Lifting type double-sealing balance valve and method for assisting in dragging pipe column fracturing packer to unblock

Abstract

The invention relates to the technical field of oil field fracturing tools, in particular to a lifting type double-seal balance valve and an auxiliary dragging tubular column fracturing packer deblocking method.The lifting type double-seal balance valve comprises an upper connector, a guide seat cap, a guide seat, a lower connector, a guide movable connector, a sealing bush, a steel ball baffle and a steel ball, and the steel ball is arranged in an inner hole of a ball seat frustum; a steel ball baffle is arranged on the inner side of the upper connector corresponding to the upper side of the steel ball, and the outer side of the lower portion of the upper connector is fixedly connected with the inner side of the upper portion of the guide movable connector. Switching between an opening position and a closing position can be achieved by lifting and lowering the fracturing pipe column, when the lifting and lowering type double-seal balance valve is located at the opening position, the bottom sealing packer is communicated with the upper fracturing pipe column in the vertical direction, the pressure of the upper portion and the lower portion of the bottom sealing packer is balanced, and therefore when the fracturing pipe column is lifted to unseal the bottom sealing packer, the bottom sealing packer can be separated from the bottom sealing packer. The rubber sleeve of the bottom seal packer cannot be damaged due to the pressure difference between the upper portion and the lower portion of the bottom seal packer, and the service life of the bottom seal packer is prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of oilfield fracturing tools, in particular to a lifting and releasing double-sealed balancing valve and an auxiliary dragging pipe column fracturing packer unsealing method. Background Art

[0002] The dragging string fracturing process uses a double-seal layer-stuck method to accurately and fully transform the target reservoir. It is a fracturing technology commonly used in the repeated transformation of old horizontal wells to tap the potential of residual oil. The dragging string is usually sealed with a compression packer on the top and a mechanical packer on the bottom. After the dragging string fracturing, the pressure difference between the upper and lower formations of the bottom seal packer is different. The pressure imbalance between the upper and lower layers of the bottom seal packer and the forced lifting of the string to unseal it is easy to damage the rubber cylinder of the bottom seal packer and bring greater well control safety hazards. Therefore, it is particularly important to balance the upper and lower pressure differences of the bottom seal packer before unsealing after the dragging string. The biggest advantage of this technology is the lifting and releasing switch action, which is relatively simple to operate. The lifting string device is opened, and the upper and lower pressure balance of the bottom seal assists in completing the string unsealing. The lowering string balance device closes and blocks the lower layer segment fluid inlet channel to complete the layer-changing fracturing. Summary of the invention

[0003] The present invention provides a lifting and releasing double-sealed balancing valve and an auxiliary dragging pipe string fracturing packer unsealing method, which overcomes the shortcomings of the above-mentioned prior art and can effectively solve the problem in the existing dragging pipe string fracturing process that the rubber sleeve of the bottom seal packer is easily damaged when the upper pipe string is unsealed due to the different upper and lower pressures of the bottom seal packer after compression.

