A method to retrieve the fish top

Abstract

A method for retrieving a fish top belongs to the field of well repair operations. The method uses a fish top retrieval device to retrieve the drill bit, drilling tools, and casing that have fallen to the bottom of the well during drilling. When the fish top retrieval device descends to the depth of the fish top, the fish top retrieval device is blocked and the suspended weight is reduced; a certain pressure is maintained on the fish top, and the tension claws are retracted. The severely deviated fish top will be pulled back and forth as the tension claws are recovered; a small-sized oil pipe or drill pipe column is lowered to fix the fish top and pull out the fish top retrieval device. Beneficial effects: wide range of application, the expansion size and elasticity of the tension claw can be modified to adapt to different well conditions; the tension claw has a large extension range, it is easy to catch the fallen fish and pull the fallen fish back; simple operation, saving operating costs, and increasing economic benefits. After using this patented device, such abandoned oil and water wells can be repaired, thereby resuming production early and increasing economic benefits.

Description

Technical Field

[0001] The invention relates to a method for retrieving a fish top, and belongs to the field of well repair operations. Background Art

[0002] As oilfield development enters the middle and late stages, the production casing of oil wells often breaks. If the damaged position of the casing is not deep, the casing replacement and well repair operation is often carried out, and a new casing is lowered to replace the damaged casing. However, during the casing replacement and well repair operation, such as the well washing operation during casing milling, the formation is eroded, causing the lower fish top to seriously deviate from the wellbore trajectory, resulting in the loss of the fish top, and such wells cannot be repaired.

[0003] like Figure 1 As shown in the figure, the damaged casing on the top of this well has been removed during the well repair operation. The fish top is the 51 / 2" casing collar (103.98m), which has seriously deviated from the centerline of the wellbore. This well uses a Φ219mm casing milling pipe to find the fish, and can go down to 130m; using a Φ280mm casing milling pipe to find the fish, it can go down to 110m. The fish top could not be found in both searches. After calculation, it was found that the centerline of the fish top deviated from the centerline of the wellbore by 254mm, the inner side of the fish top deviated from the centerline of the wellbore by 162.81mm, and half of the inner diameter of the surface casing is 159mm, that is, the fish top has seriously deviated from the original wellbore trajectory.

[0004] There is no effective repair method for this type of wells at present, and repair is generally abandoned, resulting in significant economic losses. Therefore, there is an urgent need for a device for retrieving the fish top, so as to reconnect the lower casing and repair this type of wells. Summary of the invention

[0005] In order to effectively retrieve a severely deviated fish top, the present invention provides the following technical solution: A method for retrieving a fish top comprises the following steps:

[0006] S1. Slowly lower the fish top retrieval device into the oil pipe;

[0007] S2. When the fish top retrieval device is moving downward, when the fish top retrieval device is not out of the surface casing, the tension claw on the device will be constrained by the surface casing, and the tension claw will slide downward close to the inner wall of the surface casing;

[0008] S3. When the fish top retrieval device descends out of the surface casing, the tension claws on the device will slide downward closely against the inner wall of the open hole section;

[0009] S4. The fish top retrieval device continues to move downward, and the fingers of the tension claw are evenly distributed around the circumference, and the fish top can be detected in all directions.

[0010] S5. When the fish top retrieval device descends to the fish top depth, it continues to descend until the tension claw is inserted into the lower fish top. At this time, the fish top retrieval device is blocked and the hanging weight is reduced;

[0011] S6. Maintain a certain pressure on the fish top, and then start to throw a ball to the fish top retrieval device to pressurize it. The hydraulic cylinder sleeve of the device moves downward, and the tension claws are retracted. The seriously deviated fish top will be pulled back and forth as the tension claws are retracted;

[0012] S7. Run a small-sized tubing or drill pipe string through the fish top and into the casing, thereby fixing the fish top and lifting the fish top retrieval device;

[0013] S8. Perform subsequent casing tie-back operations.

[0014] An eccentric casing catcher comprises a coupling, a straightening body, a center tube, a liquid cylinder sleeve, a sealing ring, a steel ball and a tension claw; the coupling is sleeved on the top of the straightening body, the center tube is arranged inside the straightening body, the liquid cylinder sleeve is sleeved on the bottom of the straightening body, and a plurality of tension claws are inserted into the bottom of the straightening body.

