the continuous rod 40 can then be deployed downhole with a suitable coupling known in the art to connect to the device 60 and retrieve if from the bottomhole assembly to conduct the successive frac operations up the wellbore.
The tool actuating device 60 of
In general, the continuous rod 40 used with the system 10 can be COROD® and can have similar properties and characteristics. (COROD is a registered trademark of Weatherford/Lamb Inc.—the assignee of the present disclosure). For example, the continuous rod 40 can be composed of carbon steel, chromium-molybdenum alloy steel (e.g., AISI 4142), or other suitable material and can have round or semi-elliptical cross-section with a diameter ranging from 12/16-inch to 18/16-inch, for example.
As shown in
Although the system 10 has been described for opening and closing sliding sleeves on a frac string, the system of continuous rod 40 and tool actuating device 60 can also be used to actuate other downhole tools that can be actuated to a first operative condition in a first direction and to a second operative condition in a second direction. Some other suitable downhole tools include, for example, a gravel pack closing sleeve, a completion isolation valve, or other downhole tool having shiftable operation. With any of these downhole tools, the ability to actuate the tool with the continuous rod 40 and actuating device 60 can be enhanced by the reliable and efficient operation that the rod 40 and device 60 offer in either vertical or horizontal wells.
The foregoing description of preferred and other embodiments is not intended to limit or restrict the scope or applicability of the inventive concepts conceived of by the Applicants. In exchange for disclosing the inventive concepts contained herein, the Applicants desire all patent rights afforded by the appended claims. Therefore, it is intended that the appended claims include all modifications and alterations to the full extent that they come within the scope of the following claims or the equivalents thereof.
Claims
1. A downhole tool actuating method, comprising:
- installing a first shifting tool to an end of a continuous rod, the first shifting tool adapted to selectively actuate a downhole tool in a first direction to a first operative condition;
- installing an intermediate rod below the first shifting tool;
- installing a second shifting tool to an end of the intermediate rod, the second shifting tool adapted to selectively actuate a downhole tool in a second direction to a second operative condition;
- deploying the continuous rod and the first and second shifting tools downhole to a downhole tool; and
- selectively actuating the downhole tool to either the first or the second operative condition by moving the first and second shifting tools with the continuous rod in either the first or second directions relative to the downhole tool to selectively actuate the downhole tool with either the first or second shifting tool.
2. The method of claim 1, wherein the downhole tool is a sliding sleeve having an insert movable between opened and closed conditions.
3. The method of claim 1, wherein installing the first shifting tool to the end of the continuous rod comprises coupling a first threaded pin on the continuous rod to a second threaded pin on the first shifting tool using a sucker rod connector.
4. The method of claim 1, wherein installing the intermediate rod comprises coupling a first threaded pin of a sucker rod to a second threaded pin of the first shifting tool using a sucker rod connector.
5. The method of claim 1, wherein selectively actuating the downhole tool to the first operative condition comprises:
- engaging an uphole facing shoulder on the first shifting tool against a downhole facing shoulder on the downhole tool; and
- selectively actuating the downhole tool to an opened condition by moving the first shifting tool in an uphole direction.
6. The method of claim 5, wherein selectively actuating the downhole tool to the opened condition further comprises camming the uphole facing shoulder free from the downhole facing shoulder against a first stop shoulder in the downhole tool.
7. The method of claim 5, wherein selectively actuating the downhole tool to the second operative condition comprises:
- engaging a downhole facing shoulder on the second shifting tool against an uphole facing shoulder on the downhole tool; and
- selectively actuating the downhole tool to a closed condition by moving the second shifting tool in a downhole direction.
8. The method of claim 7, wherein selectively actuating the downhole tool to the closed condition further comprises camming the downhole facing shoulder free from the uphole facing shoulder against a second stop shoulder in the downhole tool.