[0004] One of the technical solutions of the present invention is achieved through the following measures: a lifting and releasing double-sealed balancing valve, comprising an upper joint, a guide seat and cap, a guide seat, a lower joint, a guide movable joint, a sealing bushing, a steel ball baffle and a steel ball, a ball seat cone with a larger upper portion and a smaller lower portion is provided on the inner side of the upper joint, a steel ball is provided in the inner hole of the ball seat cone, a steel ball baffle is provided on the inner side of the upper joint corresponding to the upper side position of the steel ball, the guide movable joint is a cylindrical structure with an open upper end and a closed lower end, the lower outer side of the upper joint is fixedly connected to the upper inner side of the guide movable joint, the outer side of the upper joint corresponding to the upper side position of the guide movable joint is sleeved with a guide seat and cap that cooperates with the upper joint for sliding sealing, the lower outer side of the guide seat and cap is fixedly connected with the guide seat, the lower outer side of the guide movable joint is provided with an outer ring groove, and the outer side of the guide movable joint corresponding to the position of the outer ring groove is sleeved from the inside to the outside in sequence A sealing bushing and a lower joint are provided, and the sealing bushing and the guide movable joint are sealed and matched. The top wall of the outer ring groove abuts against the upper end of the sealing bushing, the outer side of the sealing bushing and the inner side of the lower joint are fixedly connected, the upper outer side of the lower joint and the lower inner side of the guide seat are fixedly connected, and an annular cavity is enclosed between the upper joint, the guide movable joint, the guide seat cap, the guide seat, the lower joint and the sealing bushing. A first liquid passage communicating with the annular cavity is provided on the outer wall of the guide seat, and a second liquid passage communicating with the internal channel of the guide movable joint and the annular cavity is provided on the outer wall of the guide movable joint corresponding to the lower side position of the upper joint. The upper end of the guide movable joint can abut against the lower end of the guide seat cap when the guide movable joint moves upward relative to the sealing bushing, and when the upper end of the guide movable joint abuts against the lower end of the guide seat cap, the guide movable joint is separated from the sealing bushing.

[0005] The following is a further optimization and / or improvement of one of the above invention solutions: A plurality of first mounting ring grooves may be arranged on the inner wall of the outer ring groove corresponding to the position of the sealing bushing at intervals in the upper and lower parts, and a star-shaped sealing ring is installed in each first mounting ring groove.

[0006] A second mounting ring groove may be provided on the upper end surface of the sealing bushing at the top wall position corresponding to the outer ring groove, and an O-type sealing ring is installed in the second mounting ring groove.

[0007] The lower outer side of the above-mentioned upper joint and the upper inner side of the guide movable joint can be connected together by threaded fixing, and a back-off screw is provided between the lower outer side of the upper joint and the upper inner side of the guide movable joint; the lower outer side of the guide seat cap and the upper inner side of the guide seat are connected together by threaded fixing, and a back-off screw is provided between the lower outer side of the guide seat cap and the upper inner side of the guide seat.

[0008] The upper outer side of the above-mentioned lower joint and the lower inner side of the guide seat can be connected together by threaded fixation, and a stop screw and an O-ring are provided between the upper outer side of the lower joint and the lower inner side of the guide seat; the outer side of the sealing bushing and the inner side of the lower joint are connected together by threaded fixation, and an O-ring is provided between the outer side of the sealing bushing and the inner side of the lower joint.

[0009] The second technical solution of the present invention is achieved by the following measures: a method for unsealing a fracturing packer by auxiliary dragging of a tubing string, comprising the following steps: S1: Lowering the fracturing string into the well. The fracturing string includes a safety joint, a hydraulic anchor, a top seal packer, a sandblaster, a lifting double seal balancing valve, a bottom seal packer and a guide head which are connected to the oil pipe in sequence from top to bottom. During the lowering process, the guide movable joint is separated from the sealing bushing, and the lifting double seal balancing valve is in the open position; S2: When the fracturing string reaches the target layer, continue to lower the fracturing string to make the guide movable joint go down and insert into the sealing bushing, the lifting and releasing double-sealing balancing valve is in the closed position, and then continue to lower the fracturing string to pressurize the bottom seal packer, and then implement the fracturing pumping construction; S3: After the fracturing pumping construction of the target layer is completed, the fracturing string is lifted up to separate the guide movable joint from the sealing bushing, the lifting and releasing double-sealed balancing valve is in the open position, and reverse circulation well washing is performed. Then the fracturing string is further lifted up to release the bottom seal packer, and the fracturing string is dragged to the next target layer to complete the layer change; S4: Repeat steps S2 to S3 until the multi-layer fracturing is completed.

