A method and tool for free section casing breakback

Abstract

This invention belongs to the field of oilfield downhole operation technology, and particularly relates to a method and tool for retrieving free-segment casing fractures. The method is based on this free-segment casing fracture retrieval tool, which includes a guide rail upper connector; a suspension piston movably connected to the guide rail upper connector; an outer cylinder connected to the guide rail upper connector; a suspension expanding cone disposed between the outer cylinder and the suspension piston; a guide shell connected to the outer cylinder; and at least one chamfered expanding plate movably connected to the guide shell and the suspension expanding cone. The free-segment casing fracture retrieval method and tool of this invention can solve the problem that conventional tools cannot reach the fracture surface after casing is cut and deflected, effectively improving the success rate of complex casing retrieval and providing technical support for the efficient management of shallow casing-damaged wells in oilfields.

Description

Technical Field

[0001] This invention belongs to the field of oilfield downhole operation technology, and relates to a tool and method for retrieving a broken section of free casing, particularly a method and tool for retrieving a broken section of free casing used in oil and water well workover operations. Background Technology

[0002] During oil and water well production, fluid corrosion, surface subsidence, and other factors can cause leakage or deformation of the casing in shallow oil layers. The most thorough repair method is casing replacement, which involves removing the damaged section and the upper portion of the oil layer casing and replacing it with a new casing. In some wells, due to severe casing deformation and large horizontal wellbore displacement, the casing may wear off before reaching the change point during milling, resulting in casing breakage. Furthermore, after breakage, the cut surface is easily misaligned, making recovery difficult. Figure 1 , Figure 2 As shown.

[0003] In other words, if the casing is broken or misaligned when using conventional milling technology, the milling and guiding tools will have difficulty touching the broken lower casing due to factors such as the rigidity of the tubing string and wellbore guidance, and will be unable to find the original casing passage.

[0004] Therefore, existing technologies still need improvement. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by providing a method and tool for recovering the broken section of a free-segment casing. After the casing string is lowered below the outer casing, multiple recovery mechanisms are used to locally damage the side of the biased casing. The casing is then recovered using radial force, solving the problem of the inability to locate the broken section of the free-segment casing and ensuring the successful completion of the casing replacement operation.

[0006] According to one aspect of the present invention, a method for recovering a free section of a casing fracture is provided, wherein the method is based on a free section casing fracture recovery tool, wherein the free section casing fracture recovery tool includes a guide rail upper connector; a suspension piston movably connected to the guide rail upper connector; an outer cylinder connected to the guide rail upper connector; a suspension expanding cone disposed between the outer cylinder and the suspension piston; a guide housing connected to the outer cylinder; and at least one chamfering expanding plate movably connected to the guide housing and the suspension expanding cone, and the method includes the following steps:

[0007] a. Lower the tubing string with the free section casing breakage retraction tool at the bottom below the surface casing until above the breakage position of the oil layer casing. Under hydraulic pressure, move the chamfered expansion plate radially so that the maximum outer diameter of the free section casing breakage retraction tool exceeds the inner diameter of the surface casing.

[0008] b. Rotate the tubing column so that the bottom of the chamfered expansion plate cuts the side of the offset sleeve to locally destroy the contact part through milling; continue to lower the tubing column, and while milling, use the radial force generated to draw the sleeve body towards the center through cutting;

[0009] c. Lift the tubing string to retract the chamfered expansion plate, so that the maximum outer diameter of the free section casing breakage retraction tool is reduced to less than the inner diameter of the surface casing, and continue to lift and pull out the tool;

[0010] d. Use a milling tool with a lower outer diameter smaller than the inner diameter of the outer sleeve to replace the sleeve.

[0011] In an embodiment of the present invention, the maximum outer diameter of the free section sleeve breakage recovery tool satisfies the following formula:

[0012] When there is no deformation in the surface sleeve: W≤Dsc-10mm;

[0013] When the surface sleeve is deformed: W≤Dsc-20mm

[0014] Where Dsc is the inner diameter of the surface casing; W is the maximum outer diameter of the free section casing breakage retrieval tool.

