A repeatable set and release compression packer and method of use

Abstract

The application discloses a layered packer capable of repeated setting and unsetting and a method thereof, which comprises an upper joint, unsetting shear pins, a forward balance piston A, a central pipe, a well washing sleeve, a reverse balance piston A, a forward balance piston B, a reverse balance piston B, a sealing ring, a snap spring, setting shear pins, a stop ring, a piston, a safety lock block, an unsetting piston cylinder, a connecting rod, an unsetting piston, a rubber cylinder seat, a rubber cylinder, a spacer ring, a rubber cylinder inner tube, a rubber cylinder pressing ring, a sealing ring, a pressure transmission pipe, a setting piston, a sealing cylinder, a spring, a setting piston cylinder, a safety shear pin, a sealing seat and the like. The packer provided by the application does not need to be additionally provided with a reverse well washing channel, and after unsetting, injection liquid can pass through an unsetting pressure transmission hole to perform reverse well washing operation. When the downhole packer cannot realize reverse well washing due to complex downhole conditions, the application can also directly pull up the central pipe by using the tubing above the upper joint, cut the unsetting shear pins, and make the liquid in the high-pressure cavity release pressure to the tubing through the setting pressure release holes on the central pipe, so that the packer is unsetting.

Description

Technical Field

[0001] This invention relates to a packer used in the field of oil extraction, and more particularly to a re-setting, unsetting, and compression packer and its method of use. Background Technology

[0002] The Shengli low-permeability reservoir has become a crucial area for stabilizing and increasing oil production. The reservoir is characterized by low permeability and deep burial. Layered water injection wells are characterized by high injection pressure and high temperature, placing demands on packers to withstand these high temperatures and pressures. The combined physical and chemical interactions of injected water with formation fluids and rock structure lead to rapid reservoir blockage, rapid pressure rise, and a shortened effective water injection cycle. To restore the reservoir's water absorption capacity, the main unblocking measure is acidizing chemical unblocking. This approach requires retrieving the original water injection tubing and then running a layered acidizing tubing for layered acidizing, resulting in a long well-occupancy period and high costs. To address this issue, this invention develops a re-setting and unsetting packer that meets the above requirements. A single well run allows for successful control of either layered water injection or layered acidizing through repeated setting and unsetting actions, reducing operating costs and shortening the well-occupancy period.

[0003] In the prior art, CN211924128U discloses a piston-type large-diameter hydraulic retrievable packer, belonging to the technical field of downhole tools for oil and gas wells. It consists of a central tube, an anchoring mechanism, a sealing mechanism, a setting and locking mechanism, and a releasing mechanism. The anchoring mechanism is mounted on the outer circumference of the central tube, the sealing mechanism is mounted on the central tube below the anchoring mechanism, and the setting and locking mechanism is mounted on the central tube below the sealing mechanism. The setting and locking mechanism is connected to the releasing mechanism via a connecting sleeve. This packer, through its dual-piston setting structure, effectively solves the problems of insufficient setting force and unstable setting performance inherent in existing packers using a single-piston method. The packer is easy to recover, reusable, and facilitates subsequent wellbore maintenance and modification, making it highly suitable for downhole operations in oil and gas wells.

[0004] CN213331008U discloses a mechanical self-testing packer, which adds a set of glue-filling tubes to the traditional packer, and installs a fixed sleeve and a connecting sleeve between the upper and lower glue-filling tubes; the sliding spline fixed to the lower end of the upper connector and the sliding key groove on the inner wall of the fixed sleeve form a sliding pair, which can transmit torque; the connecting sleeve is machined with a pressure-transmitting hole for connecting the central channel 20 and the annular space inside the casing; during operation, the casing leak detection function can be realized by using any ball seat of the same size connected to the lower connector; it is also easy to unseal, and can be reused when multiple leak tests of the casing are required; the structure is simple and can be used interchangeably with some parts of the RTTS packer; it can be reused multiple times to sequentially test multiple parts of the casing for leaks and cross-contamination; only the ball seat needs to be connected to provide a detailed interpretation of the packer setting situation, and determine whether the incomplete setting is due to incomplete bonding or casing leakage; when the ball seat is not connected, it can be used as an ordinary packer, and has strong versatility.