[0010] The present invention has a reasonable structure. The present invention can switch between the open position and the closed position by lifting and lowering the fracturing string. When the lifting and releasing double-sealed balancing valve is in the closed position, the bottom seal packer is not connected to the upper fracturing string up and down. Therefore, the wellbore fluid pumped during fracturing pumping can be sprayed out from the sandblaster into the target layer, that is, the fracturing pumping construction requirements are met. When the lifting and releasing double-sealed balancing valve is in the open position, the bottom seal packer is connected to the upper fracturing string up and down, balancing the upper and lower pressures of the bottom seal packer. Therefore, when the fracturing string is lifted to unseal the bottom seal packer, the rubber cylinder of the bottom seal packer will not be damaged due to the upper and lower pressure difference of the bottom seal packer, thereby extending the service life of the bottom seal packer. In addition, the opening and closing of the lifting and releasing double-sealed balancing valve is only achieved by the mechanical action of lifting and lowering the fracturing string, and is not affected by factors such as flow rate and pressure difference. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Attached Figure 1 It is a schematic diagram of the main cross-sectional structure of the lifting and releasing double-sealed balancing valve in embodiments 1 and 2 of the present invention when it is in the closed position.

[0012] Attached Figure 2It is a schematic diagram of the main cross-sectional structure of the lifting and releasing double-sealed balancing valve in embodiments 1 and 2 of the present invention when it is in the open position.

[0013] Attached Figure 3 It is a schematic diagram of the structure of the fracturing string in Embodiments 1 and 2 of the present invention.

[0014] The codes in the accompanying drawings are: 1 is an upper joint, 2 is a guide seat and cap, 3 is a guide seat, 4 is a lower joint, 5 is a guide movable joint, 6 is a sealing bushing, 7 is a steel ball baffle, 8 is a steel ball, 9 is a ball seat cone, 10 is an annulus cavity, 11 is a first liquid passage, 12 is a second liquid passage, 13 is a star-shaped sealing ring, 14 is an O-ring, 15 is a stop screw, 16 is an oil pipe, 17 is a safety joint, 18 is a hydraulic anchor, 19 is a top seal packer, 20 is a sandblaster, 21 is a lift-and-release double-seal balancing valve, 22 is a bottom seal packer, and 23 is a guide head. DETAILED DESCRIPTION

[0015] The present invention is not limited by the following embodiments, and specific implementation methods can be determined based on the technical solution of the present invention and actual conditions.

[0016] In the present invention, for the convenience of description, the relative position relationship of each component is described according to the attached Figure 1 The positional relationships such as front, back, top, bottom, left, and right are described according to the layout directions of the drawings in the specification.

[0017] The present invention will be further described below in conjunction with embodiments and drawings: As attached Figure 1-3As shown, the lifting and releasing double-sealed balancing valve comprises an upper joint 1, a guide seat and cap 2, a guide seat 3, a lower joint 4, a guide movable joint 5, a sealing bushing 6, a steel ball baffle 7 and a steel ball 8. A ball seat cone 9 with a larger upper part and a smaller lower part is provided on the inner side of the upper joint 1. A steel ball 8 is provided in the inner hole of the ball seat cone 9. A steel ball baffle 7 is provided on the inner side of the upper joint 1 corresponding to the upper side of the steel ball 8. The guide movable joint 5 is a cylindrical structure with an open upper end and a closed lower end. The lower outer side of the upper joint 1 is fixedly connected to the upper inner side of the guide movable joint 5. The outer side of the upper joint 1 corresponding to the upper side of the guide movable joint 5 is sleeved with a guide seat and cap 2 that cooperates with the upper joint 1 for sliding sealing. The lower outer side of the guide seat and cap 2 is fixedly connected with the guide seat 3. The lower outer side of the guide movable joint 5 is provided with an outer ring groove. The outer side of the guide movable joint 5 corresponding to the position of the outer ring groove is sleeved with a sealing bushing 6 and the lower joint 4 in sequence from the inside to the outside. The sleeve 6 and the guide movable joint 5 are sealed and matched, the top wall of the outer ring groove and the upper end of the sealing bushing 6 are abutted, the outer side of the sealing bushing 6 and the inner side of the lower joint 4 are fixedly connected, the upper outer side of the lower joint 4 and the lower inner side of the guide seat 3 are fixedly connected, and an annular cavity 10 is enclosed between the upper joint 1, the guide movable joint 5, the guide seat and cap 2, the guide seat 3, the lower joint 4 and the sealing bushing 6. A first liquid passage 11 connected to the annular cavity 10 is provided on the outer wall of the guide seat 3, and a second liquid passage 12 connecting the internal channel of the guide movable joint 5 and the annular cavity 10 is provided on the outer wall of the guide movable joint 5 corresponding to the lower side position of the upper joint 1. The upper end of the guide movable joint 5 can abut against the lower end of the guide seat and cap 2 when the guide movable joint 5 moves upward relative to the sealing bushing 6, and when the upper end of the guide movable joint 5 abuts against the lower end of the guide seat and cap 2, the guide movable joint 5 is separated from the sealing bushing 6.

