Expansion pipe bottom plug, expansion pipe and fishing method for fishing the expansion pipe bottom plug

Abstract

The present invention provides an expansion pipe bottom plug, an expansion pipe and a fishing method for fishing the expansion pipe bottom plug. Among them, the expansion pipe bottom plug includes: a support shaft, the bottom end of the support shaft is a plugging end; a telescopic structure, arranged on the support shaft, the telescopic structure has a recovery position and an extended position that expands outwards, and the telescopic structure can move from the extended position to the recovery position under the action of an external force. Applying the technical solution of the present invention can effectively solve the problem of affecting the production of the pay zone caused by the need to damage the expansion pipe bottom plug when restoring the wellbore passage in the prior art.

Description

Technical Field

[0001] The present invention relates to the field of oil extraction, and more particularly, to an expandable pipe bottom plug, an expandable pipe, and a method for fishing the expandable pipe bottom plug. Background Art

[0002] In some production wells with a long oil production time, the casing often has leaks, damages, etc. due to long-term corrosion by various substances underground. This causes formation fluids to enter the wellbore, thereby affecting the productivity of the well. At this time, it is necessary to use expandable pipe technology to repair the damaged casing.

[0003] Since the repair position is generally above the pay zone, how to protect the pay zone and restore production after construction is a major problem. In the original expandable pipe construction string, the lower part is an aluminum alloy bottom plug. After the expandable pipe expands, in order to restore the wellbore passage, it is necessary to drill off the lower aluminum alloy bottom plug. During the drilling process, some remaining bottom plug fragments will fall into the pay zone position, which may affect the production of the pay zone. Summary of the Invention

[0004] The main object of the present invention is to provide an expandable pipe bottom plug, an expandable pipe, and a method for fishing the expandable pipe bottom plug, so as to solve the problem of affecting the production of the pay zone caused by the need to destroy the expandable pipe bottom plug when restoring the wellbore passage in the prior art.

[0005] To achieve the above object, according to one aspect of the present invention, there is provided an expandable pipe bottom plug, including: a support shaft, the bottom end of the support shaft being a sealing end; a telescopic structure disposed on the support shaft, the telescopic structure having a retracted position and an extended position where it expands outward, and the telescopic structure being capable of moving from the extended position to the retracted position under the action of an external force.

[0006] Further, the telescopic structure includes telescopic blocks that move radially along the support shaft, and the expandable pipe bottom plug further includes: an elastic member disposed between the telescopic blocks and the support shaft.

[0007] Further, the support shaft includes a necking section, the outer wall of the necking section includes an inclined surface that gradually contracts in the direction from the top end to the bottom end of the support shaft, the elastic member is located below the telescopic blocks to support the telescopic blocks, and the telescopic blocks are capable of sliding along the inclined surface under the action of an external force to switch between the extended position and the retracted position.

[0008] Further, the expandable pipe bottom plug further includes: a limiting device sleeved on the necking section, the limiting device having a limiting groove extending in the radial direction of the support shaft, the telescopic blocks are disposed in the limiting groove, and the necking section has a stepped surface, and the elastic member can abut the limiting device against the stepped surface.

[0009] Further, the limiting device includes a first limiting sleeve and a second limiting sleeve, and a limiting groove is formed between the first limiting sleeve and the second limiting sleeve.

[0010] Further, the limiting device further includes a limiting ring disposed at the bottom of the first limiting sleeve and extending downward, and at least a part of the limiting ring is located outside the circumferential direction of the telescopic block.

[0011] Further, the support shaft includes a shaft body and a stop sleeve screwed on the shaft body. The elastic member is a spring. The first end of the spring abuts against the lower surface of the limiting device, and the second end of the spring abuts against the upper surface of the stop sleeve.

[0012] Further, the shaft body includes a necking section and a straight cylinder section located below the necking section. A limiting protrusion is provided on the straight cylinder section. The bottom plug of the expansion tube further includes a third limiting sleeve sleeved on the straight cylinder section. The top end of the third limiting sleeve abuts against the lower surface of the limiting protrusion, and the bottom end of the third limiting sleeve abuts against the upper surface of the stop sleeve.