[0015] In an embodiment of the present invention, step a, the radial movement of the chamfered expansion plate under hydraulic action includes: by placing a ball on the top ball seat of the suspension piston, the suspension piston is pushed downward, thereby pushing the suspension expansion cone downward, so that their contact surface enters the cyclic position, and at the same time the suspension expansion cone pushes the chamfered expansion plate through its second guide rail, so that it moves radially along the third guide rail of the guide housing.

[0016] In an embodiment of the present invention, the bottom of the chamfered expansion piece is provided with an inward bevel, and the bevel is covered with a high-strength alloy.

[0017] In an embodiment of the present invention, step b, which involves cutting the side of the bias sleeve at the bottom of the chamfered expansion plate to locally damage the contact portion by milling, includes: making the side of the bias sleeve at the bottom of the chamfered expansion plate contacted by the high-hardness alloy, and creating a notch on the side of the sleeve by milling to locally damage the contact portion.

[0018] In an embodiment of the present invention, in step b, three chamfered expansion plates are arranged around the circumference of the tubular column.

[0019] In an embodiment of the present invention, step c, the retraction of the chamfered expansion plate includes: causing the connector on the guide rail to drive the suspension piston, which is at the end of its stroke, to move upward; the relative position of the suspension piston and the suspension expansion cone enters the locked position; the suspension expansion cone moves upward; the chamfered expansion plate is squeezed by the upper unexpanded stratum, thus achieving retraction.

[0020] In an embodiment of the present invention, the contact surface between the suspension piston and the suspension expansion cone is provided with a conversion groove, the conversion groove including a first conversion groove and a second conversion groove, wherein the first conversion groove provides a mud circulation channel and the second conversion groove provides an upward hook function.

[0021] In an embodiment of the present invention, the locking position is the second conversion slot.

[0022] According to another aspect of the present invention, a free-segment sleeve breakage retraction tool is provided, comprising: a guide rail upper connector; a suspension piston movably connected to the guide rail upper connector; an outer cylinder connected to the guide rail upper connector; a suspension expansion cone disposed between the outer cylinder and the suspension piston; a guide housing connected to the outer cylinder; and at least one chamfered expansion piece movably connected to the guide housing and the suspension expansion cone.

[0023] In an embodiment of the present invention, the contact surface between the suspension piston and the suspension expansion cone is provided with a conversion groove, the conversion groove including a first conversion groove and a second conversion groove, wherein the first conversion groove provides a mud circulation channel and the second conversion groove provides an upward hook function.

[0024] In an embodiment of the invention, a plurality of chamfered expansion plates, which are movably connected to the guide housing and the suspension expansion cone, are arranged circumferentially.

[0025] In an embodiment of the present invention, the bottom of the chamfered expansion piece is provided with an inward bevel, and the bevel is covered with a high-strength alloy.

[0026] In an embodiment of the present invention, the outer wall of the guide rail connector is provided with a step, and the outer cylinder is connected to the guide rail connector through the step.

[0027] In an embodiment of the present invention, a first guide rail is provided on the inner side of the guide rail connector. The first guide rail connects to a portion of the suspension piston and allows the portion to move axially along the first guide rail.

[0028] In an embodiment of the present invention, the outer cylinder is a sealed outer cylinder, and the outer wall of the outer cylinder is connected to the guide shell by threads.

[0029] In an embodiment of the present invention, the suspension expansion cone is sleeved between the suspension piston and the outer cylinder, and sealing mechanisms are provided on the inner and outer sides of the upper step of the suspension expansion cone, and a conical surface is provided on the lower part of the suspension expansion cone.

[0030] In an embodiment of the present invention, the conical surface includes a second guide rail, which connects to a first portion of the chamfered and expanded diameter plate and allows the first portion to move along the second guide rail. The first portion and the second guide rail are installed by keyway engagement.

[0031] In an embodiment of the present invention, the upper part of the guide housing is sealed to the outer cylinder, and a third guide rail is provided at the bottom of the guide housing. The third guide rail connects to the second part of the chamfered and expanded diameter plate and allows the second part to move radially outward along the third guide rail. The second part and the third guide rail are installed by keyway engagement.

