Soluble key opening multistage fracturing sliding sleeve

Abstract

The invention provides a soluble key opening multistage fracturing sliding sleeve, and relates to the technical field of oil and gas field operation construction tools. The invention discloses a multi-stage fracturing sliding sleeve, which belongs to a separate layer fracturing tool and can be used for multi-stage fracturing of a well cementation pipe column or separate layer fracturing in a pipe. Wherein the soluble key is of a solid structure, the high-pressure construction strength requirement is met, after fracturing construction is finished, the soluble key is completely dissolved, and the large-drift-diameter multi-stage fracturing sliding sleeve requirement is met; meanwhile, a structure similar to a lock cylinder is designed in the sliding sleeve, only a corresponding soluble key can successfully open the sliding sleeve, according to the principle, multiple keys and multiple lock cylinders can be designed, one key corresponds to one lock cylinder, the fracturing sliding sleeve of the same size can meet the fracturing construction requirements of dozens of layers, after fracturing is finished, the soluble key is automatically dissolved, and therefore the fracturing sliding sleeve can be opened successfully. The inner diameters of all the sliding sleeves are the same, so that the purpose of full bore of the sliding sleeves is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas field operation construction tools, in particular to a multi-stage fracturing sliding sleeve that can be opened with a soluble key. Background Art

[0002] Multilayer fracturing is currently the main means of increasing production in tight oil reservoirs. Special tools are needed for staged fracturing. The main staged fracturing tools currently include coiled tubing drag fracturing tools, ball-dropping sleeve fracturing tools, and Infinitus fracturing sleeve tools. Coiled tubing drag fracturing requires coiled tubing equipment, and the casing is shot through by sandblasting perforation, which is not conducive to offshore platform operations. At the same time, there are problems such as difficult to control perforation quality and long operation time.

[0003] Among them, the ball-dropping sleeve is a relatively mature fracturing tool. Its ball seat is gradually reduced in diameter, so the number of fracturing stages is limited by the inner diameter. For small-sized tubing, it is difficult to achieve multi-layer staged fracturing goals due to the small inner diameter. The Infinitus fracturing sleeve is opened by a soluble ball with an elastic ratchet sleeve. In actual application, there are two problems: 1. The elastic pawl itself has low strength. During high-pressure (≥70MPa) construction, the soluble ball exerts a large thrust on the elastic pawl, which can reach tens of tons, and the pawl sleeve is easily crushed; 2. After the fracturing construction is completed, the soluble ball dissolves, while the elastic ratchet sleeve is insoluble. The inner diameter of the elastic ratchet sleeve is the inner diameter of the multi-stage fracturing sleeve, which cannot meet the requirements of the layered fracturing tool of the large-diameter multi-stage fracturing sleeve.

[0004] In order to solve the above problems, we propose a soluble key to open the multi-stage fracturing sleeve to solve the above problems. Summary of the invention

[0005] In order to solve the problems in the background technology, the present invention provides a soluble key for opening a multi-stage fracturing sleeve.

[0006] To achieve the above object, the technical solution adopted by the present invention is: A multi-stage fracturing sleeve opened by a soluble key comprises an upper joint and a lower joint installed at the right end of the upper joint; the upper joint is threadedly connected to the lower joint and locked by multiple sets of fixing pins, two sets of second seals are arranged at the connection between the upper joint and the lower joint, and the two sets of second seals are used to seal the connection between the upper joint and the lower joint; a core sleeve is arranged in the inner cavity of the upper joint, four sets of first seals are arranged on the left side of the outer surface of the core sleeve, a stopper sleeve is connected to the middle part of the right end of the core sleeve, and locked by multiple sets of shear pins, and the stopper sleeve is located in the inner cavity of the lower joint; A plurality of groups of locking blocks are evenly installed in the middle of both ends of the core sleeve in a circumferential direction, and two groups of spring pieces are arranged in the middle of the outer surface of the locking block, and the outer wall of the spring piece is in contact with the inner cavity of the upper joint; a soluble key is arranged in the inner cavity of the core sleeve, and the soluble key is clamped in the inner middle part of the locking block.