[0015] Furthermore, the centralizing body is threadedly connected to the coupling.

[0016] Furthermore, a sealing ring is provided between the lower part of the centralizing body and the cylinder sleeve.

[0017] Furthermore, the inner diameter of the cylinder sleeve is larger than the outer diameter of the sealing ring.

[0018] Furthermore, the inner diameter of the sealing ring is larger than the outer diameter of the central tube.

[0019] Furthermore, the minimum cross-sectional dimension of the centralizing body is larger than the outer diameter of the central tube.

[0020] Furthermore, the fingers of the plurality of tension claws are evenly distributed along the circumference, and each tension claw includes a fixed straight line segment, an arc segment and a straight line grasping segment.

[0021] Furthermore, the tension claws are made of elastic steel bars with a diameter of 10 mm.

[0022] Furthermore, a steel ball is arranged inside the central tube.

[0023] Furthermore, the diameter of the steel ball is smaller than the inner diameter of the central tube.

[0024] Furthermore, a circular boss is provided on the outer circumference of the central tube, and the bottom of the circular boss is located on the upper part of the boss of the cylinder sleeve.

[0025] Furthermore, a limiting structure is provided on the inner side of the cylinder sleeve, and the limiting structure matches with the top of the circular boss of the central tube.

[0026] Furthermore, the coupling, the centralizing body, the center tube, the cylinder sleeve, and the steel ball are made of No. 45 steel.

[0027] Furthermore, the sealing ring is made of rubber.

[0028] Furthermore, the fish top is the top of the drill bit, drilling tools, and casing that falls to the bottom of the well during the drilling process.

[0029] Furthermore, an overflow hole is provided at the lower portion of the circular boss.

[0030] Furthermore, the inner wall of the central tube is provided with a convex edge, and a steel ball is provided on the convex edge.

[0031] Furthermore, the ball throwing and pressure in step S6 refers to throwing a steel ball into the fish top retrieval device, and the steel ball falls on the convex edge of the inner wall of the central tube to form a seal; then water is injected into the central tube of the fish top retrieval device, and the water will flow out from the overflow hole. Under the action of water pressure, the limiting structure of the liquid cylinder sleeve will drive the liquid cylinder sleeve downward.

[0032] Beneficial effects: The present invention provides an eccentric casing catcher, which has the following beneficial effects:

[0033] (1) Wide range of applications

[0034] The device can modify the expansion size and elasticity of the tension claw according to the specific well conditions to adapt to different well conditions. Therefore, the tension claw has a large extension range and can easily catch the fallen fish and pull it back.

[0035] (2) Easy to operate

[0036] The device is easy to operate and can easily capture the deviated casing, and the retraction action can be completed by simply pressing the oil pipe.

[0037] (3) Save operating costs and increase economic benefits

[0038] After using this patented device, such abandoned oil and water wells can be repaired, thereby resuming production early and increasing economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a schematic diagram of the well body structure of the case well;

[0040] Figure 2 This is a schematic diagram of the initial state of the fish top retrieval device;

[0041] Figure 3 A schematic diagram of the fish top retrieval device in a folded state;

[0042] Figure 4 This is a state diagram of the fish top retrieval device in the surface casing;

[0043] Figure 5Naked eye time state diagram of the fish top retrieval device;

[0044] Figure 6 This is a state diagram of the tension claw of the fish top retrieval device when it is inserted into the lower fish top;

[0045] Figure 7 Schematic diagram of the casing being pulled back after the fish top retrieval device was pressed;

[0046] Figure 8 Schematic diagram of inserting small size tubing for fish top retrieval device;

[0047] Fig. 9 Diagram of the wellbore structure after the fish top retrieval device is removed.

[0048] Explanation of the serial numbers in the figure: 1. Coupling; 2. Straightening body; 3. Center pipe; 4. Cylinder sleeve; 5. Sealing ring; 6. Steel ball; 7. Tension claw. DETAILED DESCRIPTION

[0049] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the present invention will be described in detail below in combination with the accompanying drawings and detailed embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0050] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0051] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0052] Secondly, the present invention is described in detail with reference to schematic diagrams. When describing the embodiments of the present invention in detail, for the sake of convenience, the cross-sectional diagrams showing the device structure will not be partially enlarged according to the general scale, and the schematic diagrams are only examples, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional dimensions of length, width and depth should be included.

