Description:
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BACKGROUND
When a casing within a well bore has been lost or cut loose for any reason, a connection to the upper end of the casing is attempted. This type of connection is also used in the event the casing has stuck to adjust the vertical position of the top of the casing. Such connection is referred to herein as a casing patch. It is preferred that the casing patch be made to a hanger or other suitable equipment which can be supported within a wellhead housing and that the casing be held in tension during the making of the patch.
A particularly advantageous manner of providing such casing patch is to provide a cold forging tool which is positioned within the casing and a hanger having a gripping and sealing interior contour positioned around the casing near its upper end. U.S. patent application Ser. No. 044,409, filed Apr. 30, discloses a cold forging method, apparatus and tool therefor which can be used to make a casing patch.
Casing which is in a well bore as a "fish" can be engaged internally by a device commonly referred to as a spear and when the spear has engaged, tension can be exerted on the string in which the spear is engaged to exert a tension on the casing. One disadvantage which has been encountered with the use of spears to tension casing is that considerable radial loading may be necessary on the casing and to prevent slipping of the spear, the spear slips are highly loaded. Also, the tensioning can also increase the loading of the slips against the interior of the casing. Such high slip loading has caused excessive deformation of the casing in the past.
SUMMARY
The present invention relates to a method and an apparatus for making a casing patch while the casing is held under tension. The method includes the steps of lowering a casing patch tool to position the annular member to which the upper end of the casing is to be connected and a casing protection collar both in surrounding relationship to the upper end of the casing and with the cold forging tool and the tensioning spear within the casing, setting the spear within the casing at a level surrounded by the casing protection collar, pulling on the spear to tension the casing, and cold forgoing the casing into tight gripping and sealing engagement with the annular member. The apparatus includes the annular member to which the casing is to be connected, a guide sleeve on the lower end of the annular member sized to be lowered in the well bore and into surrounding relation to the upper end of the casing, a cold forging tool, a spear and a protection collar positioned within said annular member at the level of the spear so that it surrounds the casing to prevent excessive deformation on setting and tensioning by the spear. It is also a part of this invention to provide an improved method and apparatus to protect the casing from excessive deformation by surrounding its exterior in the area of spear engagement with a protection collar.
It is an object of the present invention to provide an improved method and apparatus for the installation of a casing patch which is done with the casing under tension and without excessive deformation to the casing.
Another object is to provide an improved method and apparatus for effecting a casing patch in which the unit is tensioned by a spear which engages within the upper end of the casing so that the casing below such spear engagement is under tension as it is cold forged into tight gripping and sealing engagement within an annular member surrounding the casing.
A further object is to provide an improved spear and method of tensioning a string which protects the string being engaged by the spear from excessive deformation by the spear slip loading and the tension loads.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other objects and advantages of the present invention are hereinafter set forth and explained with reference to the drawings wherein:
FIG. 1 is a detail sectional view of a well bore showing a casing in the lower portion thereof and an annular member with a protection collar supported within said annular member and a guide sleeve on lower end of the annular member being lowered within the well bore into surrounding relationship to the upper end of the casing fish.
FIG. 2 is a view similar to FIG. 1 but illustrates the position at which the annular member is supported for subsequent operations.
FIG. 3 is another similar view showing the cold forging tool and the spear after they have been lowered to a preselected position within the casing fish.
FIG. 4 is another similar view showing the setting of the spear within the upper end of the casing fish.
FIG. 5 is another similar view showing the tensioning of the casing fish by lifting of the string supporting the spear and forging tool.
FIG. 6 is another similar view illustrating the cold forging connection being made between the casing fish and the contour on the interior of the annular member.
FIG. 7 is another similar view showing the release of the cold forging tool from the interior of the casing fish.
FIG. 8 is another similar view illustrating the release of the spear.
FIG. 9 is another similar view illustrating a pressure testing tool positioned within the annular member and the casing to pressure test the cold forged joint between the two.