[0005] CN113047805A discloses a self-sealing oilfield packer for oilfield development, relating to the field of oilfield packers. This self-sealing oilfield packer includes a central tube and an upper sealing element. The upper wall of the central tube has evenly distributed grooves. A sliding sleeve is slidably disposed on the inner circumference of the upper part of the lower outer tube. The upper part of the sliding sleeve is slidably disposed on the inner circumference of the lower part of the upper outer tube. A limit groove is provided on the inner circumference of the upper end of the sliding sleeve. A rubber sleeve is disposed on the outer circumference of the upper part of the sliding sleeve. A through groove is evenly distributed on the bottom of the lower outer tube. A third spring is evenly distributed on the outer circumference of the bottom of the central tube. A threaded post is fixedly connected to the top of the upper sealing element, and a sealing pin is fixedly connected to the lower end of the upper sealing element. The outer diameter of the middle part of the upper sealing element is less than or equal to the inner diameter of the central tube. This fixed design of the packer ensures the rubber sleeve can be used effectively, preventing the rubber sleeve from losing its sealing performance or deforming due to pressure deformation. The rubber sleeve can be reused, making this design worthy of widespread promotion.

[0006] CN113356787A discloses a high-temperature and high-pressure resistant retrievable downhole packer, including a central tube; a power unit including a first housing, cylinder, piston, sliding sleeve, and control lines; a first slip portion capable of supporting the inner wall of the well casing under the downward pressure of the sliding sleeve, and capable of moving downward synchronously with the downward movement of the sliding sleeve; a packer portion including a packer sleeve, a high-temperature resistant sleeve, and a pad, sleeved on the central tube and located below the first slip portion; a second slip portion capable of supporting the inner wall of the well casing under the downward pressure of the sliding sleeve; a second housing fixed to the bottom end of the central tube and fixedly connected to the bottom end of the first slip portion. The packer provided by this invention has a simple structure, employs two clamping connections to improve structural stability, and has stronger high-pressure resistance; the high-temperature resistant sleeve enhances high-temperature resistance; this invention overcomes the problems of complex packer structures, difficult setting and unsealing, long cycles, and high operating costs in the prior art.

[0007] However, the packers mentioned above cannot achieve efficient repeated setting and unsealing, and also have the problem of incomplete unsealing. Summary of the Invention

[0008] The purpose of this invention is to provide a re-setting and unsetting layered packer tool, relating to the fields of layered acidizing and layered water injection technology. This packer uses a high-pressure setting method during the initial setting, and can be re-setting under low pressure after normal operation. After setting, the packer prevents automatic unsetting based on dynamic balance, fundamentally eliminating the harm caused by the creep of the upper tubing string to the lower packer sleeve under axial load, axial vibration load, water injection pressure, and temperature fluctuations. During normal operation, the sleeve remains permanently compressed under the action of the connecting rod, setting piston, and spring. During well flushing, the sleeve overcomes the spring force under the action of the unsetting piston to depressurize and unseal, allowing for large-channel well flushing. When resuming normal operation, the sleeve can be re-setting under low pressure.

[0009] To achieve the above objectives, the present invention adopts the following technical solution: the reusable set-and-unseal layered packer tool mainly consists of an upper connector, an unsealable shear pin, a forward balancing piston A, a central tube, a well-washing sleeve, a reverse balancing piston A, a forward balancing piston B, a reverse balancing piston B, a sealing ring, a snap ring, a set-and-unseal shear pin, a retaining ring, a piston, a safety locking block, an unsealable piston cylinder, a connecting rod, an unsealable piston, a rubber sleeve seat, a rubber sleeve, a spacer ring, a rubber sleeve inner tube, a rubber sleeve pressure ring, a sealing ring, a pressure transmission tube, a set-and-unseal piston, a sealing cylinder, a spring, a set-and-unseal piston cylinder, a safety shear pin, a sealing seat, a T-shaped seal, a pressure cap, a sealing plug, and a lower connector.