[0018] When in use, the safety joint 17, hydraulic anchor 18, top seal packer 19, sandblaster 20, lifting double seal balance valve 21, bottom seal packer 22 and guide head 23 are sequentially connected in series on the oil pipe 16 from top to bottom to form a fracturing string. The upper joint 1 is fixedly connected to the sandblaster 20 through the oil pipe 16, and the lower joint 4 is fixedly connected to the bottom seal packer 22 through the oil pipe 16. Specifically, the top seal packer 19 is a Y344 packer or a K344 packer, and the bottom seal packer 22 is a TDY2 During the lowering of the fracturing string, the pipe string consisting of the upper joint 1 and the guide movable joint 5 and the pipe string consisting of the guide seat cap 2, the guide seat 3, the lower joint 4, and the sealing bushing 6 are in a pulled-apart state. At this time, the upper end of the guide movable joint 5 abuts against the lower end of the guide seat cap 2, the guide movable joint 5 is separated from the sealing bushing 6, the internal channel of the lifting and releasing double-sealed balancing valve is connected, and the lifting and releasing double-sealed balancing valve is in the open position. When the fracturing string is lowered to the target layer, the fracturing string is continuously lowered to make the guide movable joint 4 close to the target layer. The joint 5 is inserted into the sealing bushing 6 when it is lowered, and the guide movable joint 5 is sealed and connected with the sealing bushing 6, the internal channel of the lifting and releasing type double-sealed balancing valve is closed, and the lifting and releasing type double-sealed balancing valve is in the closed position, and then the fracturing string is continued to be lowered to pressurize and seal the bottom seal packer 22, and then the fracturing pumping construction is carried out; when the fracturing pumping construction of the target layer is completed, the fracturing string is lifted up to make the guide movable joint 5 move upward and separate from the sealing bushing 6, and the lifting and releasing type double-sealed balancing valve is in the open position again, and the bottom seal packer 22 is connected to the upper fracturing string. The well is connected down, and then reverse circulation well washing is carried out. During reverse circulation well washing, the workover fluid enters the interior of the lifting and releasing double-sealed balancing valve from the first liquid passage 11, and then enters the upper joint 1 through the second liquid passage 12 and pushes open the steel ball 8. The steel ball 8 is pushed upward by the workover fluid to the steel ball baffle 7. The steel ball baffle 7 has an opening. The workover fluid flows through the opening of the steel ball baffle 7 and enters the upper fracturing string. After the reverse circulation well washing is completed, the fracturing string is continued to be lifted up to unseal the bottom seal packer 22, and the fracturing string is dragged to the next target layer to complete the layer change.