DESCRIPTION OF THE PREFERRED EMBODIMENT
As shown in FIG. 1, outer casing 10 is positioned within a well bore and inner casing fish 14 is positioned within outer casing 10. Annular member 16 having an internal contoured recess 18 has guide sleeve 20 secured to its lower end as by threads 22. The lower interior of guide sleeve 20 is tapered so that it will cause the upper end of inner casing fish 14 to move into the interior of guide sleeve 20. Protection collar 24 is positioned on upwardly facing shoulder 26 on the upper end of annular member 16 and within tubular connector 28 which is threaded onto the upper exterior of annular member 16. With the upper end of inner casing fish 14 within guide sleeve 20, guide sleeve 20, annular member 16 and protection collar 24 are lowered until the upper end of inner casing fish 14 is within the upper half of protection coolar 24. Connector 28, as shown in FIG. 2, is secured to the lower end of string 30 on which the outer assembly described is lowered.
With the outer assembly positioned as described above, the inner assembly is lowered through string 30 on drill pipe 32 to position spear 34 within the upper end of casing fish 14 and at a level at which casing fish 14 is surrounded by protection collar 24, forging tool 36 is within casing fish 14 below spear 34 and at least partially below the lower level of contoured recess 18 as shown in FIG. 3. Pump and instrument pod 38 is positioned above spear 34 on drill pipe 32. Tubing 40 connects from pod 38 through spear 34 into tool 36 to provide the pressure fluid for the actuation of tool 36. Tool 36 is preferred to be a tool such as is disclosed in the copending application Ser. No. 07,114,422, filed Oct. 28, . Spear 34 is any suitable available spear which includes other slips 42 and an inner mandrel 44 which moves axially of the slips 42 to wedge them outward into gripping engagement with the interior of the upper end of casing fish 14. As mentioned above, tool 36 is positioned below its desired position with respect to contour recess 18 by a distance which includes the anticipated elongation of the casing fish 14 and the distance the spear mandrel 44 is estimated to travel to properly and completely set slips 42.
FIG. 4 illustrates the relative position of the inner and outer assemblies after the spear mandrel 44 has been moved upwardly within slips 42 causing slips 42 to be moved outward into tight gripping engagement within the upper end of casing fish 14. It should be noted that tool 36 has been moved upwardly within annular member 16 the distance of the setting movement of spear mandrel 14 but tool 36 is still below the upper end of contoured recess 18. The gripping engagement of spear 34 into the interior of casing 14 causes casing 14 to be forced outward into engagement with protection collar 24. Collar 24 is sufficiently thick and strong so that further distortion of casing 14 responsive to the gripping forces of spear 34 is prevented.
FIG. 5 illustrates the positions of the components after spear 34 has been set and lifted by drill pipe 32 to effect the desired amount of tension in casing fish 14. This has caused casing fish 14 to elongate and inner assembly to be raised so that tool 36 is positioned at the desired level within annular member 16. In this position the forging of casing fish 14 is outward into internal contoured recess 18 of annular member 16. This forging step is illustrated in FIG. 6. When such forging is completed responsive to the delivery of fluid under pressure from pod 38 through tubing 40 into tool 36, the resilient packing is forced outward forcing the portion of casing 14 which it engages outward into tight sealing and gripping engagement with internal contoured recess 18.
With the completion of the forging step as described above, the pressure within tool 36 is relieved and its resilient packing relaxes back to its normal position immediately surrounding the body of tool 36. This position is shown in FIG. 7. Following the release of tool 36, spear 34 is released by lowering of drill pipe 32 to cause spear mandrel 44 to move out from under spear slips 42 and causing slips 42 to withdraw from engagement with casing 14. In this position, shown in FIG. 8, inner assembly is recovered from within outer causing 10 and pressure testing tool 46 is lowered on drill string 48 into the interior of annular member 16 and the interior of casing 14. In its set position as shown in FIG. 9, upper packing seal 50 is set within string 30 above connector 28 and above the upper end of of annular member 16. Lower packing seal 52 is set within casing 14 at a position below the portion of casing 14 which has been forged into engagement with contoured recess 18 within annular member 16. To test the sealing of the forged connection, pressure is delivered through drill string 48 and out its central opening 54. Since blind cap 56 is secured to the lower end of string 48, any loss of pressure notice at the surface in string 48 after it has been fully pressurized will indicated a leakage in the forged connection.