[0010] The upper connector of the tubing string is connected to the central tube and the well-washing sleeve. The central tube is connected by a thread, and the upper connector and the well-washing sleeve are fixed with a release shear pin. The cavities of the central tube and the well-washing sleeve contain a forward balancing piston A, a reverse balancing piston A, a forward balancing piston B, and a reverse balancing piston B, and each balancing piston is sealed with a sealing ring.

[0011] The bottom of the central tube is threaded to the lower connector. A retaining spring is located in the middle of the central tube, which can be inserted into the groove formed by the retaining ring and piston during setting and balancing to provide a fixing function. The retaining ring and the release piston cylinder are fixed together by setting shear pins. There is a groove on the outside of the middle section of the central tube, which contains a safety locking block. The lower end of the safety locking block has a connecting rod that can move up and down. Between the release piston cylinder and the connecting rod is a release piston and a rubber sleeve seat. The rubber sleeve seat is threaded to the inner tube of the rubber sleeve. The inner tube of the rubber sleeve is fitted with a rubber sleeve, a spacer ring, and a rubber sleeve pressure ring. The lower end of the rubber sleeve pressure ring is threaded to the setting piston, and the inner cavity of the rubber sleeve pressure ring has a sealing ring. The sealing ring is threaded to the inner tube of the rubber sleeve and the pressure transmission tube.

[0012] The setting piston and setting piston cylinder are threaded together and sealed with a rubber ring. Safety shear pins secure the setting piston cylinder and sealing cylinder. A spring is installed within the cavity formed by the connecting rod, pressure transmission tube, and sealing cylinder. The lower end of the connecting rod is threaded to the sealing seat, which is threaded to the pressure cap. The sealing seat and pressure cap form a T-shaped hole for housing a T-shaped seal. The bottom end of the sealing cylinder is threaded to the sealing plug.

[0013] The packer provided by this invention does not require a separate backwashing channel. After unsealing, the injected fluid can be used for backwashing operations through the unsealing pressure transmission hole. When the downhole packer encounters complex downhole conditions and cannot achieve backwashing, this invention can also use the tubing above the upper connector to directly lift the central tube, cut the unsealing shear pin, and release the pressure of the liquid in the high-pressure chamber into the tubing through the setting and pressure relief hole on the central tube, thereby achieving packer unsealing. Attached Figure Description

[0014] Appendix Figure 1 This is a schematic diagram of the structure of a re-setting, unsealing, and layered packer tool.

[0015] In the diagram: 1-Upper connector, 2-Unsealing shear pin, 3-Forward balancing piston A, 4-Center tube, 5-Well cleaning sleeve, 6-Reverse balancing piston A, 7-Forward balancing piston B, 8-Reverse balancing piston B, 9-Sealing ring, 10-Snap ring, 11-Setting shear pin, 12-Retaining ring, 13-Piston, 14-Safety lock block, 15-Unsealing piston cylinder, 16-Connecting rod, 17-Unsealing piston, 18-Rubber sleeve seat, 19-Rubber sleeve, 20-Spacer ring, 21-Rubber sleeve inner tube, 22-Rubber sleeve pressure ring, 23-Sealing ring, 24-Pressure transmission tube, 25-Setting piston, 26-Sealing cylinder, 27-Spring, 28-Setting piston cylinder, 29-Safety shear pin, 30-Sealing seat, 31-T-type seal, 32-Pressure cap, 33-Sealing plug, 34-Lower connector Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0017] Example 1:

[0018] A certain oil well uses a layered packer that can be repeatedly set and unset. Its tools mainly consist of an upper connector, unsetting shear pin, forward balancing piston A, center tube, well washing sleeve, reverse balancing piston A, forward balancing piston B, reverse balancing piston B, sealing ring, snap ring, setting shear pin, retaining ring, piston, safety locking block, unsetting piston cylinder, connecting rod, unsetting piston, rubber sleeve seat, rubber sleeve, spacer ring, rubber sleeve inner tube, rubber sleeve pressure ring, sealing ring, pressure transmission tube, setting piston, sealing cylinder, spring, setting piston cylinder, safety shear pin, sealing seat, T-type seal, pressure cap, sealing plug, and lower connector.