[0019] The lifting and releasing type double-sealed balancing valve of the present application can be switched between the open position and the closed position by lifting and lowering the fracturing pipe string. When the lifting and releasing type double-sealed balancing valve is in the closed position, the bottom seal packer 22 is not connected with the upper fracturing pipe string up and down. Therefore, the wellbore pressure fluid pumped during fracturing pumping can be sprayed out from the sandblaster 20 into the target layer, that is, the fracturing pumping construction requirements are met. When the lifting and releasing type double-sealed balancing valve is in the open position, the bottom seal packer 22 is connected with the upper fracturing pipe string up and down, balancing the upper and lower pressures of the bottom seal packer 22. Therefore, when the fracturing pipe string is lifted to unseal the bottom seal packer 22, the rubber cylinder of the bottom seal packer 22 will not be damaged due to the upper and lower pressure difference of the bottom seal packer 22, thereby extending the service life of the bottom seal packer 22. In addition, the opening and closing of the lifting and releasing type double-sealed balancing valve is only realized by the mechanical action of lifting and lowering the fracturing pipe string, and is not affected by factors such as flow rate and pressure difference.

[0020] The above embodiments may be further optimized and / or improved according to actual needs: As attached Figure 1-2 As shown, a plurality of first mounting ring grooves are arranged at intervals from top to bottom on the inner wall of the outer ring groove corresponding to the position of the sealing bushing 6, and a star-shaped sealing ring 13 is installed in each first mounting ring groove; a second mounting ring groove is arranged on the upper end surface of the sealing bushing 6 corresponding to the top wall position of the outer ring groove, and an O-shaped sealing ring 14 is installed in the second mounting ring groove. Thus, the sealing performance between the guide movable joint 5 and the sealing bushing 6 is ensured when the two are sealed and connected. Specifically, in this embodiment, the number of the star-shaped sealing rings 13 is 7.

[0021] As attached Figure 1-2 As shown, the lower outer side of the upper joint 1 and the upper inner side of the guide movable joint 5 are connected together by threaded fixing, and a back-off screw 15 is provided between the lower outer side of the upper joint 1 and the upper inner side of the guide movable joint 5; the lower outer side of the guide seat cap 2 and the upper inner side of the guide seat 3 are connected together by threaded fixing, and a back-off screw 15 is provided between the lower outer side of the guide seat cap 2 and the upper inner side of the guide seat 3; the upper outer side of the lower joint 4 and the lower inner side of the guide seat 3 are connected together by threaded fixing, and a back-off screw 15 and an O-ring 14 are provided between the upper outer side of the lower joint 4 and the lower inner side of the guide seat 3; the outer side of the sealing bushing 6 and the inner side of the lower joint 4 are connected together by threaded fixing, and an O-ring 14 is provided between the outer side of the sealing bushing 6 and the inner side of the lower joint 4.

[0022] Embodiment 2: As shown in the attached Figure 1-3 As shown, the auxiliary dragging pipe string fracturing packer unsealing method comprises the following steps: S1: lowering the fracturing string into the well, the fracturing string includes a safety joint 17, a hydraulic anchor 18, a top seal packer 19, a sandblaster 20, a lifting double seal balancing valve 21, a bottom seal packer 22 and a guide head 23 which are connected in series on the oil pipe 16 from top to bottom. During the lowering process, the guide movable joint 5 is separated from the sealing bushing 6, and the lifting double seal balancing valve is in the open position; S2: When the fracturing string reaches the target layer, the fracturing string is lowered further to make the guide movable joint 5 go downward and insert into the sealing bushing 6, the lifting and releasing double-sealing balancing valve is in the closed position, and then the fracturing string is lowered further to pressurize the bottom seal packer 22, and then the fracturing pumping construction is carried out; S3: After the fracturing pumping construction of the target layer is completed, the fracturing string is lifted to make the guide movable joint 5 move upward and separate from the sealing bushing 6, the lifting and releasing double-sealed balancing valve is in the open position, and reverse circulation well washing is performed, and then the fracturing string is continued to be lifted to release the bottom seal packer 22, and the fracturing string is dragged to the next target layer to complete the layer change; S4: Repeat steps S2 to S3 until the multi-layer fracturing is completed.