[0053] The following is combined with Figures 1 to 9 The present invention is further described in detail with specific embodiments: This application is further described with this example.

[0054] Example 1

[0055] like Figure 2As shown, this embodiment provides a method for retrieving a fish top, comprising the following steps:

[0056] S1. Slowly lower the fish top retrieval device into the oil pipe;

[0057] S2. When the fish top retrieval device is down, when the fish top retrieval device is not out of the surface casing, the tension claw 7 on the device will be constrained by the surface casing, and the tension claw 7 will slide down close to the inner wall of the surface casing;

[0058] S3. When the fish top retrieval device goes down out of the surface casing, the tension claw 7 on the device will slide down close to the inner wall of the open hole section;

[0059] S4. The fish top retrieval device continues to move downward, and the fingers of the tension claw 7 are evenly distributed around the circumference, and the fish top can be detected in all directions.

[0060] S5. When the fish top retrieval device goes down to the top depth of the fish, continue to go down straight so that the tension claw 7 is inserted into the lower part of the top of the fish, at this time the fish top retrieval device is blocked, the hanging weight is reduced;

[0061] S6. Maintain a certain pressure on the top of the fish, and then start to cast a ball to suppress the top of the fish to retrieve the device. The cylinder sleeve 4 of the device moves downward, and the tension claw 7 is retracted. The severely deviated top of the fish will be pulled back and forth with the recovery of the tension claw 7;

[0062] S7. Run a small-sized tubing or drill pipe string through the fish top and into the casing, thereby fixing the fish top and lifting the fish top retrieval device;

[0063] S8. Perform subsequent casing tie-back operations.

[0064] The fish top retrieval device comprises a coupling 1, a straightening body 2, a center tube 3, a liquid cylinder sleeve 4, a sealing ring 5, a steel ball 6, and a tension claw 7; the coupling 1 is sleeved on the top of the straightening body 2, the center tube 3 is arranged inside the straightening body 2, the liquid cylinder sleeve 4 is sleeved on the lower part of the straightening body 2, and a plurality of tension claws 7 are inserted into the bottom of the straightening body 2.

[0065] The centralizing body 2 is threadedly connected to the coupling 1 .

[0066] A sealing ring 5 is provided between the lower part of the centralizing body 2 and the cylinder sleeve 4.

[0067] The inner diameter of the cylinder sleeve 4 is larger than the outer diameter of the sealing ring 5 .

[0068] The inner diameter of the sealing ring 5 is larger than the outer diameter of the central tube 3 .

[0069] The minimum cross-sectional dimension of the centralizing body 2 is larger than the outer diameter of the central tube 3 .

[0070] The fingers of the tension claws 7 are evenly distributed along the circumference, and each tension claw 7 includes a straight line segment inserted into the tension claw 7, an arc segment, and a straight line segment to be used.

[0071] The tension claw 7 is made of an elastic steel bar with a diameter of 10 mm.

[0072] A steel ball 6 is arranged inside the central tube 3 .

[0073] The diameter of the steel ball 6 is smaller than the inner diameter of the central tube 3 .

[0074] A circular boss is disposed on the outer circumference of the central tube 3 , and the bottom of the circular boss is located on the upper part of the boss of the cylinder sleeve 4 .

[0075] A limiting structure is provided inside the cylinder sleeve 4 , and the limiting structure matches with the top of the circular boss of the central tube 3 .

[0076] The coupling 1, the centralizing body 2, the center tube 3, the cylinder sleeve 4 and the steel ball 6 are made of No. 45 steel.

[0077] The sealing ring 5 is made of rubber.

[0078] The fish top is the top of the drill bit, drilling tools and casing that falls to the bottom of the well during the drilling process.

[0079] An overflow hole is arranged at the lower part of the circular boss.

[0080] The inner wall of the central tube 3 is provided with a convex edge, and a steel ball 6 is provided on the convex edge.

[0081] The ball throwing and pressing in step S6 refers to throwing a steel ball 6 into the fish top retrieval device, and the steel ball 6 falls on the convex edge of the inner wall of the central tube 3 to form a seal; then water is injected into the central tube 3 of the fish top retrieval device, and the water will flow out from the overflow hole. Under the action of water pressure, the limiting structure of the liquid cylinder sleeve 4 will drive the liquid cylinder sleeve 4 downward.

