Isolation bypass transition joint

[0001] The present invention relates generally to operations performed in conjunction with subterranean wells and, in an embodiment described herein, more particularly provides a method of completing a well utilizing an isolation bypass transition joint.

[0002] One method of completing a well having an intersection between a parent wellbore and a branch wellbore is to position a liner at the intersection, so that an upper end of the liner is in the parent wellbore and a lower end of the liner is in the branch wellbore. The liner may or may not be cemented in place by flowing cement about the liner at the wellbore intersection.

[0003] In transitioning laterally from the parent wellbore to the branch wellbore, the liner extends across the parent wellbore. To permit flow through the parent wellbore from below to above the wellbore intersection, a sidewall of the liner is typically perforated using conventional perforating guns equipped with a device which aims the guns to shoot through the sidewall in a desired direction. Another method is to mill through the liner sidewall using a deflection device positioned in the liner. However, the use of explosives is very hazardous and milling operations are quite time-consuming.

[0004] It would be desirable to provide an improved method which does not require the use of explosives, with their inherent dangers, and which does not require milling through the liner sidewall to provide fluid communication therethrough.

[0005] In carrying out the principles of the present invention, in accordance with an embodiment thereof, a method is provided which utilizes a specially configured isolation bypass transition joint. The transition joint is used in a liner string assembly at the intersection between a parent and branch wellbore.

[0006] In one aspect of the invention, the transition joint includes two tubular strings, one inside of the other. An annular space is formed between the tubular strings. When installed at the wellbore intersection, a sidewall portion of the transition joint extends across the parent wellbore.

[0007] In another aspect of the invention, one or more plug devices are disposed in the transition joint sidewall when it is installed. The plug devices are opened to permit flow through the transition joint sidewall. The plug devices may be opened, for example, by cutting a portion of each of the devices, by dissolving a portion of each of the devices, etc.

[0008] In yet another aspect of the invention, the plug devices prevent flow through the transition joint sidewall prior to being opened. The plug devices may also isolate the annular space from the interior and exterior of the transition joint. The plug devices may continue to isolate the annular space from the interior and exterior of the transition joint after being opened.

[0009] In still another aspect of the invention, cement is flowed through the annular space, and the plug devices prevent the cement from flowing laterally out of the transition joint sidewall. After the cement has hardened, the plug devices are opened to permit flow through the transition joint sidewall. The plug devices may include generally tubular hollow portions extending from the inner tubular string to the outer tubular string.

[0010] These and other features, advantages, benefits and objects of the present invention will become apparent to one of ordinary skill in the art upon careful consideration of the detailed description of a representative embodiment of the invention hereinbelow and the accompanying drawings.

[0011] FIG. 1 is a schematic cross-sectional view of a method embodying principles of the present invention;

[0012] FIG. 2 is a cross-sectional view of the method of FIG. 1, wherein additional steps of the method have been performed.

[0013] Representatively illustrated in FIG. 1 is a method 10 which embodies principles of the present invention. In the following description of the method 10 and other apparatus and methods described herein, directional terms, such as above, below, upper, lower, etc., are used only for convenience in referring to the accompanying drawings. Additionally, it is to be understood that the various embodiments of the present invention described herein may be utilized in various orientations, such as inclined, inverted, horizontal, vertical, etc., and in various configurations, without departing from the principles of the present invention.

[0014] As depicted in FIG. 1, some steps in the method 10 have already been performed. A casing string 12 has been installed and cemented in a parent wellbore 14. A branch wellbore 16 has been drilled extending outward from the parent wellbore 14 by deflecting cutting tools, such as mills, reamers, drills, etc. off of a whipstock 18 positioned in the parent wellbore below the intersection between the parent and branch wellbores.

[0015] Mills, reamers, etc. may be deflected off of the whipstock 18 to form a window 20 laterally through the casing string 12. The window 20 could alternatively be preformed in the casing string 12. For example, the window 20 could have a relatively easily milled or drilled covering (e.g., an outer aluminum sleeve) or filling therein (e.g., a fiberglass insert) which is removed when the branch wellbore 16 is drilled.

[0016] After drilling the branch wellbore 16, a liner string assembly 22 is conveyed into the parent wellbore 14. A lower end of the assembly 22 is deflected off of the whipstock 18 and into the branch wellbore 16. A packer 24 (preferably, an inflatable packer) is set in the branch wellbore 16, and a packer/liner hanger 26 is set in the parent wellbore 14.