[0007] Preferably, the left end opening of the upper joint is set as an internal thread structure, the right end opening surface of the upper joint is set as an external thread structure, and two groups of first sealing installation grooves are opened on the right side of the external thread structure, and two groups of second sealing members are respectively installed in the two groups of first sealing installation grooves.

[0008] Preferably, a through-type liquid-passing hole is provided in the middle of the left end of the upper joint, wherein when the core sleeve is located on the left side of the inner cavity of the upper joint, the liquid-passing hole is sealed.

[0009] Preferably, the inner hole of the lower joint is set as a double-step structure, a limiting groove is set on the right side of the inner hole of the lower joint, a plurality of groups of pin threaded holes are evenly opened circumferentially at the left end of the lower joint, the left end opening of the lower joint is set as an internal thread structure, and the outer surface of the right end of the lower joint is set as an external thread structure.

[0010] Preferably, four groups of second sealing installation grooves are provided at the left end of the core sleeve, and the four groups of the first sealing members are respectively installed in the four groups of second sealing installation grooves. A plurality of groups of countersunk long holes are provided in the middle of the core sleeve, and the locking blocks are installed in the countersunk long holes.

[0011] Preferably, a plurality of groups of shear pin threaded holes and retaining ring grooves are provided at the right end of the core sleeve, the retaining ring grooves are located on the right side of the shear pin threaded holes, and elastic retaining rings are installed in the retaining ring grooves.

[0012] Preferably, the outer surface of the locking block is provided with two groups of spring plate grooves, the two groups of spring plates are respectively installed in the two groups of spring plate grooves, and the right side of the inner wall of the locking block is provided with two groups of tooth grooves.

[0013] Preferably, sealing grooves are provided at both ends of the outer surface of the soluble key, a V-shaped seal is installed in the inner middle part of the sealing groove, and two groups of lock teeth are provided in the middle part of the soluble key, wherein when the soluble key is installed into the core sleeve, the two groups of lock teeth are meshed and connected with the two groups of tooth grooves.

[0014] Preferably, a locking groove is provided on the left end surface of the stop sleeve; wherein, when the stop sleeve is installed on the right end of the core sleeve, the locking groove is located on the inner side of the shear pin threaded hole and is in an overlapping state, and the shear pin is inserted into the locking groove through the shear pin threaded hole, so that the connection between the core sleeve and the stop sleeve is locked.

[0015] Preferably, the main bodies of the first sealing member and the second sealing member are both sealing rings, and sealing ring retaining rings are provided at both ends of the sealing rings.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention discloses a multi-stage fracturing sleeve opened by a soluble key, which belongs to a layered fracturing tool and can be used for multi-stage fracturing of a cementing pipe string or layered fracturing in a pipe. The present invention discloses a multi-stage fracturing sleeve opened by a soluble key, wherein the soluble key has a solid structure and meets the requirements of high-pressure (≥70MPa) construction strength. After the fracturing construction is completed, the soluble key is completely dissolved, which meets the requirements of a large-diameter multi-stage fracturing sleeve. At the same time, a structure similar to a lock core is designed inside the sleeve, and only the corresponding soluble key can successfully open it. Based on this principle, multiple keys and multiple lock cores can be designed, and one key corresponds to one lock core, so that the same size of fracturing sleeve can meet the fracturing construction requirements of dozens of layers. After fracturing is completed, the soluble key dissolves by itself, and the inner diameters of all sleeves are the same, thereby achieving the goal of full-diameter sleeves. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a cross-sectional view of the closed state of the multi-stage fracturing sliding sleeve of the present invention; Figure 2 This is a cross-sectional view of the multi-stage fracturing sliding sleeve of the present invention in an open state; Figure 3 It is a cross-sectional view of the upper joint in the present invention; Figure 4 It is a cross-sectional view of the lower joint in the present invention; Figure 5 It is a cross-sectional view of the core sleeve of the present invention; Figure 6 It is a cross-sectional view of the baffle sleeve in the present invention; Figure 7 It is a cross-sectional view of the soluble key in the present invention; Figure 8 It is a cross-sectional view of the locking block in the present invention; Fig. 9 It is a cross-sectional view of the meshing state of the lock teeth of the soluble key and the tooth groove in the present invention.

