AU7250200A

AU7250200A - Liner sliver retrieval method for multilateral wells

Info

Publication number: AU7250200A
Application number: AU72502/00A
Authority: AU
Inventors: Robbie B Colbert; John P Davis
Original assignee: Baker Hughes Inc
Current assignee: Baker Hughes Holdings LLC
Priority date: 1999-12-22
Filing date: 2000-12-22
Publication date: 2001-06-28
Also published as: NO20006549L; GB0031351D0; GB2357535A; CA2329429A1; NO20006549D0

Description

P/00/011 Regulation 3.2

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Invention Title: Liner sliver retrieval method for multilateral wells .The following statement is a full description of this invention, 'method of performing it known to us: *oo o *o *o o including the best Freehills Carter Smith BeadleMELC600372248.1 2 TITLE OF THE INVENTION Liner Sliver Retrieval Method for Multilateral Wells BACKGROUND OF THE INVENTION Field of the Invention This invention is in the field of cutting through a liner which has been installed in a lateral well bore, such as in an oil or gas well.

Background Art It is well known in the art to mill a window in the wall of a casing in a well bore, followed by the drilling of a lateral well bore through the window and installation of a liner in the lateral well bore. The upper end of the liner typically extends up into the main well bore a short distance. If access to the main well bore below the window is subsequently desired, it is necessary to cut through the upper end of the liner and "wash over", or mill down around, the whipstock which was used in milling out the window and drilling the lateral bore. This frees the upper end of the liner and the whipstock to be pulled from the main well bore. The "washover pipe" used in this operation is essentially a pipe larger in diameter than the liner and the whipstock, with an open lower end, and with milling inserts dressed around the lower end, often called a "rotary shoe". As this washover pipe is rotated 2 and forced downwardly, it basically cores out the main well bore, passing over the 0 upper end of the liner and the whipstock.

The main problem with this operation occurs when the rotary shoe on the lower end of the washover pipe penetrates the liner where the liner passes through the casing window, thereby separating the upper end of the liner from the laterally extending portion of the liner. This loose upper fragment of the liner, shaped like a wedge or spear, is free to move about, rotate, and drop downwardly, and in doing so, it often becomes wedged between the rotary shoe and the whipstock or the casing of the main well bore. This can render the rotary shoe ineffective, or at least severely inhibit its cutting action.

When this problem occurs, it is usually necessary to pull the washover pipe and rotary shoe from the well bore and run in a spear to retrieve the liner fragment.

Considering the cost of rig time, it would be very beneficial to eliminate this extra tripping of tools to retrieve the loose liner fragment.

BRIEF SUMMARY OF THE INVENTION The present invention is a method and apparatus for cutting through the upper end of a liner in a lateral well bore, washing over the whipstock, and retrieving the liner fragment, all in one trip of a tool. Both mechanically and hydraulically actuated embodiments of the apparatus are provided. In either case, the apparatus includes a washover pipe, a rotary shoe on the lower end of the washover pipe, and a fishing spear within the washover pipe. In both embodiments, the apparatus is lowered into the main well bore, the rotary shoe cuts through the liner, the spear captures the liner fragment and lifts it away from the rotary shoe, and the washover operation continues.

In the mechanical embodiment, the spear is up within the washover pipe, above the S: rotary shoe. The rotary shoe first cuts through the liner, then the spear is lowered i 20 within the washover pipe to grab the upper end of the liner fragment and pull it up within the washover pipe, followed by continuation of the washover operation.

the hydraulic embodiment, the spear is inside the washover pipe, but extending from the lower end thereof, below the rotary shoe. The spear first engages the upper end of the liner. Then, the washover pipe is freed to rotate separately from the spear. As the washover pipe and rotary shoe rotate and move downwardly, the rotary shoe cuts through the liner. During this time, drilling fluid is being pumped .I down through the work string and the washover assembly, creating a backpressure below the spear. When the liner fragment is freed from the liner, this backpressure exerts an upward force on the spear, driving the spear and the liner fragment upwardly into the washover pipe.

The novel features of this invention, as well as the invention itself, will be best understood from the attached drawings, taken along with the following description, in which similar reference characters refer to similar parts, and in which: BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS Figure IA is a sectional view of a J-housing used in the mechanical embodiment of the apparatus of the present invention; Figure 1Bsis a partial sectional view of a J-mandrel used in the mechanical embodiment of the apparatus of the present invention; Figure 1C is a sectional view of a spear used in the mechanical embodiment of the apparatus of the present invention; Figure 2 is a sectional view of the mechanical embodiment of the apparatus of the present invention, being lowered toward the upper end of the liner; Figure 3 is a sectional view of the mechanical embodiment of the apparatus of the present invention, at the point where the liner fragment has been milled through; Figure 4 is a sectional view of the mechanical embodiment of the apparatus of the present invention, at the point where the spear has been lowered to engage the liner fragment; Figure 5 is a sectional view of the mechanical embodiment of the apparatus of 20 the present invention, showing the spear and liner fragment within the washover pipe to allow completion of the washover operation; S" Figure 6 is a sectional view of the hydraulic embodiment of the apparatus of the present invention, showing the spear engaging the upper end of the liner fragment; ooo.oi •"Figure 7 is a sectional view of the hydraulic embodiment of the apparatus of 25 the present invention, showing the rotary shoe cutting through the liner; 0oV0 Figure 8 is a sectional view of the hydraulic embodiment of the apparatus of the present invention, showing the liner fragment being pulled upwardly after being cut free; and Figure 9 is a sectional view of the hydraulic embodiment of the apparatus of the present invention, showing the liner fragment captured within the washover pipe.