[0017] The packer/liner hanger 26 secures the assembly 22 in position and radially oriented as depicted in FIG. 1. However, other means may be used to position and/or orient the assembly 22. For example, an orienting latch coupling of the type well known to those skilled in the art may be installed in the casing string 12, an abutment or shoulder 23 on the assembly 22 may engage the casing at the window 20, thereby preventing further displacement of the assembly through the window, etc. As another example, a projection, shoulder, abutment or other engagement device (which may be similar in some respects to the abutment 23) may engage the whipstock 18, instead of, or in addition to, engaging the casing 12 at the window 20.

[0018] For this purpose, the whipstock 18 could include an upwardly extending tubular neck through which the assembly 22 is displaced before the whipstock deflects the lower end of the assembly into the branch wellbore 16. The abutment or shoulder 23 on the liner assembly 22 could engage this whipstock 18 upper neck to position the assembly properly with respect to the window 20 and branch wellbore 16. This engagement could also radially orient the assembly 22 relative to the whipstock 18 if the neck is provided with an orienting profile, such as an orienting latch. In addition, wireline tools, pipe tallies, pip tags, etc. may be used to determine the location of the liner assembly 22 relative to the window 20.

[0019] The abutment 23 preferably circumscribes the liner assembly 22 and extends radially outward therefrom, in the nature of a flange. This flanged abutment 23 may serve to prevent debris from the branch wellbore 16 from entering the parent wellbore 14 and accumulating about the whipstock 18, as well as serving to aid in the positioning of the liner assembly 22.

[0020] The assembly 22 includes a transition joint 28 which is positioned at the intersection between the parent and branch wellbores 14, 16. The transition joint 28 includes an inner tubular string 30 and an outer tubular string 32, with an annular space 34 formed therebetween. Several plug devices 36, 38, 40 are disposed in a sidewall of the transition joint 28 where it extends laterally across the parent wellbore 14. The plug devices 36, 38, 40 are radially oriented so that they are opposite the whipstock 18.

[0021] The plug devices 36, 38, 40 are used to selectively permit flow through the transition joint 28 sidewall. Although three of the plug devices 36, 38, 40 are depicted in FIG. 1, it is to be understood that any number of plug devices, including one, could be used.

[0022] The plug devices 36, 38, 40 are merely illustrated in FIG. 1 as examples of the wide variety of plug devices which may be used. The plug devices 36, 38, 40 could also be differently configured or positioned in the liner assembly 22 in keeping with the principles of the invention. For example, the plug devices 36, 38, 40 are oriented so that fluid flows through them in a radial direction relative to the liner assembly 22 as depicted in FIG. 1, but the plug devices could be oriented so that fluid flows through them in the same direction as fluid flow through the whipstock 18, i.e., in a vertical direction as viewed in FIG. 1.

[0023] The plug device 36 has a generally tubular and hollow body extending between the inner and outer strings 30, 32. A cap 42, which extends into the interior of the inner string 30, closes off one end of the plug device 36. When the cap 42 is cut off, the plug device 36 is opened to flow therethrough.

[0024] The plug device 38 also has a generally tubular and hollow body extending between the inner and outer strings 30, 32. A dissolvable plug 44, which extends into the interior of the inner string 30, closes off one end of the plug device 36. When the plug 44 is dissolved, the plug device 38 is opened to flow therethrough.

[0025] The plug device 40 also has a generally tubular body extending between the inner and outer strings 30, 32. However, a dissolvable plug 46 prevents fluid flow through the body of the plug device 40. When the plug 46 is dissolved, the plug device 40 is opened to flow therethrough.

[0026] Of course, many other types of plug devices could be used. For example, the entire plug device could be dissolvable, the plug device could be opened in other ways, such as by pushing the plug device through the transition joint 28 sidewall, etc. Thus, the description of the specific plug devices 36, 38, 40 in the exemplary method 10 is not to be taken as limiting the principles of the invention.

[0027] After the assembly 22 is positioned as depicted in FIG. 1, cement is flowed through the assembly. As used herein, the term cement, cementing, and similar terms, are used to designate any manner of securing and/or sealing a tubular string in a wellbore by flowing a hardenable substance thereabout. The substance may be cementitious, may be a hardenable gel, polymer resin, such as epoxy, etc.

[0028] The cement is flowed downwardly through the inner tubular string 30 as indicated by the arrows 48, from the parent wellbore 14 to the branch wellbore 16. The cement then flows outwardly through conventional stage cementing equipment (not shown) and upwardly between the tubular string 30 and the branch wellbore 16 as indicated by arrows 52. The arrows 52, and another arrow 50, also indicate how the cement flows upwardly in the annular space 34 between the tubular strings 30, 32 in the transition joint 28.