[0032] This invention solves the problem that conventional tools cannot reach the break point after the casing is cut off, effectively improving the success rate of complex casing removal and providing technical support for the efficient treatment of shallow casing-damaged wells in oilfields. Attached Figure Description

[0033] Figure 1 A schematic diagram of milling and offset sleeve is shown;

[0034] Figure 2 A schematic diagram of the horizontal displacement of the wellbore is shown;

[0035] Figure 3 A cross-sectional schematic diagram of a free-segment casing breakage recovery tool according to an embodiment of the present invention is shown;

[0036] Figure 4 A bottom view of a free-segment casing breakage recovery tool according to an embodiment of the present invention is shown;

[0037] Figure 5 A schematic flowchart of a method for retrieving a free section of the casing fracture according to an embodiment of the present invention is shown. Detailed Implementation

[0038] It should be understood that the embodiments of the invention shown in the exemplary embodiments are merely illustrative. Although only a few embodiments have been described in detail in this invention, those skilled in the art will readily recognize that various modifications are possible without substantially departing from the teachings of the invention. Accordingly, all such modifications should be included within the scope of the invention. Other substitutions, modifications, variations, and deletions can be made to the design, operating conditions, and parameters of the following exemplary embodiments without departing from the spirit of the invention.

[0039] According to one aspect of the present invention, a tool for retrieving a broken section of a free sleeve is provided, such as... Figure 3As shown, it includes: a guide rail upper connector 1; a suspension piston 2 movably connected to the guide rail upper connector 1; an outer cylinder 3 connected to the guide rail upper connector 1; a suspension expansion cone 4 disposed between the outer cylinder 3 and the suspension piston 2; a guide housing 5 connected to the outer cylinder 3; and at least one chamfered expansion piece 6 movably connected to the guide housing 5 and the suspension expansion cone 4. Figure 4 As shown, the tool for retrieving the free section of the casing fracture can be generally cylindrical.

[0040] In an embodiment of the present invention, the outer wall of the guide rail connector 1 is provided with a step 11, and the outer cylinder 3 has a shape adapted to the step 11 and can be connected to the guide rail connector 1 through the step 11. In one embodiment, an external thread may be provided on the step 11, and an internal thread may be provided inside the outer cylinder 3, so the outer cylinder 3 and the guide rail connector 1 can be connected by threads. A first guide rail 12 is provided on the inner side of the guide rail connector 1. The first guide rail 12 connects to a part of the suspension piston 2 and allows this part to move axially along the first guide rail 12. In one embodiment, the first guide rail 12 is provided at the bottom of the guide rail connector 1 and forms an axial movement engagement with the key on the upper part of the suspension piston 2. It should be understood that the upper, bottom, or lower part mentioned here and in other parts is with reference to the direction of the free section casing fracture retrieval tool entering the well, for example in Figure 3 In the diagram, the left side represents the upper part of the free-segment casing fracture retrieval tool, and the right side represents the bottom or lower part of the free-segment casing fracture retrieval tool; that is, the bottom or lower part is lowered into the well before the upper part. Furthermore, the axial and radial directions mentioned here and elsewhere are referenced to the axial and radial directions of the free-segment casing fracture retrieval tool.

[0041] In an embodiment of the present invention, the outer cylinder 3 is a sealed outer cylinder, and the outer wall of the outer cylinder 3 is connected to the guide shell 5 by threads, thereby facilitating installation and disassembly.

[0042] In an embodiment of the present invention, the suspension expansion cone 4 is sleeved between the suspension piston 2 and the outer cylinder 3, and the upper step of the suspension expansion cone 4 is provided with sealing mechanisms (such as sealing strips, sealing rings or sealing with sealant) on the inner and outer sides.

[0043] In an embodiment of the invention, a conical surface 41 is provided at the lower part of the suspended expanding cone 4. A second guide rail 42 corresponding to the chamfered expanding piece 6 is provided on the conical surface 41, and its direction is inclined downward. The second guide rail 42 connects to the first part 61 of the chamfered expanding piece 6 and allows the first part 61 to move along the second guide rail 42. The first part 61 and the second guide rail 42 are installed by keyway engagement. The bottom of the chamfered expanding piece 6 is provided with an inward bevel (not shown in the figure), which is covered with a high-strength alloy.

[0044] In an embodiment of the present invention, the upper part of the guide housing 5 is sealed to the outer cylinder 3, and the bottom of the guide housing 5 is provided with a third guide rail 51. The third guide rail 51 is connected to the second part 62 of the chamfered expansion plate 6 and allows the second part 62 to move radially outward along the third guide rail 51. The second part 62 and the third guide rail 51 are installed by keyway cooperation.