9. A sliding sleeve actuating method, comprising:
- installing at least one shifting tool on an end of a continuous rod, the at least one shifting tool adapted to selectively actuate a downhole tool in a first direction to a first operative condition and in a second direction to a second operative condition;
- deploying the continuous rod and the at least one shifting tool downhole to a downhole tool; and
- selectively actuating the downhole tool to either the first or second operative condition by moving the at least one shifting tool with the continuous rod in either the first or second directions relative to the downhole tool to selectively actuate the downhole tool with the at least one shifting tool.
10. The method of claim 9, wherein selectively actuating the downhole tool to the first operative condition comprises:
- engaging a first shoulder on the at least one shifting tool facing a first direction against a second shoulder on the downhole tool facing a second opposite direction; and
- selectively actuating the downhole tool to the first operative condition by moving the at least one shifting tool in the first direction.
11. The method of claim 10, wherein selectively actuating the downhole tool to the first operative condition further comprises camming the first shoulder free from the second shoulder against a first stop shoulder in the downhole tool.
12. The method of claim 10, wherein selectively actuating the downhole tool to the second operative condition comprises:
- engaging a second shoulder on the shifting tool facing the second direction against a first shoulder on the downhole tool facing the first opposite direction; and
- selectively actuating the downhole tool to the second operative condition by moving the at least one shifting tool in the second direction.
13. The method of claim 12, wherein selectively actuating the downhole tool to the second operative condition further comprises camming the second shoulder free from the first shoulder against a second stop shoulder in the downhole tool.
14. A formation fracing method, comprising:
- deploying a continuous rod downhole to a plurality of sliding sleeves, the continuous rod having at least one shifting tool adapted to selectively open and close a sliding sleeve in opposing first and second directions;
- selectively opening and closing the sliding sleeves by moving the at least one shifting tool with the continuous rod in the first and second opposing directions relative to the sliding sleeves; and
- fracing selective zones of the formation isolated by packers disposed downhole between each of the sliding sleeves by using the at least one shifting tool and the continuous rod to successively open and close the sliding sleeves in the selective zones.
15. The method of claim 14, wherein deploying the continuous rod downhole comprises installing one shifting tool on an end of the continuous rod, the one shifting tool adapted to selectively open the sliding sleeve in the first direction and to selectively close the sliding sleeve in the second direction.
16. The method of claim 14, wherein deploying the continuous rod downhole comprises:
- installing a first shifting tool to an end of the continuous rod;
- installing an intermediate rod below the first shifting tool; and
- installing a second shifting tool to an end of the intermediate rod.
17. The method of claim 16, wherein the first shifting tool is adapted to selectively open the sliding sleeve in the first direction, and wherein the second shifting tool is adapted to selectively close the sliding sleeve in the second direction.
18. A downhole tool actuating system, comprising:
- a continuous rod having a distal end;
- a surface rig operable to deploy and move the continuous rod in first and second directions downhole; and
- a tool actuating device coupleable to the distal end of the continuous rod, the tool actuating device having a first profile adapted to selectively actuate a downhole tool in the first direction to a first operative condition, the tool actuating device having a second profile adapted to selectively actuate the downhole tool in the second direction to a second operative condition.
19. The system of claim 18, wherein the tool actuating device comprises:
- a first shifting tool coupleable to the distal end of the continuous rod and having the first profile;
- an intermediate rod having first and second ends, the first end coupleable to the first shifting tool; and
- a second shifting tool coupleable to the second end of the intermediate rod and having the second profile.
20. The system of claim 18, wherein the tool actuating device comprises a shifting tool coupleable to the distal end of the continuous rod, the shifting tool having the first and second profiles.
Type: Application
Filed: Oct 31, 2008
Publication Date: May 6, 2010
Applicant: WEATHERFORD/LAMB, INC. (Houston, TX)
Inventor: James F. Wilkin (Sherwood Park)
Application Number: 12/262,268
International Classification: E21B 34/14 (20060101);