[0018] In the figure: 1, upper joint; 2, core sleeve; 3, soluble key; 4, lock block; 5, spring piece; 6, stop sleeve; 7, lower joint; 8, first sealing member; 9, V-shaped seal; 10, set pin; 11, second sealing member; 12, shear pin; 13, elastic retaining ring; 101, first sealing installation groove; 102, liquid hole; 201, second sealing installation groove; 202, countersunk long hole; 203, shear nail threaded hole; 204, retaining ring groove; 301, sealing groove; 302, locking tooth; 401, spring plate groove; 402, tooth groove; 601, locking groove; 701, pin threaded hole; 702, limit groove. DETAILED DESCRIPTION

[0019] The technical solution in the embodiment of the present application is to solve the problems of the above-mentioned background technology, and the overall idea is as follows: Example: Refer to Figure 1 - Fig. 9 As shown, a soluble key-opening multi-stage fracturing sleeve of this embodiment includes an upper joint 1 and a lower joint 7 installed at the right end of the upper joint 1; the upper joint 1 and the lower joint 7 are threadedly connected and locked by multiple sets of fixing pins 10, and two sets of second sealing members 11 are provided at the connection between the upper joint 1 and the lower joint 7, and the two sets of second sealing members 11 are used to seal the connection between the upper joint 1 and the lower joint 7; Among them, the left end opening of the upper joint 1 is set as an internal thread structure, and the right end opening surface of the upper joint 1 is set as an external thread structure, and two groups of first sealing installation grooves 101 are opened on the right side of the external thread structure, and two groups of second sealing members 11 are respectively installed in the two groups of first sealing installation grooves 101.

[0020] The inner hole of the lower joint 7 is set as a double-step structure, a limiting groove 702 is set on the right side of the inner hole of the lower joint 7, a plurality of groups of pin threaded holes 701 are evenly opened in the circumferential direction at the left end of the lower joint 7, the left end opening of the lower joint 7 is set as an internal thread structure, and the outer surface of the right end of the lower joint 7 is set as an external thread structure.

[0021] A core sleeve 2 is arranged in the inner cavity of the upper joint 1, and four groups of first sealing members 8 are arranged on the left side of the outer surface of the core sleeve 2 to play a sealing role. A stop sleeve 6 is connected to the middle of the right end of the core sleeve 2 and is locked by multiple groups of shear nails 12. The stop sleeve 6 is located in the inner cavity of the lower joint 7; multiple groups of locking blocks 4 are evenly installed circumferentially in the middle of the two ends of the core sleeve 2, and two groups of spring plates 5 are arranged in the middle of the outer surface of the locking block 4, and the outer wall of the spring plate 5 is in contact with the inner cavity of the upper joint 1; a soluble key 3 is arranged in the inner cavity of the core sleeve 2, and the soluble key 3 is clamped in the inner middle of the locking block 4, and the spring plate 5 acts as an elastic force on the locking block 4, so that the soluble key 3 can slide down until it is locked with the locking block 4.

[0022] Four groups of second sealing installation grooves 201 are arranged at the left end of the core sleeve 2, and four groups of first sealing members 8 are respectively installed in the four groups of second sealing installation grooves 201. The arrangement of the four groups of first sealing members 8 plays a sealing role, so that the core sleeve 2 is sealed and installed in the inner cavity of the upper joint 1. A plurality of groups of circumferentially distributed countersunk long strip holes 202 are arranged in the middle part of the core sleeve 2, and the locking block 4 is installed in the countersunk long strip hole 202.