[0013] Further, the telescopic blocks are arranged at intervals in the circumferential direction of the support shaft.

[0014] Further, the support shaft includes a shaft body having a through hole and a blind plug disposed at the bottom of the shaft body.

[0015] According to another aspect of the present invention, there is provided an expansion tube cooperating with the above-mentioned bottom plug of the expansion tube, including: an upper section of the expansion tube, having an unexpanded state and an expanded state; a lower section of the expansion tube, disposed below the upper section of the expansion tube. The diameter of the lower section of the expansion tube is larger than the diameter of the upper section of the expansion tube in the unexpanded state and equal to the diameter of the upper section of the expansion tube in the expanded state. A mating groove cooperating with the telescopic structure of the bottom plug of the expansion tube is provided on the inner wall of the lower section of the expansion tube. In the case where the telescopic structure is in the extended position, at least a part of the telescopic structure extends into the mating groove.

[0016] Further, a guiding inclined surface is provided at the upper edge of the telescopic structure, and a mating inclined surface cooperating with the guiding inclined surface is provided on the groove wall of the mating groove.

[0017] According to still another aspect of the present invention, there is provided a method for fishing the bottom plug of the expansion tube, using the above-mentioned bottom plug of the expansion tube and the above-mentioned expansion tube. The fishing method includes: Step S10: Connect the fishing tool to the support shaft of the bottom plug of the expansion tube; Step S20: Lift the support shaft upward. Under the action of the lifting force, the support shaft cooperates with the telescopic structure to move the telescopic structure from the extended position to the retracted position, so that the telescopic structure disengages from the mating groove on the lower section of the expansion tube of the expansion tube.

[0018] Applying the technical solution of the present invention, when the telescopic structure of the bottom plug of the expansion tube is in the extended position, it can abut against the expansion tube to form an expansion tube assembly. When repairing the casing, the above-mentioned expansion tube assembly is lowered to a predetermined position, and then the expansion tube is expanded by an expansion cone. After the expansion tube is expanded, to restore the wellbore passage, a fishing tool is connected to the support shaft, and the telescopic structure is moved to the recovery position. At this time, the bottom plug of the expansion tube is separated from the expansion tube, and the bottom plug of the expansion tube can be lifted out as a whole through the fishing tool. The above structure enables no drilling and grinding operations to be carried out when restoring the wellbore passage. On the one hand, no metal fragments will fall into the well, which will not affect the later oil production operations; on the other hand, it can reduce the operation time and improve the operation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings forming a part of this application are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0020] Figure 1 It shows a partial cross-sectional schematic view of an embodiment of the bottom plug of the expansion tube according to the present invention;

[0021] Figure 2 It shows Figure 1 a partial cross-sectional schematic view of the bottom plug of the expansion tube after being fitted with the expansion tube;

[0022] Figure 3 It shows Figure 2 an enlarged schematic view of the structure at A of the bottom plug of the expansion tube after being fitted with the expansion tube;

[0023] Figure 4 It shows Figure 1 a partial cross-sectional schematic view of the telescopic structure of the bottom plug of the expansion tube after being disengaged from the mating groove of the expansion tube;

[0024] Figure 5 It shows Figure 4 an enlarged schematic view of the structure at B of the bottom plug of the expansion tube; and

[0025] Figure 6 It shows a cross-sectional schematic view of the expansion tube after expansion of an embodiment of the expansion tube according to the present invention.

[0026] Wherein, the above-mentioned drawings include the following reference numerals:

[0027] 10. Support shaft; 11. Necking section; 111. Inclined surface; 112. Step surface; 12. Shaft body; 13. Stop sleeve; 14. Straight tube section; 15. Limit projection; 16. Blind plug; 20. Telescopic structure; 21. Telescopic block; 211. Guide inclined surface; 30. Elastic member; 40. Position limiting device; 41. First position limiting sleeve; 42. Second position limiting sleeve; 43. Position limiting ring; 50. Third position limiting sleeve; 60. Upper section of expansion tube; 70. Lower section of expansion tube; 71. Matching groove; 711. Matching inclined surface; 100. Fishing tool; 200. Expansion cone; 300. Oil pipe. Detailed implementation manners

[0028] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the drawings and in combination with the embodiments.

