Oil pipe temporary plugging device and oil pipe temporary plugging short starting method

Abstract

The invention relates to the technical field of open flow after oil field fracturing, in particular to an oil pipe temporary plugging device and an oil pipe temporary plugging short starting method. According to the oil pipe temporary plugging device and the oil pipe temporary plugging short starting method, the outer cylinder is put into a well along with a pipe column, a plugging device is put in, the pipe column is fixed and plugged through a machine body structure and a positioning mechanism, the pipe column is lifted to enable a large-diameter tool to be located above a fractured stratum, then pressure is applied to the interior of the well to enable a shear pin to be fractured, and the pressure pushes a valve element to move downwards; and after the pipe column recovers circulation, the blowout work is continued. According to the oil pipe temporary plugging device and the oil pipe temporary plugging short starting method, the outer cylinder is put into the well along with the fracturing pipe column, then the plugging device is put, the fracturing pipe column is plugged, large-diameter tools such as a packer in the pipe column are lifted to the position above the fracturing well section, then open flow is recovered, sand can be settled to the artificial well bottom after formation sand production, the pipe column cannot be influenced, and the oil pipe temporary plugging short starting method has the advantages of being simple in structure and convenient to operate. And the phenomenon that large-diameter tools such as a packer are buried and blocked by gravels, so that a pipe column is buried by sand and blocked by the gravels is avoided.

Description

Technical Field

[0001] This invention relates to the field of post-fracture venting technology in oilfields, and particularly to a tubing temporary plugging device and a method for short-circuiting the tubing temporary plugging. Background Technology

[0002] In oilfield fracturing, post-fracturing venting is typically performed after downhole fracturing. However, after multi-stage downhole fracturing, many large-diameter tools, such as packers, are located below the perforated section. The wellbore wall in the fracturing section is fragile, making it prone to dropping sand and gravel particles downhole, leading to sand production. After sand production, large-diameter tools below are susceptible to sand jamming and tubing burial, preventing the tubing from being pulled up smoothly, affecting subsequent operations and increasing construction difficulty. Current technology typically controls formation sand production by selecting venting nozzles. However, if the sand production is insufficient to return to the surface with the flowback fluid, it's impossible to directly assess the appropriateness of the nozzle selection. Sand settling in the wellbore can still cause sand jamming. Therefore, to address these shortcomings, a tubing temporary plugging device and a short-start method for the temporary plugging are proposed. Summary of the Invention

[0003] (a) Technical problems to be solved To address the shortcomings of existing technologies, this invention provides a temporary plugging device for oil pipes and a method for temporarily plugging and short-starting oil pipes, which solves the problem in existing technologies where improper selection of the release nozzle makes it impossible to intuitively determine whether the nozzle is suitable, resulting in sand settling and still causing sand jamming accidents.

[0004] (II) Technical Solution To solve the above problems, the present invention provides an oil pipe temporary plugging device, comprising: The system comprises an outer cylinder and a plug. The outer cylinder is mounted on the fracturing tubing string and lowered into the well along with the fracturing tubing string. The plug is cylindrical and its shape matches the inner wall of the outer cylinder, with the contact surface between the two having a stepped structure. A positioning mechanism is provided between the plug and the outer cylinder, which cooperates with the stepped structure to fix the plug. A valve core is provided inside the plug, which is inserted into the plug from bottom to top. The valve core is connected to the plug via a shear pin. When the valve core is fixed inside the plug, the plug seals the outer cylinder. Pushing the valve core downwards connects the upper and lower parts of the plug, releasing the seal inside the outer cylinder.

[0005] Preferably, the inner wall of the outer cylinder is provided with a circumferential positioning groove, and the outer wall of the plugger is provided with a plurality of anchor claw grooves evenly distributed along the circumferential direction. The position of the anchor claw groove corresponds to the positioning groove. Each anchor claw groove contains an anchor claw, and an elastic body is provided behind each anchor claw for support. The positioning mechanism includes a positioning groove, an anchor claw groove, and an anchor claw.

[0006] Preferably, the plug has an annular spring seat above the valve core, the position of the spring seat corresponds to the position of the anchor claw groove, and the anchor claw groove penetrates the side wall of the plug; the elastic body is installed between the anchor claw and the spring seat.

[0007] Preferably, the top of the plug is provided with a plugging ring, and the plugging ring is bolted to the plug, the plugging ring sealing the gap between the top of the plug and the top of the spring seat.

[0008] Preferably, the spring seat is provided with a plurality of radially penetrating connecting holes, the positions of which correspond to the positions of the anchor claw grooves.

[0009] Preferably, the elastic support is a spring sheet.

[0010] Preferably, the plug and the spring seat are connected by a fixing screw.

[0011] In addition, the present invention also provides a method for temporarily plugging and shorting a tubing, using the tubing temporary plugging device described above, comprising: Step 1: Install the outer casing onto the fracturing tubing string and lower it into the well along with the fracturing tubing string; Step 2: During the post-pressure release, lower the plug along the tubing to the outer cylinder to seal the tubing; Step 3: After confirming that the oil pipe is successfully blocked, stop the pump, open the wellhead vent valve to release pressure, and confirm whether the blockage is successful. Step 4: Remove the wellhead and install the blowout preventer, self-sealing rubber core, plug valve, tubing short connector, and pull up the tubing so that the downhole packer and other tools are located in the upper part of the fracturing section; Step 5: Connect the pump truck to pressurize the oil pipe and push the valve core downward to restore flow in the tubing; Step 6: Disconnect the pump truck pipeline and connect the discharge pipeline to continue discharge.