[0023] A through-type liquid hole 102 is provided in the middle of the left end of the upper joint 1. When the core sleeve 2 is located on the left side of the inner cavity of the upper joint 1, the liquid hole 102 is sealed. On the contrary, when the core sleeve 2 slides down, the liquid hole 102 leaks out. In some examples, the right end of the core sleeve 2 is provided with multiple groups of shear pin thread holes 203 and retaining ring grooves 204, the retaining ring grooves 204 are located on the right side of the shear pin thread holes 203, and an elastic retaining ring 13 is installed in the retaining ring grooves 204, wherein the multiple groups of shear pin thread holes 203 are evenly distributed circumferentially.

[0024] In some examples, two groups of spring clip grooves 401 are provided on the outer surface of the locking block 4, and two groups of spring clips 5 are respectively installed in the two groups of spring clip grooves 401, and two groups of tooth grooves 402 are provided on the right side of the inner wall of the locking block 4; sealing grooves 301 are provided at both ends of the outer surface of the soluble key 3, and a V-shaped seal 9 is installed in the middle of the inner side of the sealing groove 301, and two groups of lock teeth 302 are provided in the middle of the soluble key 3.

[0025] When the soluble key 3 is installed in the core sleeve 2 , the two groups of lock teeth 302 are meshed and connected with the two groups of tooth grooves 402 .

[0026] In some examples, a locking groove 601 is provided on the left end surface of the stop sleeve 6; wherein, when the stop sleeve 6 is installed on the right end of the core sleeve 2, the locking groove 601 is located on the inner side of the shear pin threaded hole 203 and is in an overlapping state, and the shear pin 12 is inserted into the locking groove 601 through the shear pin threaded hole 203, so that the connection between the core sleeve 2 and the stop sleeve 6 is locked.

[0027] In some examples, the main bodies of the first sealing member 8 and the second sealing member 11 are both sealing rings, and sealing ring retaining rings are provided at both ends of the sealing rings to improve the sealing effect.

[0028] The working principle of the present invention is: Sliding sleeve in well state: During use, the sliding sleeve of the present invention is first connected to the completion string on the ground, and lowered into the target layer along with the completion string. At this time, the sliding sleeve is in a closed state, that is, the fluid hole 102 is in a closed state; Sleeve opening process: After the sleeve of the present invention is lowered into place along with the working pipe string, a soluble key 3 is dropped from the wellhead, and fracturing starts from the bottom fracturing sleeve. After the soluble key 3 enters the core sleeve 2, the locking teeth 302 on the soluble key 3 engage with the tooth grooves 402 on the locking block 4. At this time, the soluble key 3 is locked in the core sleeve 2, and the V-shaped seal 9 on the soluble key 3 forms a seal with the inner hole of the core sleeve 2; at this time, the pipe is pressurized so that the soluble key 3 drives the core sleeve 2 downward, thereby exposing the liquid hole 102, wherein the core sleeve 2 will cut off the shear pin 12 during the downward process, and automatically limit when the core sleeve 2 descends to the limit groove 702 of the inner hole of the lower joint 7, at this time, the elastic retaining ring 13 is inserted into the limit groove 702 of the lower joint 7 to lock the core sleeve 2.

[0029] Through the above steps, the final state is after the fracturing of the sliding sleeve is completed. Among them, after the layered fracturing construction is completed, the soluble key 3 dissolves by itself, and the inner diameters of all fracturing sliding sleeves are consistent.

[0030] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A soluble key for opening a multi-stage fracturing sleeve, characterized in that: It comprises an upper joint (1) and a lower joint (7) installed at the right end of the upper joint (1); The upper joint (1) and the lower joint (7) are threadedly connected and locked by a plurality of sets of fixing pins (10); two sets of second sealing members (11) are provided at the connection between the upper joint (1) and the lower joint (7); the two sets of second sealing members (11) are used to seal the connection between the upper joint (1) and the lower joint (7); A core sleeve (2) is arranged in the inner cavity of the upper joint (1), four groups of first sealing members (8) are arranged on the left side of the outer surface of the core sleeve (2), a stop sleeve (6) is connected to the middle of the right end of the core sleeve (2) and is locked by multiple groups of shear nails (12), and the stop sleeve (6) is located in the inner cavity of the lower joint (7); A plurality of groups of locking blocks (4) are evenly installed in the circumferential direction in the middle of the core sleeve (2), and two groups of spring pieces (5) are arranged in the middle of the outer surfaces of the plurality of groups of locking blocks (4), and the outer walls of the spring pieces (5) are in contact with the inner cavity of the upper joint (1); A soluble key (3) is arranged in the inner cavity of the core sleeve (2), and the soluble key (3) is clamped on the inner sides of the multiple groups of locking blocks (4).