[0029] As Figures 1 to 5 shown, the bottom plug of the expansion tube in this embodiment includes: a support shaft 10 and a telescopic structure 20. Among them, the bottom end of the support shaft 10 is the plugging end. The telescopic structure 20 is arranged on the support shaft 10. The telescopic structure 20 has a retracted position and an extended position where it expands outwards. The telescopic structure 20 can move from the extended position to the retracted position under the action of an external force.

[0030] Applying the technical solution of the application example, when the telescopic structure 20 of the bottom plug of the expansion tube is in the extended position, it can abut against the expansion tube to form an expansion tube assembly. When repairing the casing, the above expansion tube assembly is lowered to a predetermined position, and then the expansion tube is expanded by an expansion cone. When the expansion tube expands, in order to restore the wellbore passage, a fishing tool is connected to the support shaft 10, and the telescopic structure 20 is moved to the retracted position. At this time, the bottom plug of the expansion tube is separated from the expansion tube, and the bottom plug of the expansion tube can be lifted out integrally through the fishing tool. The above structure enables no drilling and grinding operation to be carried out when restoring the wellbore passage. On the one hand, no metal fragments will fall into the well, which will not affect the later oil production operation; on the other hand, the operation time can be reduced and the operation efficiency can be improved.

[0031] It should be noted that in this embodiment, the bottom plug of the expansion tube can be reused in cooperation with a new expansion tube after being fished out, which reduces the operation cost.

[0032] As Figures 1 to 5As shown, in this embodiment, the telescopic structure 20 includes a telescopic block 21 that moves radially along the support shaft 10. The expandable pipe bottom plug further includes: an elastic member 30 disposed between the telescopic block 21 and the support shaft 10. Specifically, when the expandable pipe bottom plug is installed into the expandable pipe, the telescopic block 21 abuts against the expandable pipe, so that the relative position between the expandable pipe bottom plug and the expandable pipe remains unchanged. And when it is necessary to restore the wellbore passage, the telescopic block 21 can contract under an external force and separate from the expandable pipe. At this time, the expandable pipe bottom plug can be lifted out by a fishing tool. The above structure is simple and easy to implement. It should be noted that in this embodiment, the elastic member 30 can support the telescopic block 21, and at the same time, the telescopic block 21 can move relative to the support shaft 10. Of course, in other embodiments, the elastic member can be located between the telescopic block and the support shaft in the radial direction of the support shaft. The above telescopic block can abut against the expandable pipe under the elastic force of the elastic member. In another embodiment not shown in the figure, the telescopic structure can move between the extended position and the retracted position through a driving device, or the telescopic structure itself has elasticity and expands when heated, and its outer surface can move to the extended position, and contracts when cooled, and its outer surface can return to the retracted position.

[0033] As Figures 1 to 5 shown, in this embodiment, the support shaft 10 includes a necking section 11. The outer wall of the necking section 11 includes an inclined surface 111. The inclined surface 111 gradually contracts in the direction from the top end to the bottom end of the support shaft 10. The elastic member 30 is located below the telescopic block 21 to support the telescopic block 21. The telescopic block 21 can slide along the inclined surface 111 under the action of an external force to switch between the extended position and the retracted position. Specifically, when restoring the wellbore passage, first connect the fishing tool to the support shaft 10, and then lift the support shaft 10. When the lifting force is greater than the supporting force of the elastic member 30, the elastic member 30 is compressed, and at the same time, the telescopic block 21 slides along the inclined surface 111 of the support shaft 10. Since the inclined surface 111 gradually contracts in the direction from the top end to the bottom end of the support shaft 10, when sliding a certain distance, the telescopic block 21 retracts in the radial direction, resulting in a reduction in the outer diameter, so that the entire expandable pipe bottom plug is lifted out of the pipe. The above structure is simple. Just by lifting the support shaft 10, the expandable pipe bottom plug can be taken out, reducing the operation steps of the operators, improving the operation efficiency, and reducing the labor intensity. In addition, since no other driving member for driving the telescopic block 21 to move is provided, the cost is low.