It should be noted that the use of the protection collar with the spear to protect the casing from excessive deformation responsive to the setting of the spear and its tension loading which increases the gripping loading on the casing may be used in application other than the method and apparatus for providing a casing patch.
There are several ways to repair the casing and to repair the seam or hole:
Squeeze Cement Slurry
When the pressure of the oil layer is not large, and the cracking and leakage are not serious, the cement slurry can be repaired. The technical method is as follows: firstly, the diameter of the well is 8 to 10 mm smaller than the inner diameter of the casing, and then a suspended occluder (the name of the tool is called bridge plug) at the appropriate position of the fracture, and the well bore below the breach is temporarily sealed off. Then, a certain amount of cement slurry is injected above the bridge plug to solidify into a cement plug. After the cement plug is solidified, the cement plug in the casing is drilled, and the quality of the cement seal is tested by pressure test, and the sealing is confirmed. After the quality is qualified, the suspended occluder (bridge plug) is drilled and sanded to the bottom of the well. The casing repaired by this method can generally withstand a pressure of 40 to 80 MPa, and the high-pressure construction of the well should be protected by a lower packer to avoid the high pressure.
Change the Casing
When the rupture position is in the upper part of the oil well, and the casing above the broken hole can be taken out by the buckle, the casing above the accident section can be all raised up by the reverse buckle method, and the new casing is re-inserted, and the buckle is tightened. The advantage of this method is to ensure the consistency of the inner diameter of the casing, and the downhole tool can be smoothly passed in the future operation; the disadvantage is that the casing thread of the downhole buckle is not as tight as the wellhead.
Subsidy Law
That is, a thin-walled pipe is attached to the inner wall of the bad casing for the purpose of repair. The principle of the process is: after a special high-pressure rubber cylinder is sleeved with a bellows (thin wall tube) to the damaged position of the well casing, the pressing force causes the rubber cylinder to expand and expand the bellows to make the bellows fit. The casing is damaged at the inner wall, and the sleeve is bonded to the bellows by the adhesive. After the adhesive is solidified, the drill is removed and the high pressure resistant rubber cylinder is taken out. This subsidy process is simple and safe to operate.
The wells broken by the casing were repaired in three cases. The first is broken but not misplaced; the second is broken but the misalignment is not serious; the third is broken and severely misaligned, and even the lower casing cannot be found.
In order to obtain the displacement after the casing is broken, the depth of the fault, the relative distance between the upper and lower sides of the fracture, and whether the fracture is deformed, etc., the situation can be clarified by using lead printing and instrument testing.
For casings that are not broken, they can be repaired by grouting; for casings that are broken but not dislocated, if the casing is allowed to be changed, the casing can be repaired; if the casing is not replaced, the casing can be used. The method of the device is repaired, that is, after the casing of the broken portion is milled and cut off, the upper and lower casings are clamped and pulled by the patching tool in the middle to ensure the normal production of the oil well.
Wells that are severely misaligned after breaking and cannot find the casing of the lower section can be treated by the sidetracking method. That is, the well bore at the breakage is cemented to death, and one well bore is drilled from the lower casing of the upper casing, and the casing is cemented and completed with a smaller casing than the original casing.
9 5/8"(244.48mm) Seamless oil Casing pipe
API-5CT Casing Pipe Steel grade: J55/K55/N80/L80/P110/C95/13Cr/28Cr
Threads: BTC, LTC, STC&#;PRMIUM CONNECTION
Length range: R1, R2, R3
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OD mm
Ib/ft
Grade
W. T
short
long
buttress
244.48(9 5/8" )
32.30
H
7.92
YES
36.00
H, J, K
8.94
YES
YES
YES
40.00
J, K, C, L, N
10.03
YES
YES
43.50
C, L, N, P
11.05
YES
YES
47.00
C, L, N, P, Q
11.99
YES
YES
53.50
C, L, N, P, Q
13.84
YES
YES
a: Buttress casing is available with regular, special clearance couplings or special clearance couplings with special bevel.
P= Plain end; S= Short round thread; L= Long round thread; B= Buttress thread.
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