[0023] Specifically, in step S2, when the fracturing string reaches the target layer, the target layer is located between the top seal packer 19 and the bottom seal packer 22. When the fracturing pumping construction is implemented, the throttling pressure difference generated by the sandblaster 20 is used to seal the top seal packer 19, and the fracturing fluid enters the target layer through the sandblaster 20. After the target layer is fracturing, the pump is stopped and the top seal packer 19 is unsealed. In this method, by lifting and lowering the fracturing string, the lifting and releasing double-sealed balancing valve can be switched between the open position and the closed position. When the lifting and releasing double-sealed balancing valve is in the closed position, the bottom seal packer 22 is opened. The bottom seal packer 22 is not connected to the upper fracturing string up and down, so the well-killing fluid pumped during fracturing pumping can be sprayed out from the sandblaster 20 into the target layer, which meets the construction requirements of fracturing pumping. When the lifting and releasing double-sealed balancing valve is in the open position, the bottom seal packer 22 is connected to the upper fracturing string up and down, balancing the upper and lower pressures of the bottom seal packer 22. Therefore, when the fracturing string is lifted to unseal the bottom seal packer 22, the rubber cylinder of the bottom seal packer 22 will not be damaged due to the upper and lower pressure difference of the bottom seal packer 22, thereby extending the service life of the bottom seal packer 22.

[0024] The above technical features constitute the best embodiment of the present invention, which has strong adaptability and best implementation effect. Non-essential technical features can be added or reduced according to actual needs to meet the requirements of different situations.

Claims

1. A lifting and releasing double-sealed balancing valve, characterized in that The invention comprises an upper joint, a guide seat and a cap, a guide seat, a lower joint, a guide movable joint, a sealing bushing, a steel ball baffle and a steel ball. A ball seat cone with a larger upper portion and a smaller lower portion is provided on the inner side of the upper joint, a steel ball is provided in the inner hole of the ball seat cone, a steel ball baffle is provided on the inner side of the upper joint corresponding to the upper side of the steel ball, the guide movable joint is a cylindrical structure with an open upper end and a closed lower end, the lower outer side of the upper joint is fixedly connected to the upper inner side of the guide movable joint, the outer side of the upper joint corresponding to the upper side of the guide movable joint is sleeved with a guide seat and a cap which cooperate with the upper joint for sliding sealing, the lower outer side of the guide seat and the cap is fixedly connected with the guide seat, the lower outer side of the guide movable joint is provided with an outer ring groove, the outer side of the guide movable joint corresponding to the position of the outer ring groove is sleeved with a sealing bushing and a lower joint in sequence from the inside to the outside, the sealing bushing and the guide The movable joint is sealed, the top wall of the outer ring groove and the upper end of the sealing bushing are abutted, the outer side of the sealing bushing and the inner side of the lower joint are fixedly connected, the upper outer side of the lower joint and the lower inner side of the guide seat are fixedly connected, and an annular cavity is enclosed between the upper joint, the guide movable joint, the guide seat and the cap, the guide seat, the lower joint and the sealing bushing. A first liquid passage communicating with the annular cavity is provided on the outer wall of the guide seat, and a second liquid passage communicating with the internal channel of the guide movable joint and the annular cavity is provided on the outer wall of the guide movable joint corresponding to the lower side position of the upper joint. The upper end of the guide movable joint can abut against the lower end of the guide seat and the cap when the guide movable joint moves upward relative to the sealing bushing, and the guide movable joint is separated from the sealing bushing when the upper end of the guide movable joint abuts against the lower end of the guide seat and the cap.

2. The lifting and releasing double-sealed balancing valve according to claim 1 is characterized in that A plurality of first mounting ring grooves are arranged at intervals up and down on the inner wall of the outer ring groove corresponding to the position of the sealing bushing, and a star-shaped sealing ring is installed in each first mounting ring groove.