[0034] As Figures 1 to 5As shown, in this embodiment, the bottom plug of the expansion tube further includes a limiting device 40 sleeved on the necking section 11. The limiting device 40 has a limiting groove extending in the radial direction of the support shaft 10. The telescopic block 21 is arranged in the limiting groove. The necking section 11 has a step surface 112, and the elastic member 30 can abut the limiting device 40 against the step surface 112. The above structure can limit the position of the telescopic block 21 in the axial direction of the support shaft 10. In addition, the above structure enables the telescopic block 21 to move only in a predetermined direction when extending and contracting. The above structure ensures the reliability of the bottom plug of the expansion tube.

[0035] As Figures 1 to 5 shown, in this embodiment, the limiting device 40 includes a first limiting sleeve 41 and a second limiting sleeve 42, and a limiting groove is formed between the first limiting sleeve 41 and the second limiting sleeve 42. The above structure is simple and convenient for processing.

[0036] As Figures 1 to 5 shown, in this embodiment, the limiting device 40 further includes a limiting ring 43. The limiting ring 43 is arranged at the bottom of the first limiting sleeve 41 and extends downward, and at least part of the limiting ring 43 is located on the circumferential outer side of the telescopic block 21. The above structure can prevent the telescopic block 21 from slipping out of the limiting groove between the first limiting sleeve 41 and the second limiting sleeve 42.

[0037] As Figure 1 and Figure 2 shown, in this embodiment, the support shaft 10 includes a shaft body 12 and a stop sleeve 13 screwed on the shaft body 12. The elastic member 30 is a spring. The first end of the spring abuts against the lower surface of the limiting device 40, and the second end of the spring abuts against the upper surface of the stop sleeve 13. The above structure is simple and convenient for assembly.

[0038] As Figure 1 , Figure 2 and Figure 4 shown, in this embodiment, the shaft body 12 includes a necking section 11 and a straight cylinder section 14 located below the necking section 11. A limiting protrusion 15 is arranged on the straight cylinder section 14. The bottom plug of the expansion tube further includes a third limiting sleeve 50 sleeved on the straight cylinder section 14. The top end of the third limiting sleeve 50 abuts against the lower surface of the limiting protrusion 15, and the bottom end of the third limiting sleeve 50 abuts against the upper surface of the stop sleeve 13. The above third limiting sleeve 50 has the following three advantages: First, the above structure can control the compression amount of the spring according to actual needs, so as to control the elastic force of the spring. Second, the above structure can prevent the spring from being compressed and combined, ensuring that the bottom plug of the expansion tube can move relative to the expansion tube; Third, the above structure can play a guiding role for the spring, avoiding the axis of the spring from tilting when it is compressed.

[0039] In this embodiment, the telescopic blocks 21 are multiple blocks arranged at intervals in the circumferential direction of the support shaft 10. The above structure enables the bottom plug of the expansion tube to more reliably abut against the expansion tube when the telescopic structure 20 is in the extended position.

[0040] As Figure 1 and Figure 2 shown, in this embodiment, the support shaft 10 includes a shaft body 12 having a through hole and a blind plug 16 provided at the bottom of the shaft body 12. The above structure is simple and easy to machine and assemble. Specifically, the bottom plug of the expansion tube is located at the bottom of the expansion tube. To expand the expansion tube, an expansion cone 200 and a tubing 300 connected to the expansion cone are further provided inside the expansion tube. During operation, pressure fluid is injected into the tubing 300. As the pressure fluid accumulates at the blind plug 16, the pressure fluid provides an upward pressure for the expansion cone 200, causing the expansion cone 200 to move upward. As the expansion cone moves upward, the expansion tube is pushed outward by the expansion cone, thereby expanding the expansion tube.