[0045] In an embodiment of the present invention, the contact surface between the suspension piston 2 and the suspension expansion cone 4 is provided with a conversion groove, which includes a first conversion groove and a second conversion groove, wherein the first conversion groove provides a mud circulation channel and the second conversion groove provides an upward hook function.

[0046] In embodiments of the present invention, the chamfered expanding plates 6 can constitute a receiving mechanism, and multiple chamfered expanding plates 6 movably connected to the guide housing 5 and the suspension expanding cone 4 are arranged circumferentially. In one embodiment, three chamfered expanding plates 6 can be provided to form three sets of receiving mechanisms, such as... Figure 4 As shown.

[0047] In an embodiment of the invention, a ball seat is provided on the top of the suspension piston 2, which can receive and accommodate a ball for applying hydraulic pressure.

[0048] The free-segment sleeve breakage retraction tool of the present invention can push the suspension piston 2 and the suspension expansion cone 4 downward under hydraulic action, so that their contact surfaces enter the circulation position. At the same time, the expansion cone pushes the chamfer expansion plate 6 through the axial guide rail, so that it moves along the radial guide rail of the fixed guide shell 5, so that the maximum outer diameter of the bottom inner chamfer retraction mechanism exceeds the inner diameter of the surface sleeve, thereby locally damaging the biased sleeve and retracting it towards the center.

[0049] According to another aspect of the present invention, a method for recovering the broken section of a free sleeve is provided, such as... Figure 5 The process includes the following steps:

[0050] a. Lower the tubing string with the free section casing fracture recovery tool at the bottom below the surface casing until above the fracture position of the oil layer casing. Under hydraulic pressure, move the chamfered expansion plate radially so that the maximum outer diameter of the free section casing fracture recovery tool exceeds the inner diameter of the surface casing. The free section casing fracture recovery tool can be the free section casing fracture recovery tool mentioned in the previous embodiment.

[0051] b. Rotate the tubing column so that the bottom of the chamfered expansion plate cuts the side of the offset sleeve to locally destroy the contact part through milling; continue to lower the tubing column, and while milling, use the radial force generated to draw the sleeve body towards the center through cutting;

[0052] c. Lift the tubing string to retract the chamfered expansion plate, so that the maximum outer diameter of the free section casing breakage retraction tool is reduced to less than the inner diameter of the surface casing, and continue to lift and pull out the tool;

[0053] d. Use a milling tool with a lower outer diameter smaller than the inner diameter of the outer sleeve to replace the sleeve.

[0054] In an embodiment of the present invention, the maximum outer diameter of the free section sleeve breakage retrieval tool satisfies the following formula:

[0055] When there is no deformation in the surface sleeve: W≤Dsc-10mm;

[0056] When the surface sleeve is deformed: W≤Dsc-20mm

[0057] Where Dsc is the inner diameter of the surface casing in mm; W is the maximum outer diameter of the free section casing breakage retrieval tool in mm.

[0058] In an embodiment of the present invention, step a, the radial movement of the chamfered expansion plate 6 under hydraulic pressure, includes: by placing a ball seat on the top ball seat of the suspension piston 2, the suspension piston 2 is pushed downward, thereby pushing the suspension expansion cone 4 downward, so that their contact surface enters the circulation position. At the same time, the suspension expansion cone 4 pushes the chamfered expansion plate 6 through its second guide rail 42, so that it moves radially along the third guide rail 51 of the guide housing 5. In one embodiment, step a specifically includes: lowering the free section casing breakage retrieval tool below the surface casing, into the formation (free section without casing and cementing), and continuing to lower it above the breakage position of the oil layer casing; by hydraulic pressure, the suspension piston 2 and the suspension expansion cone 4 are pushed downward in sequence, so that their contact surface enters the circulation position. At the same time, the suspension expansion cone 4 pushes the chamfered expansion plate 6 through the axial guide rail, so that it moves along the radial guide rail of the fixed guide housing 5, so that the maximum outer diameter of the bottom inner chamfering retrieval mechanism exceeds the inner diameter of the surface casing.