DETAILED DESCRIPTION OF THE INVENTION As shown in Figure 1A, in the mechanical embodiment, the J-housing 12 has a plurality of stabilizers 34 at its upper end, a junk protection sleeve 36, and a plurality of inwardly projecting lugs 38 on the interior of a control bushing 42. Threads 43 on the lower end of the control bushing 42 allow connection of the washover pipe to the J-housing. As shown in Figure 1B, the J-mandrel 14 has a J-groove 44 on its exterior surface for engaging the lugs 38 inside the J-housing 12. Shear pins 40 can be used to releasably capturelthe J-mandrel 14 within the J-housing 12. Upper threads 46 at the upper end of the J-mandrel 14 allow connection of the J-mandrel 14 to the lower end of a workstring. Lower threads 48 at the lower end of the J-mandrel 14 allow connection of the upper end of the spear 16 to the lower end of the J-mandrel 14. As shown in Figure 1C, the spear 16 has gripping segments 50 pinned to the spear 16 in the release position by a shear pin 52. When the shear pin 52 is sheared, the force cone 54 can be pulled upwardly to cause the gripping segments 50 to engage the tubular element being speared.

As shown in Figure 2, in the run-in position, the apparatus 10 has the lugs 38 engaged in the J-groove 44, and the spear 16 is held in the upper position within the washover pipe 18 above the rotary shoe 28. A window 20 is shown in the main bore casing 26, with the liner 22 passing through the window 20 into the lateral well bore.

*i 20 The apparatus 10 is being lowered toward the upper end 24 of the liner 22. Once the rotary shoe 28 contacts the upper end 24 of the liner 22, rotation of the workstring rotates the J-mandrel 14, which, by means of engagement of the lugs 38 with the Jgroove 44, rotates the J-housing 12, the washover pipe 18, and the rotary shoe 28.

This causes the rotary shoe 28 to cut through the liner 22 and wash over the upper end of the whipstock 32, freeing the liner fragment 30, at the stage shown in Figure 3.

*oo At this point, the workstring is slacked off to shear the J-housing shear pins o 40, allowing the J-mandrel 14 to be rotated to align the open channels of the J-grooves 44 with the lugs 38. Further lowering of the workstring causes the spear 16 to enter the upper end 24 of the liner fragment 30. The spear pins 52 are sheared to allow the force cone 54 to be pulled upwardly, causing the spear 16 to engage the liner fragment as shown in Figure 4. Further raising of the workstring lifts the liner fragment and the spear 16 until the J-groove 44 is again engaged with the lugs 38, as shown in Figure 5. This holds the liner fragment 30 in a raised position within the washover assembly, allowing the washover pipe 18 to again be rotated and lowered over the whipstock 32.

The hydraulically actuated apparatus 60 of the present invention is shown in Figures 6 through 9. A washover pipe 62 is connected at its upper end to a packoff, catch, and drain sub 64, referred to hereinafter as the catch sub 64. A rotary shoe 66 is mounted to the lower end of the washover pipe 62. Drain holes 68 drain the inside of the catch sub 64 too the annulus. Shear pins 70 releasably attach the catch sub 64 to the upper end of a length of flush joint pipe 74. Packing 72 seals between the flush joint pipe 74 and the catch sub 64. A grappling sub 76, which is engageable with the catch sub 64, is mounted to the lower end of the flush joint pipe 74. A packoff sub 78 is attached below the grappling sub 76, with a packoff 80 and a stabilizer 82 sealing and centering the packoff sub 78 in the washover pipe 62. A spear 86 is mounted below the packoff sub 78, with a releasable connection, such as with a J-joint 84, or another suitable releasable device. A stop ring 88 can be provided at the top of the spear 86.

As shown in Figure 6, the apparatus 60 has been lowered until the spear 86 is fully inserted into the upper end 24 of the liner 22, with the stop ring 88 at the upper end 24. The spear 86 is then set in the liner 22. The pins 70 are then sheared, and rotation of the washover pipe 62 is started. This causes the rotary shoe 66 to cut through the liner 22, as shown in Figure 7. During this cutting process, the spear 86 0: and the packoff sub 78 exert upward tension on the upper end 24 of the liner 22, :0.

because of hydraulic pressure below the packoff sub 78, as a result of the pumping of drilling fluid down through the spear 86. When the rotary shoe 66 has cut the liner 9 fragment 30 free, as shown in Figure 8, the hydraulic pressure forces the spear 86, the packoff sub 78, the grappling sub 76, and the liner fragment 30 upwardly through the washover pipe 62. As the spear 86, the packoff sub 78, the grappling sub 76, and the S°liner fragment 30 move upwardly, pressure above the packoff sub 78 is bled off to the annulus via the drain holes 68.

As shown in Figure 9, when the grappling sub 76 reaches and engages the catch sub 64, the liner fragment 30 is held at a sufficient height above the rotary shoe 66 to allow completion of the washover operation.

While the particular invention as herein shown and disclosed in detail is fully capable of obtaining the objects and providing the advantages hereinbefore stated, it is to be understood that this disclosure is merely illustrative of the presently preferred embodiments of the invention and that no limitations are intended other than as described in the appended claims.

It will be understood that the term "comprising" or its grammatical variants as used herein is equivalent to the term "includes" and is not to be taken as excluding the presence of other elements or features.

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