[0041] As Figure 2 , Figure 4 and Figure 6 shown, the present application also provides an expansion tube that cooperates with the above-mentioned bottom plug of the expansion tube, including: an upper section 60 of the expansion tube and a lower section 70 of the expansion tube. Among them, the upper section 60 of the expansion tube has an unexpanded state and an expanded state. The lower section 70 of the expansion tube is provided below the upper section 60 of the expansion tube. The diameter of the lower section 70 of the expansion tube is greater than the diameter of the upper section 60 of the expansion tube in the unexpanded state and equal to the diameter of the upper section 60 of the expansion tube in the expanded state. A mating groove 71 that cooperates with the telescopic structure 20 of the bottom plug of the expansion tube is provided on the inner wall of the lower section 70 of the expansion tube. In the case where the telescopic structure 20 is in the extended position, at least a part of the telescopic structure 20 extends into the mating groove 71.

[0042] Applying the technical solution of the application example, when the telescopic structure 20 of the bottom plug of the expansion tube is in the extended position, at least a part of the telescopic structure 20 extends into the mating groove 71, so that the bottom plug of the expansion tube is installed together with the expansion tube to form an expansion tube assembly. When repairing the casing, the above-mentioned expansion tube assembly is lowered to a predetermined position, and then the expansion tube is expanded by the expansion cone. After the expansion tube is expanded, to restore the wellbore passage, a fishing tool is connected to the support shaft 10, and the telescopic structure 20 is moved to the recovery position. At this time, the telescopic structure 20 of the bottom plug of the expansion tube disengages from the mating groove 71, and the bottom plug of the expansion tube can be integrally lifted out by the fishing tool. The above structure enables no drilling and grinding operations to be carried out when restoring the wellbore passage. On the one hand, no metal fragments will fall into the well, which will not affect the later oil production operations; on the other hand, the operation time can be reduced and the operation efficiency can be improved.

[0043] As Figures 2 to 6As shown, in this embodiment, a guiding inclined surface 211 is provided at the upper edge of the telescopic structure 20, and a mating inclined surface 711 that mates with the guiding inclined surface 211 is provided on the wall of the mating groove 71. The above structure enables the telescopic structure 20 to be more easily disengaged from the mating groove 71 under the guidance of the guiding inclined surface 211 when the support shaft 10 is lifted upward. Of course, in other embodiments not shown in the figure, the guiding inclined surface can also be provided on the lower surface of the telescopic structure 20, and the guiding inclined surface gradually slopes downward from the outside to the inside. The above structure enables the telescopic structure 20 to have a component force towards the inclined surface 111 under the action of the elastic force of the spring, so that the telescopic structure 20 is closely attached to the inclined surface 111. In this way, as the support shaft 10 is lifted upward, the telescopic block 21 slides along the inclined surface 111 of the support shaft 10 and retracts in the radial direction, reducing the outer diameter, so that the entire expansion pipe bottom plug is lifted out of the pipe.

[0044] This application also provides a fishing method, which uses the above-mentioned expansion pipe bottom plug and the above-mentioned expansion pipe. The fishing method includes: Step S10: Connect the fishing tool 100 to the support shaft 10 of the expansion pipe bottom plug; Step S20: Lift the support shaft 10 upward. Under the action of the lifting force, the support shaft 10 cooperates with the telescopic structure 20 to move the telescopic structure 20 from the extended position to the retracted position, so that the telescopic structure 20 is disengaged from the mating groove 71 on the lower section 70 of the expansion pipe of the expansion pipe. The above structure is simple. Just by lifting the support shaft 10, the expansion pipe bottom plug can be taken out, reducing the operation steps of the operators, improving the operation efficiency, and reducing the labor intensity.