[0059] In an embodiment of the present invention, step b, which involves cutting the side of the bias sleeve at the bottom of the chamfered expanding plate 6 to partially damage the contact portion through milling, includes: making the side of the bias sleeve contacted by the high-hardness alloy at the bottom of the chamfered expanding plate 6, and creating a notch on the side of the sleeve through milling to partially damage the contact portion. In one embodiment, step b specifically includes: rotating the tubing column, making the side of the bias sleeve contacted by the high-hardness alloy at the bottom of the chamfered expanding plate 6, and partially damaging the contact portion through milling; continuing to lower the tubing column, and the inner chamfering and retracting mechanism at the bottom generating a radial force during milling, causing the sleeve body to be retracted towards the center through cutting.

[0060] In an embodiment of the present invention, in step b, a plurality of chamfered expansion plates 6 are arranged around the circumference of the tubing. In one embodiment, the retracting mechanism can be modularized, with three retracting mechanisms arranged along the circumference.

[0061] In an embodiment of the present invention, step c, retrieving the chamfered expanding plate 6, includes: the upper connector 1 on the guide rail driving the suspension piston 2, which is at the end of its stroke, upwards; the relative position of the suspension piston 2 and the suspension expanding cone 4 enters the locked position; the suspension expanding cone 4 moves upwards; the chamfered expanding plate 6 is squeezed by the upper unexpanded stratum, thus achieving retrieval. In one embodiment, step c specifically includes: lifting the tubing string; the suspension piston 2 is at the end of its stroke; the upper connector 1 on the guide rail driving the suspension piston 2 upwards; the relative position of the suspension piston 2 and the suspension expanding cone 4 enters the locked position; the suspension expanding cone 4 moves upwards; the chamfered expanding plate 6 is squeezed by the upper unexpanded stratum, thus achieving retrieval; the maximum outer diameter of the tool is reduced to less than the inner diameter of the surface casing; the tool is then lifted out.

[0062] In an embodiment of the present invention, step d specifically includes: using a milling tool with an outer diameter smaller than the inner diameter of the surface sleeve to mill the centered sleeve break, and then inserting it into the milling cylinder; using a grinding milling tool to trim the sleeve break until the tracer string can be inserted; removing the sleeve and inserting a new sleeve for reconnection.

[0063] The free-segment casing breakage retrieval tool and method described in this invention can effectively solve the problem that conventional tools cannot reach the breakage after the casing is cut off, effectively improving the success rate of complex casing removal and providing technical support for the efficient treatment of shallow casing damage wells in oilfields.

[0064] The present invention is further illustrated below through specific embodiments:

[0065] The surface casing has an inner diameter of 320 mm and a depth of 100 m. The oil layer casing has an outer diameter of 139.7 mm. The oil layer casing was severely twisted and deformed near a depth of 160 m and broke during the milling process. It was then offset to one side, and the tubing string could not reach the casing.

[0066] This invention provides a method and tool for recovering a broken section of a free-segment sleeve:

[0067] (1) The sleeve is not deformed, and the maximum outer diameter of the free section sleeve breakage guide tool is 300mm.

[0068] (2) A milling or grinding shoe with an outer diameter of 300mm is used to treat the well to a depth of 158m. A free section casing breakage retrieval tool is installed at the bottom of the drill pipe. The guide housing 5 of the tool is equipped with 3 sets of retrieval mechanisms along the circumference. When the well reaches a depth of 156m, the ball is placed on the ball seat at the top of the suspension piston 2, and the suspension piston 2 is pushed down by pressure. The suspension expanding cone 4 continues to move down. During the descent, the contact surface of the two mechanisms enters the circulation position. At the same time, the suspension expanding cone 4 pushes the chamfered expanding plate 6 through the axial guide rail, so that it moves along the radial guide rail of the fixed guide housing 5. After expansion, the outer diameter of the tool is 340mm.

[0069] (3) Rotate the tubing string, and the free section of the casing is cut by the cutting tool. Continue to lower it. The high hardness alloy at the bottom of the chamfered expansion plate contacts the side of the biased casing. A notch is created on the side of the casing by milling. Continue to lower it for milling. The inner chamfering and milling mechanism at the bottom generates a radial force while milling, causing the casing body to be drawn towards the center through cutting. The casing is then processed downwards by 1m.