3. The lifting and releasing double-sealed balancing valve according to claim 1 or 2, characterized in that A second mounting ring groove is arranged on the upper end surface of the sealing bushing at a position corresponding to the top wall of the outer ring groove, and an O-type sealing ring is installed in the second mounting ring groove.

4. The lifting and releasing double-sealed balancing valve according to claim 1 or 2, characterized in that The lower outer side of the upper joint and the upper inner side of the guide movable joint are connected together by threads, and a back-off screw is provided between the lower outer side of the upper joint and the upper inner side of the guide movable joint; the lower outer side of the guide seat cap and the upper inner side of the guide seat are connected together by threads, and a back-off screw is provided between the lower outer side of the guide seat cap and the upper inner side of the guide seat.

5. The lifting and releasing double-sealed balancing valve according to claim 3 is characterized in that The lower outer side of the upper joint and the upper inner side of the guide movable joint are connected together by threads, and a back-off screw is provided between the lower outer side of the upper joint and the upper inner side of the guide movable joint; the lower outer side of the guide seat cap and the upper inner side of the guide seat are connected together by threads, and a back-off screw is provided between the lower outer side of the guide seat cap and the upper inner side of the guide seat.

6. The lifting and releasing double-sealed balancing valve according to claim 1, 2 or 5, characterized in that The upper outer side of the lower joint and the lower inner side of the guide seat are connected together by threaded fixation, and a stop screw and an O-ring are provided between the upper outer side of the lower joint and the lower inner side of the guide seat; the outer side of the sealing bushing and the inner side of the lower joint are connected together by threaded fixation, and an O-ring is provided between the outer side of the sealing bushing and the inner side of the lower joint.

7. The lifting and releasing double-sealed balancing valve according to claim 3 is characterized in that The upper outer side of the lower joint and the lower inner side of the guide seat are connected together by threaded fixation, and a stop screw and an O-ring are provided between the upper outer side of the lower joint and the lower inner side of the guide seat; the outer side of the sealing bushing and the inner side of the lower joint are connected together by threaded fixation, and an O-ring is provided between the outer side of the sealing bushing and the inner side of the lower joint.

8. The lifting and releasing double-sealed balancing valve according to claim 4 is characterized in that The upper outer side of the lower joint and the lower inner side of the guide seat are connected together by threaded fixation, and a stop screw and an O-ring are provided between the upper outer side of the lower joint and the lower inner side of the guide seat; the outer side of the sealing bushing and the inner side of the lower joint are connected together by threaded fixation, and an O-ring is provided between the outer side of the sealing bushing and the inner side of the lower joint.

9. A method for unsealing a fracturing packer by auxiliary dragging of a tubing string using a lifting and releasing double-sealed balancing valve as claimed in any one of claims 1 to 8, characterized in that The following steps are involved: S1: Lowering the fracturing string into the well. The fracturing string includes a safety joint, a hydraulic anchor, a top seal packer, a sandblaster, a lifting double seal balancing valve, a bottom seal packer and a guide head which are connected to the oil pipe in sequence from top to bottom. During the lowering process, the guide movable joint is separated from the sealing bushing, and the lifting double seal balancing valve is in the open position; S2: When the fracturing string reaches the target layer, continue to lower the fracturing string to make the guide movable joint go down and insert into the sealing bushing, the lifting and releasing double-sealing balancing valve is in the closed position, and then continue to lower the fracturing string to pressurize the bottom seal packer, and then implement the fracturing pumping construction; S3: After the fracturing pumping construction of the target layer is completed, the fracturing string is lifted up to separate the guide movable joint from the sealing bushing, the lifting and releasing double-sealed balancing valve is in the open position, and reverse circulation well washing is performed. Then the fracturing string is further lifted up to release the bottom seal packer, and the fracturing string is dragged to the next target layer to complete the layer change; S4: Repeat steps S2 to S3 until the multi-layer fracturing is completed.

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