[0019] The upper connector of the tubing string is connected to the central tube and the well-washing sleeve. The central tube is connected by a thread, and the upper connector and the well-washing sleeve are fixed with a release shear pin. The cavities of the central tube and the well-washing sleeve contain a forward balancing piston A, a reverse balancing piston A, a forward balancing piston B, and a reverse balancing piston B, and each balancing piston is sealed with a sealing ring.

[0020] The bottom of the central tube is threaded to the lower connector. A retaining spring is located in the middle of the central tube, which can be inserted into the groove formed by the retaining ring and piston during setting and balancing to provide a fixing function. The retaining ring and the release piston cylinder are fixed together by setting shear pins. There is a groove on the outside of the middle section of the central tube, which contains a safety locking block. The lower end of the safety locking block has a connecting rod that can move up and down. Between the release piston cylinder and the connecting rod is a release piston and a rubber sleeve seat. The rubber sleeve seat is threaded to the inner tube of the rubber sleeve. The inner tube of the rubber sleeve is fitted with a rubber sleeve, a spacer ring, and a rubber sleeve pressure ring. The lower end of the rubber sleeve pressure ring is threaded to the setting piston, and the inner cavity of the rubber sleeve pressure ring has a sealing ring. The sealing ring is threaded to the inner tube of the rubber sleeve and the pressure transmission tube.

[0021] The setting piston and setting piston cylinder are threaded together and sealed with a rubber ring. Safety shear pins secure the setting piston cylinder and sealing cylinder. A spring is installed within the cavity formed by the connecting rod, pressure transmission tube, and sealing cylinder. The lower end of the connecting rod is threaded to the sealing seat, which is threaded to the pressure cap. The sealing seat and pressure cap form a T-shaped hole for housing a T-shaped seal. The bottom end of the sealing cylinder is threaded to the sealing plug.

[0022] Example 2:

[0023] The basic process for using the packer described above in an oil well is as follows:

[0024] I. Sealing

[0025] 1. Begin sealing

[0026] The power fluid acts on the setting piston 25 through the setting seal pressure relief hole and the inlet hole 1, and the pressure reaches about 8MPa. The safety shear pin 29 is cut off, and the setting piston 25 drives the setting piston cylinder 28 and the rubber sleeve pressure ring 22 to move to the left to compress the rubber sleeve and start the setting process.

[0027] 2. Sealing force balance

[0028] The power fluid acts on the piston 13 through the left inlet hole 2, causing the retaining ring 12 to cut the setting shear pin 11 and move to the left. It is limited by the central tube 4. At the same time, the retaining ring 10 is embedded in the groove formed by the retaining ring 12 and the piston 13 to prevent them from moving to the right. The safety lock block 14 is released, preparing for the connecting rod 16 to move to the right.

[0029] The forward balancing pistons A3 and B7 move to the left, and the force is applied to the well casing 5 to achieve a balancing effect. This is used to balance the downward thrust generated during the setting process and prevent the packer from automatically releasing during the setting process.

[0030] The packer is set when the pressure reaches 16-20 MPa.

[0031] 3. Tighten the seal

[0032] After the oil pipe is depressurized, the connecting rod 16, sealing seat 30, T-seal 31, and pressure cap 32 move to the right under the elastic force of the spring 27. The T-seal 31 moves to the right into the inner hole of the sealing plug 33 to achieve a seal, ensuring that the pressure in the packer setting chamber [enclosed by the connecting rod 16, inner tube 21 of the rubber sleeve, setting piston 25, sealing cylinder 26, sealing seat 30, T-seal 31, pressure cap 32, and sealing plug 33] is always in a high-pressure state, so that the packer rubber sleeve is in a permanent compression sealing state.