[0029] As the cement flows through the annular space 34, the plug devices 36, 38, 40 prevent the cement from flowing outward from the annular space, either to the interior or to the exterior of the transition joint 28. The plug devices 36, 38, 40 also prevent the cement being delivered into the branch wellbore 16 (as indicated by arrows 48) from flowing into the annular space 34, or from flowing through the plug devices to the parent wellbore 14 below the wellbore intersection.

[0030] The cement flows from the annular space 34 outwardly to an annulus between the inner string 30 and the wellbore 14 as indicated by arrows 54. From this annulus, the cement may flow upwardly through a passage in the packer/liner hanger 26 according to conventional cementing practice.

[0031] Thus, the assembly 22 is cemented in the parent and branch wellbores 14, 16 by delivering the cement through the inner string 30 and returning the cement via the annular space 34. The plug devices 36, 38, 40 facilitate this process by isolating the cement delivery and return flows, while preventing the cement from flowing into the parent wellbore 14 below its intersection with the branch wellbore 16.

[0032] Swab cups 56, or another suitable sealing device, prevent the cement returned to the annulus between the inner string 30 and the parent wellbore 14 from flowing downwardly in the parent wellbore to its intersection with the branch wellbore 16. The packer 24, or another suitable sealing device, prevents the cement flowed from the inner string 30 to the branch wellbore 16 from flowing upwardly in the branch wellbore to its intersection with the parent wellbore 14. Among other benefits, this configuration prevents the cement from flowing into or accumulating about the whipstock 18.

[0033] For well control purposes, a valve 57 may be used to selectively prevent flow through the whipstock 18. The valve 57 is preferably pressure actuated using pressure applied to the interior of the whipstock 18 after the plug devices 36, 38, 40 are opened. Pressure actuated sliding sleeve valves, pressure actuated interval control valves, and other types of conventional valves may be used for the valve 57. Of course, the valve 57 may be actuated by a means other than pressure without departing from the principles of the invention.

[0034] Referring additionally now to FIG. 2, the method 10 is representatively illustrated after additional steps of the method have been performed. The cement flowed through the transition joint 28 has been allowed to harden. The plug devices 36, 38, 40 have been opened to thereby permit flow through the sidewall of the transition joint 28, and the valve 57 has been opened to permit flow through the whipstock 18, as indicated by arrows 58. The plug devices 36, 38, 40 and valve 57 are opened as described above.

[0035] Note that the flow 58 also passes through an internal passage 60 of the whipstock 18. Fluid communication is thus provided between the parent wellbore 14 above the wellbore intersection and the parent wellbore below the wellbore intersection. As described above, the plug devices 36, 38, 40 may be oriented so that the fluid flow 58 through the plug devices is in the same direction as flow through the passage 60.

[0036] Flow from the branch wellbore 16 (indicated by arrow 62) may commingle with the flow 58 from the lower parent wellbore 14, so that the flow into the upper parent wellbore (indicated by arrow 64) is from both the branch and lower parent wellbores. Of course, the well may be an injection well instead of a production well, in which case the above described flow directions may be reversed, and flow from or into each of the wellbores may be isolated from other wellbore fluid flows.

[0037] The plug device 36 is opened by conveying a cutting tool, such as a conventional clean-up tool used after cementing operations, or a drill, reamer, etc., into the transition joint 28 and cutting into the cap 42. Preferably, the cap 42 is completely removed, thereby completely opening the tubular body of the plug device 36 to flow therethrough. Note that, even though the plug device 36 is opened, it still isolates the annular space 34 from the interior and exterior of the transition joint 28.

[0038] The plug device 38 is opened by dissolving the plug 44 on the inner end of the plug device. This dissolving step may be performed, for example, by spotting an acid in the transition joint 28 for a time sufficient to dissolve the plug 44. A similar method may be used to dissolve the plug 46 in the tubular body of the plug device 40. Other methods of dissolving the plugs 44, 46 may be used, without departing from the principles of the invention.

[0039] Of course, a person skilled in the art would, upon a careful consideration of the above description of representative embodiments of the invention, readily appreciate that many modifications, additions, substitutions, deletions, and other changes may be made to these specific embodiments, and such changes are contemplated by the principles of the present invention. Accordingly, the foregoing detailed description is to be clearly understood as being given by way of illustration and example only, the spirit and scope of the present invention being limited solely by the appended claims and their equivalents.