[0045] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An expansion pipe bottom plug, characterized in that, Comprising: A support shaft (10), the bottom end of the support shaft (10) being a sealed end; A telescopic structure (20), arranged on the support shaft (10), the telescopic structure (20) having a retracted position and an extended position where it expands outwards, and the telescopic structure (20) being able to move from the extended position to the retracted position under the action of an external force; The telescopic structure (20) includes a telescopic block (21) that moves radially along the support shaft (10), and the expansion tube bottom plug further includes: An elastic member (30), arranged between the telescopic block (21) and the support shaft (10); The support shaft (10) includes a necked-down section (11), the outer wall of the necked-down section (11) including an inclined surface (111), the inclined surface (111) gradually contracting in the direction from the top end to the bottom end of the support shaft (10), the elastic member (30) being located below the telescopic block (21) to support the telescopic block (21), and the telescopic block (21) being able to slide along the inclined surface (111) under the action of an external force to switch between the extended position and the retracted position; The expansion tube bottom plug further includes: A limiting device (40), sleeved on the necked-down section (11), the limiting device (40) having a limiting groove extending in the radial direction of the support shaft (10), the telescopic block (21) being arranged in the limiting groove, the necked-down section (11) having a stepped surface (112), and the elastic member (30) being able to abut the limiting device (40) against the stepped surface (112); The limiting device (40) includes a first limiting sleeve (41) and a second limiting sleeve (42), and the limiting groove is formed between the first limiting sleeve (41) and the second limiting sleeve (42); The limiting device (40) further includes a limiting ring (43), the limiting ring (43) being arranged at the bottom of the first limiting sleeve (41) and extending downwards, and at least part of the limiting ring (43) being located on the circumferential outer side of the telescopic block (21); The support shaft (10) includes a shaft body (12) and a stop sleeve (13) screwed onto the shaft body (12), the elastic member (30) being a spring, the first end of the spring abutting against the lower surface of the limiting device (40), and the second end of the spring abutting against the upper surface of the stop sleeve (13).

2. The expansion tube bottom plug according to claim 1, characterized in that, The shaft body (12) includes the necked-down section (11) and a straight tube section (14) located below the necked-down section (11), the straight tube section (14) being provided with a limiting protrusion (15), the expansion tube bottom plug further including a third limiting sleeve (50), the third limiting sleeve (50) being sleeved on the straight tube section (14), the top end of the third limiting sleeve (50) abutting against the lower surface of the limiting protrusion (15), and the bottom end of the third limiting sleeve (50) abutting against the upper surface of the stop sleeve (13).

3. The expansion tube bottom plug according to claim 1, wherein, The telescopic blocks (21) are multiple and arranged at intervals in the circumferential direction of the support shaft (10).

4. The expansion tube bottom plug according to claim 1, wherein, The support shaft (10) includes a shaft body (12) having a through hole and a blind plug (16) provided at the bottom of the shaft body (12).

5. An expansion tube adapted to cooperate with the expansion tube bottom plug according to any one of claims 1 to 4, comprising: An upper section (60) of the expansion tube, having an unexpanded state and an expanded state; A lower section (70) of the expansion tube, provided below the upper section (60) of the expansion tube. The diameter of the lower section (70) of the expansion tube is greater than the diameter of the upper section (60) of the expansion tube in the unexpanded state and equal to the diameter of the upper section (60) of the expansion tube in the expanded state. It is characterized in that a mating groove (71) adapted to cooperate with the telescopic structure (20) of the expansion tube bottom plug is provided on the inner wall of the lower section (70) of the expansion tube. In the case where the telescopic structure (20) is in the extended position, at least a part of the telescopic structure (20) extends into the mating groove (71).

6. The expandable tube according to claim 5, wherein A guiding inclined surface (211) is provided at the upper edge of the telescopic structure (20), and a mating inclined surface (711) adapted to cooperate with the guiding inclined surface (211) is provided on the groove wall of the mating groove (71).

7. A fishing method for fishing the bottom plug of an expandable pipe, characterized in that, Using the expansion tube bottom plug according to any one of claims 1 to 4 and the expansion tube according to claim 5 or 6, the fishing method comprises: Step S10: Connect a fishing tool (100) to the support shaft (10) of the expansion tube bottom plug; Step S20: Lift the support shaft (10) upward. Under the action of the lifting force, the support shaft (10) cooperates with the telescopic structure (20) to move the telescopic structure (20) from the extended position to the retracted position, so that the telescopic structure (20) disengages from the mating groove (71) on the lower section (70) of the expansion tube of the expansion tube.

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