[0033] II. Repeated sealing and unsealing

[0034] 1. Unsealing the backwash well

[0035] When backwashing is required, the power fluid acts on the unsealing piston 17 through the inlet 5 of the unsealing piston cylinder 15, driving the connecting rod 16, sealing seat 30, T-shaped seal 31, and pressure cap 32 to move to the left against the spring force. After the T-shaped seal 31 disengages from the inner sealing surface of the sealing plug 33, the liquid in the high-pressure chamber is depressurized into the tubing through the setting and pressure relief hole of the central tube 4, thereby unsealing the packer, establishing a well-washing channel, and ensuring smooth well washing.

[0036] 2. Repeated sealing

[0037] The pressure is restored from the oil pipe, and the liquid still acts on the setting piston 25 through the setting and pressure relief hole of the central tube (4) and the inlet hole 1 on the pressure transmission tube 24, compressing the rubber sleeve to achieve setting. After depressurization, the connecting rod 16, sealing seat 30, T-type seal 31, and pressure cap 32 move to the right into the inner sealing hole of the sealing plug 33 under the elastic force of the spring 27, achieving high-pressure liquid sealing and ensuring that the packer is always in a sealed state.

[0038] III. Unsealing the tubing column

[0039] 1. Unsealing of backwash well.

[0040] The steps are the same as above; after the packer is released, simply lift the tubing string.

[0041] 2. Lifting the tubing string to release the seal

[0042] If the backwash well is blocked, the central tube 4 can be pulled up directly through the tubing above the upper connector 1. After cutting the unsealing shear pin 2, the central tube 4 moves upward, causing the T-type seal 31 to move to the left. When the T-type seal 31 moves out of the inner sealing hole of the sealing plug 33, the liquid in the high-pressure chamber is depressurized into the tubing through the setting and pressure relief hole on the central tube 4, thus releasing the packer. Then, continue pulling up to retrieve the entire tubing string.

[0043] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A re-setting and desealable layered packer, characterized in that: Includes the upper connector (1), forward balance piston A (3), central pipe (4), well washing sleeve (5), reverse balance piston A (6), forward balance piston B (7), and reverse balance piston B (8). The upper connector (1) is connected to the central pipe (4) and the well washing sleeve (5). The cavity of the central pipe (4) and the well washing sleeve (5) contains the positive balance piston A (3), the reverse balance piston A (6), the positive balance piston B (7), and the reverse balance piston B (8). It also includes a lower connector (34), a snap ring (10), a setting screw (11), a retaining ring (12), a piston, and a release piston cylinder (15). The bottom of the central tube (4) is threadedly connected to the lower connector (34). The snap ring (10) is disposed on the central tube (4). The retaining ring (12) and the release piston cylinder (15) are fixed by the setting screw (11). The central tube (4) has a slot on the outside of the middle section, and a safety lock block (14) is provided inside. The lower end of the safety lock block (14) is provided with a connecting rod (16) that can move up and down. A release piston (17) and a rubber sleeve seat (18) are provided between the release piston cylinder (15) and the connecting rod (16). The rubber sleeve seat (18) is connected to the rubber sleeve inner tube (21) by threads. The rubber sleeve (19), spacer ring (20) and rubber sleeve pressure ring (22) are sleeved on the rubber sleeve inner tube (21). The lower end of the rubber sleeve pressure ring (22) is threaded to the setting piston (25). A sealing ring (23) is provided in the inner cavity of the rubber sleeve pressure ring (22). The sealing ring (23) is connected to the rubber sleeve inner tube (21) and the pressure transmission tube (24) by threads. The setting piston (25) and the setting piston cylinder (28) are connected by threads and sealed with rubber rings. The setting piston cylinder (28) and the sealing cylinder (26) are fixed by safety shear pins (29). A spring (27) is provided in the cavity formed by the connecting rod (16) and the sealing cylinder (26). The lower end of the connecting rod (16) is connected to the sealing seat (30) by threads. The sealing seat (30) is connected to the pressure cap (32) by threads. The sealing seat (30) and the pressure cap (32) form a T-shaped hole for placing the T-shaped seal (31). The bottom end of the sealing cylinder (26) is connected to the sealing plug (33) by threads. The upper connector (1) is connected to the central pipe (4) and the well cleaning sleeve (5) by means of threads; Use the unsealing shear pin (2) to fix the upper connector (1) and the well casing (5).