2. A soluble key for opening a multi-stage fracturing sleeve according to claim 1, characterized in that: The left end opening of the upper joint (1) is arranged as an internal thread structure, the right end opening surface of the upper joint (1) is arranged as an external thread structure, and two groups of first sealing installation grooves (101) are arranged on the right side of the external thread structure, and the two groups of the second sealing members (11) are respectively installed in the two groups of first sealing installation grooves (101).

3. The method for opening a multi-stage fracturing sleeve with a soluble key according to claim 2, characterized in that: A through-type liquid passage hole (102) is provided in the middle of the left end of the upper joint (1), wherein when the core sleeve (2) is located on the left side of the inner cavity of the upper joint (1), the liquid passage hole (102) is sealed.

4. A soluble key for opening a multi-stage fracturing sleeve according to claim 3, characterized in that: The inner hole of the lower joint (7) is arranged as a double-step structure, a limiting groove (702) is arranged on the right side of the inner hole of the lower joint (7), a plurality of groups of pin threaded holes (701) are uniformly arranged at the left end of the lower joint (7) in a circumferential direction, the left end opening of the lower joint (7) is arranged as an internal thread structure, and the outer surface of the right end of the lower joint (7) is arranged as an external thread structure.

5. The method for opening a multi-stage fracturing sleeve with a soluble key according to claim 4 is characterized in that: The left end of the core sleeve (2) is provided with four groups of second sealing installation grooves (201), and the four groups of the first sealing members (8) are respectively installed in the four groups of second sealing installation grooves (201). The middle part of the core sleeve (2) is provided with a plurality of groups of countersunk long strip holes (202), and the locking blocks (4) are installed in the countersunk long strip holes (202).

6. The method for opening a multi-stage fracturing sleeve with a soluble key according to claim 5, characterized in that: The right end of the core sleeve (2) is provided with a plurality of groups of shear pin threaded holes (203) and retaining ring grooves (204); the retaining ring grooves (204) are located on the right side of the shear pin threaded holes (203); and an elastic retaining ring (13) is installed in the retaining ring grooves (204).

7. A soluble key for opening a multi-stage fracturing sleeve according to claim 6, characterized in that: The outer surface of the locking block (4) is provided with two groups of spring sheet grooves (401), the two groups of spring sheets (5) are respectively installed in the two groups of spring sheet grooves (401), and the right side of the inner wall of the locking block (4) is provided with two groups of tooth grooves (402).

8. The method for opening a multi-stage fracturing sleeve with a soluble key according to claim 7, characterized in that: The outer surface of the soluble key (3) is provided with sealing grooves (301) at both ends, a V-shaped seal (9) is installed in the middle of the inner side of the sealing groove (301), and two groups of lock teeth (302) are arranged in the middle of the soluble key (3), wherein when the soluble key (3) is installed in the core sleeve (2), the two groups of lock teeth (302) are meshed and connected with the two groups of tooth grooves (402).

9. A soluble key for opening a multi-stage fracturing sleeve according to claim 8, characterized in that: The left end surface of the stopper sleeve (6) is provided with a locking groove (601); When the stopper sleeve (6) is installed at the right end of the core sleeve (2), the locking groove (601) is located inside the shear pin threaded hole (203) and is in an overlapping state. The shear pin (12) passes through the shear pin threaded hole (203) and is inserted into the locking groove (601), thereby locking the connection between the core sleeve (2) and the stopper sleeve (6).

10. A soluble key for opening a multi-stage fracturing sleeve according to claim 9, characterized in that: The main bodies of the first sealing member (8) and the second sealing member (11) are both sealing rings, and sealing ring retaining rings are provided at both ends of the sealing rings.

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