[0082] Example 2

[0083] like Figure 2 As shown, this embodiment provides a fish top retrieval device, including a coupling 1, a straightening body 2, a center tube 3, a liquid cylinder sleeve 4, a sealing ring 5, a steel ball 6, and a tension claw 7; the coupling 1 is sleeved on the top of the straightening body 2, the center tube 3 is arranged inside the straightening body 2, the liquid cylinder sleeve 4 is sleeved on the lower part of the straightening body 2, and a plurality of tension claws 7 are inserted into the bottom of the straightening body 2.

[0084] The coupling 1 can be connected to the oil pipe string, and the centralizing body 2 can make the fish top retrieval device be located at the center line position of the wellbore;

[0085] The fingers of the tension claw 7 are evenly distributed along the circumference, and each tension claw 7 includes a straight segment inserted into the tension claw 7, an arc segment, and a straight segment to be used; one end of the straight segment that can be inserted into the tension claw 7 is inserted into the bottom of the central tube 3 of the eccentric sleeve catcher and welded to the body of the fish top retrieval device. The tension claw 7 uses an elastic steel bar with a diameter of 10 mm and is evenly distributed around the circumference. The lower part of the tension claw 7 has a certain rigidity and elasticity, which can be used to catch fallen fish;

[0086] Put the steel ball 6 into the fish top retrieval device, and the steel ball 6 falls on the convex edge of the inner wall of the center tube 3 to form a seal; then inject water into the center tube 3 of the fish top retrieval device, and the water will flow out from the overflow hole. Under the action of water pressure, the limit structure of the cylinder sleeve 4 will drive the cylinder sleeve 4 downward. After the steel ball 6 is put in, the oil pipe is pressed. Under the action of the hydraulic pressure, the fish top retrieval device starts to start, the cylinder sleeve 4 moves downward, and the external tension claws are retracted to the inside, so as to use the tension claws to pull back the eccentric fish. When the cylinder sleeve moves downward to the bottom dead center, it stops moving downward, and the action ends.

[0087] Example 3

[0088] like Figure 2 As shown, this embodiment provides a fish top retrieval device, including a coupling 1, a straightening body 2, a center tube 3, a liquid cylinder sleeve 4, a sealing ring 5, a steel ball 6, and a tension claw 7; the coupling 1 is sleeved on the top of the straightening body 2, the center tube 3 is arranged inside the straightening body 2, the liquid cylinder sleeve 4 is sleeved on the lower part of the straightening body 2, and a plurality of tension claws 7 are inserted into the bottom of the straightening body 2.

[0089] A method for fish top retrieval includes:

[0090] 1. Slowly lower the fish top retrieval device through the oil pipe of the righting body 2;

[0091] 2. If Figure 4 When the fish top retrieval device is moving downward, when the fish top retrieval device has not left the surface casing, the tension claw 7 will be constrained by the surface casing, and the tension claw 7 will slide downward closely against the inner wall of the surface casing;

[0092] 3. Such as Figure 5 When the fish top retrieval device descends out of the surface casing, the tension claw 7 will slide downward close to the inner wall of the open hole section;

[0093] 4. The fish top retrieval device continues to move downward. Since the fingers of the tension claw 7 are evenly distributed around the circumference, the fish top can be detected in all directions.

[0094] 5. As Figure 6 When the fish top retrieval device descends to the fish top depth, it continues to descend until the tension claw is inserted into the lower fish top (that is, inserted into the casing). At this time, the hanging weight of the pipe string will be significantly reduced due to the resistance;

[0095] 6. Such as Figure 7 , keep a certain pressure on the fish top, then start to throw the ball to suppress it, the cylinder sleeve 4 moves downward, and the tension claws 7 are retracted. The seriously deviated casing will be pulled back as the tension claws 7 are retracted;

[0096] 7. Such as Figure 8 , run a small size tubing or drill string, pass the fish top and enter the casing, thereby fixing the fish top and lifting the fish top retrieval device (such as Fig. 9 );

[0097] 8. Carry out subsequent casing tie-back operations.

[0098] The above contents are further detailed descriptions of the present invention in combination with specific preferred technical solutions, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as belonging to the protection of the present invention.