2. The resealable and desealable layered packer as described in claim 1, characterized in that: The forward balancing piston A (3), the reverse balancing piston A (6), the forward balancing piston B (7), and the reverse balancing piston B (8) are sealed with sealing rings (9).

3. A method of using a resealable and desealable layered packer as described in any one of claims 1-2, characterized in that, Includes the following steps: I. Sealing; ① Begin sealing the seal; The power fluid acts on the setting piston (25) through the first inlet hole from the setting seal pressure relief hole. When the pressure reaches the first pressure, the safety shear pin (29) is cut off. The setting piston (25) drives the setting piston cylinder (28) and the rubber sleeve pressure ring (22) to move to the left to compress the rubber sleeve and start setting. ② The sealing force is balanced; The power fluid acts on the piston (13) through the second inlet hole on the left, causing the retaining ring (12) to cut the setting shear pin (11) and move to the left. It is limited by the central tube (4). At the same time, the snap ring (10) is embedded in the groove formed by the retaining ring (12) and the piston (13) to prevent them from moving to the right. The safety lock block (14) is released, preparing for the connecting rod (16) to move to the right. The positive balancing piston A (3) and the positive balancing piston B (7) move to the left, and the force is applied to the well casing (5) to play a balancing role. This is used to balance the downward thrust generated during the setting process and prevent the packer from automatically releasing during the setting process. The packer is set when the pressure reaches the second pressure, which is greater than the first pressure. ③ Tighten and seal; After the oil pipe is depressurized, the connecting rod (16), sealing seat (30), T-type seal (31), and pressure cap (32) move to the right under the elastic force of the spring (27). The T-type seal (31) moves to the right into the inner hole of the sealing plug (33) to achieve sealing, ensuring that the pressure in the packer seat cavity is always in a high-pressure state, so that the packer rubber sleeve is in a permanent compression sealing state. II. Repeated sealing and unsealing; ① Unsealing of backwash wells; When backwashing is required, the power fluid acts on the unsealing piston (17) through the fifth inlet hole of the unsealing piston cylinder (15), driving the connecting rod (16), sealing seat (30), T-type seal (31), and pressure cap (32) to move to the left against the spring force. After the T-type seal (31) is separated from the inner sealing surface of the sealing plug (33), the liquid in the high-pressure chamber is depressurized into the tubing through the seat pressure relief hole of the central tube (4), thereby realizing the unsealing of the packer, establishing a well washing channel, and ensuring smooth well washing. ② Repeated sealing; Pressurize again from the oil pipe, and the liquid still acts on the setting piston (25) through the first liquid inlet on the pressure transmission pipe (24) from the setting and pressure relief hole of the central pipe (4), compressing the rubber sleeve to achieve setting. After depressurization, the connecting rod (16), sealing seat (30), T-type seal (31), and pressure cap (32) move to the right into the inner sealing hole of the sealing plug (33) under the elastic force of the spring (27), achieving high-pressure liquid sealing and ensuring that the packer is always in a sealed state. III. Unseal the tubing column; ① Unsealing of backwash wells; The procedure is the same as that for reverse washing well unsealing; after the packer is unsealed, the tubing string is pulled up directly. ② Lifting the tubing string to release the seal If the backwash well is blocked, the central tube (4) is lifted directly through the tubing above the upper connector (1). After the unsealing shear pin (2) is cut off, the central tube (4) moves upward, causing the T-type seal (31) to move to the left. When the T-type seal (31) moves out of the inner sealing hole of the sealing plug (33), the liquid in the high-pressure chamber is depressurized into the tubing through the setting and pressure relief hole on the central tube (4), thus achieving packer unsealing. Then, the entire tubing string is lifted out.

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