[0070] (4) Lift the tubing string. The suspension piston 2 is at the end of its stroke. The upper connector 1 of the guide rail drives the suspension piston 2 to move upward. The relative position of the suspension piston 2 and the suspension expansion cone 4 enters the second conversion groove, hooking the suspension expansion cone 4 to move upward. The chamfered expansion plate 6 is squeezed by the upper unexpanded stratum to achieve recovery, reducing the maximum outer diameter of the tool to within 320mm. Continue to lift the tool out.

[0071] (5) Use a 300mm outer diameter milling tool to mill the broken end of the casing that has been centered and put it into the milling sleeve. Place the drill rod with a flat-bottomed grinding shoe inside the milling sleeve and trim the broken end of the casing until the tracer string can be lowered. Remove the casing and lower a new D139.7mm casing for reconnection.

[0072] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the present invention. Any modifications or equivalent substitutions made to the present invention without departing from the spirit and scope thereof should be covered within the protection scope of the claims of the present invention.

Claims

1. A method for recovering a broken section of a free-segment casing, characterized in that, The method is based on a free-segment casing break retraction tool, wherein the free-segment casing break retraction tool includes a guide rail upper connector; a suspension piston movably connected to the guide rail upper connector; an outer cylinder connected to the guide rail upper connector; a suspension expanding cone disposed between the outer cylinder and the suspension piston; a guide housing connected to the outer cylinder; and at least one chamfering expanding plate movably connected to the guide housing and the suspension expanding cone, and the method includes the following steps: a. Lower the tubing string with the free section casing breakage retraction tool at the bottom below the surface casing until above the breakage position of the oil layer casing. Under hydraulic pressure, move the chamfered expansion plate radially so that the maximum outer diameter of the free section casing breakage retraction tool exceeds the inner diameter of the surface casing. The radial movement of the chamfered expansion plate under hydraulic pressure includes: pressing and pushing the suspension piston downward by placing a ball on the top ball seat of the suspension piston, thereby pushing the suspension expansion cone downward so that their contact surface enters the circulation position. At the same time, the suspension expansion cone pushes the chamfered expansion plate through the second guide rail of the suspension expansion cone, so that the chamfered expansion plate moves radially along the third guide rail of the guide housing. b. Rotate the tubing column so that the bottom of the chamfered expansion plate cuts the side of the offset sleeve to locally destroy the contact part through milling; continue to lower the tubing column, and while milling, use the radial force generated to draw the sleeve body towards the center through cutting; c. Lift the tubing string to retract the chamfered expansion plate, so that the maximum outer diameter of the free section casing breakage retraction tool is reduced to less than the inner diameter of the surface casing, and continue to lift and pull out the tool; d. Use a milling tool with a lower outer diameter smaller than the inner diameter of the outer sleeve to replace the sleeve.

2. The method according to claim 1, characterized in that, The bottom of the chamfered and expanded plate is provided with an inward bevel, and the bevel is covered with a high-strength alloy.

3. The method according to claim 2, characterized in that, In step b, the step of cutting the side of the bias sleeve at the bottom of the chamfered expansion plate to locally damage the contact portion by milling includes: making the side of the bias sleeve with a high-hardness alloy at the bottom of the chamfered expansion plate, and creating a notch on the side of the sleeve by milling to locally damage the contact portion.

4. The method according to claim 1, characterized in that, In step c, the retraction of the chamfered expansion plate includes: causing the connector on the guide rail to drive the suspension piston, which is at the end of its stroke, to move upward; the relative position of the suspension piston and the suspension expansion cone enters the locked position; the suspension expansion cone moves upward; the chamfered expansion plate is squeezed by the upper unexpanded stratum, thus achieving retraction.

5. The method according to claim 4, characterized in that, The contact surface between the suspension piston and the suspension expansion cone is provided with a conversion groove, which includes a first conversion groove and a second conversion groove. The first conversion groove provides a mud circulation channel, and the second conversion groove provides an upward hook function.

6. The method according to claim 5, characterized in that, The locking position is the second conversion slot.

7. The method according to claim 1, characterized in that, The plurality of chamfered expanding plates, which are movably connected to the guide housing and the suspension expanding cone, are arranged circumferentially.

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