Claims

1. A method for retrieving a fish top, characterized in that: The steps include: S1. Slowly lower the fish top retrieval device into the oil pipe; S2. When the fish top retrieval device is downward, when the fish top retrieval device is not out of the surface casing, the tension claw (7) on the device will be constrained by the surface casing, and the tension claw (7) will slide down close to the inner wall of the surface casing; S3. When the fish top retrieval device descends out of the surface casing, the tension claw (7) on the device will slide down close to the inner wall of the open hole section; S4. The fish top retrieval device continues to move downward, and the fingers of the tension claw (7) are evenly distributed around the circumference, and the fish top can be detected in all directions; S5. When the fish top retrieval device descends to the top depth of the fish, it continues to descend until the tension claw (7) is inserted into the lower part of the top of the fish, at which time the fish top retrieval device is subjected to resistance and the hanging weight is reduced; S6. Maintain a certain pressure on the top of the fish, and then start to cast a ball to suppress the top of the fish to retrieve the device. The cylinder sleeve (4) of the device moves downward, and the tension claw (7) is retracted. The severely deviated top of the fish will be pulled back with the recovery of the tension claw (7); S7. Run a small-sized tubing or drill pipe string through the fish top and into the casing, thereby fixing the fish top and lifting the fish top retrieval device; S8. Perform subsequent casing tie-back operations; The fish top retrieval device comprises a coupling (1), a straightening body (2), a center tube (3), a liquid cylinder sleeve (4), a sealing ring (5), a steel ball (6), and a tension claw (7); the coupling (1) is sleeved on the top of the straightening body (2), the center tube (3) is provided inside the straightening body (2), the lower part of the center tube (3) is sleeved with a liquid cylinder sleeve, and a plurality of tension claws are inserted into the bottom of the center tube (3); the fingers of the plurality of tension claws (7) are evenly distributed along the circumference, and each tension claw (7) comprises a fixed straight line segment, a circular arc segment, and a straight line grabbing segment; The outer circumference of the central tube (3) is provided with a circular boss, the bottom of which is located at the upper part of the boss of the cylinder sleeve (4); An overflow hole is provided at the lower part of the circular boss; The inner wall of the central tube (3) is provided with a convex edge, and a steel ball (6) is provided on the convex edge.

2. A method for retrieving fish tops according to claim 1, characterized in that: The centralizing body (2) is threadedly connected to the coupling (1).

3. A method for retrieving fish tops according to claim 1, characterized in that: A sealing ring (5) is provided between the lower part of the central tube (3) and the cylinder sleeve (4).

4. A method for retrieving fish tops according to claim 3, characterized in that: The inner diameter of the cylinder sleeve (4) is greater than the outer diameter of the sealing ring (5).

5. A method for retrieving fish tops according to claim 3, characterized in that: The inner diameter of the sealing ring (5) is greater than the outer diameter of the central tube (3).

6. A method for retrieving fish tops according to claim 1, characterized in that: The minimum cross-sectional dimension of the centralizing body (2) is greater than the outer diameter of the central tube (3).

7. A method for retrieving fish tops according to claim 1, characterized in that: The tension claw (7) is made of an elastic steel bar with a diameter of 10 mm.

8. A method for retrieving fish tops according to claim 1, characterized in that: A steel ball (6) is arranged inside the central tube (3).

9. A method for retrieving fish tops according to claim 8, characterized in that: The diameter of the steel ball (6) is smaller than the inner diameter of the central tube (3).

10. A method for retrieving a fish top according to claim 1, characterized in that: A limiting structure is provided on the inner side of the cylinder sleeve (4), and the limiting structure cooperates with the top of the circular boss of the central tube (3).

11. The method for retrieving fish tops according to claim 5, characterized in that: The coupling (1), the centralizing body (2), the center tube (3), the cylinder sleeve (4), and the steel ball (6) are made of No. 45 steel.

12. A method for retrieving a fish top according to claim 1, characterized in that: The sealing ring (5) is made of rubber.

13. A method for retrieving a fish top according to claim 1, characterized in that: The fish top is the top of the casing that falls to the bottom of the well during the drilling process.

14. A method for retrieving a fish top according to claim 1, characterized in that: The ball throwing and pressing in step S6 refers to throwing the steel ball (6) into the fish top retrieval device. The steel ball (6) falls on the convex edge of the inner wall of the central tube (3) to form a seal; then water is injected into the central tube (3) of the fish top retrieval device, and the water flows out from the overflow hole. Under the action of the water pressure, the boss of the cylinder sleeve (4) drives the cylinder sleeve (4) downward.

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