[0012] (III) Beneficial Effects The tubing temporary plugging device and tubing temporary plugging short-lift method provided by the present invention involve placing a plugging device after the outer cylinder is lowered into the well along with the fracturing tubing string to plug the fracturing tubing string. Afterwards, the tubing string is lifted up, which can lift large-diameter tools such as packers inside the tubing string to the fracturing section. Even if sand is produced in the formation, it will sink to the artificial bottom of the well and will not affect the tubing string. This prevents large-diameter tools such as packers from being buried or stuck by sand and gravel, thus reducing the failure rate of the oil well. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the oil pipe temporary plugging device of the present invention.

[0014] The components are: 1. Outer cylinder; 2. Blocker; 3. Spring seat; 4. Plug ring; 5. Valve core; 6. Shear pin; 7. Anchor claw; 8. Spring plate; 9. Fixing screw. Detailed Implementation

[0015] 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 some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0016] In the description of this invention, it is necessary to understand that the orientation or positional relationship indicated by terms such as "upper", "lower", "inner", "outer", "top", and "bottom" are based on the orientation or positional relationship shown in the accompanying drawings. The purpose is only to facilitate the description of this invention and to simplify the description. It is not intended to indicate or imply that the component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention. Example

[0017] like Figure 1 As shown, this invention provides a tubing temporary plugging device, specifically comprising: an outer cylinder 1 and a plugger 2. The outer cylinder 1 is mounted on a fracturing tubing string and lowered into the well along with the fracturing tubing string. The outer cylinder 1 serves as the main body of the device, and its operating position can be changed by adjusting its installation position on the fracturing tubing string. Generally, the contact surface between the outer cylinder 1 and the plugger 2 has a stepped structure to prevent the plugger 2 from moving downwards along the outer cylinder 1 and detaching from it, thus preventing device failure. The shape of the plugger 2 matches the shape of the inner wall of the outer cylinder 1.

[0018] The plug 2 is provided with a positioning mechanism between it and the outer cylinder 1. This mechanism is used to fix the plug 2 inside the outer cylinder 1, preventing the plug 2 from moving upward under pressure and separating from the outer cylinder 1, thus causing the device to fail to seal. Normally, during operation, the outer cylinder 1 is first lowered into the well along with the fracturing tubing. When the plug 2 needs to be used, it is then lowered into the well. When the plug 2 passes the outer cylinder 1, the positioning mechanism works in conjunction with the outer cylinder 1 to limit the plug 2, preventing it from moving upward.

[0019] It should be noted that the inner wall of the outer cylinder 1 is provided with a circumferential positioning groove, and the outer wall of the plug 2 is provided with several anchor claw grooves evenly distributed circumferentially. The position of the anchor claw grooves corresponds to the positioning grooves, and each anchor claw groove contains an anchor claw 7. The positioning mechanism includes a positioning groove, an anchor claw groove, and an anchor claw 7. Each anchor claw 7 is supported by an elastic body. When the plug 2 is lowered into the well and comes into contact with the outer cylinder 1, the elastic body pushes the anchor claw 7 outward and engages it in the positioning groove, thereby fixing the plug 2 to the outer cylinder 1.

[0020] In this invention, the plug 2 is cylindrical, and a valve core 5 is provided inside the plug 2. The valve core 5 is inserted into the plug 2 from bottom to top, and the valve core 5 is connected to the plug 2 by a shear pin 6. When the valve core 5 is fixed inside the plug 2, the plug 2 seals the outer cylinder 1. After the valve core 5 is pushed downward, the plug 2 is connected vertically, and the seal inside the outer cylinder 1 is released. In actual operation, after the plug 2 is fixed inside the outer cylinder 1, the valve core 5 is not separated from the plug 2. The plug 2 and the valve core 5 work together to seal the outer cylinder 1, thereby sealing the entire fracturing string. At this time, the liquid in the string above the outer cylinder 1 can be discharged, and the string can be lifted to raise the packer and other large-diameter equipment above the pressure formation. After the string is lifted, pressure is reapplied to the string. The pressure in the string acts on the valve core 5 and is supported by the shear pin 6. When the shear stress on the shear pin 6 exceeds its stress limit, the shear pin 6 breaks. At this time, the valve core 5 will separate from the plug 2 under the pressure in the string, opening the plug 2 and restoring the passage of the outer cylinder 1 and the entire string. After that, the venting operation can continue. The plug 2 and the spring seat 3 are connected by fixing screws 9. To ensure good sealing during operation, several sealing rings are provided between the valve core 5 and the plug 2.

[0021] Generally, when selecting shear pin 6, it should be ensured that the pressure of shear pin 6 during operation will not damage other downhole equipment such as tubing and fracturing string, to prevent excessive pressure in the fracturing string during pressure shearing of shear pin 6, which could damage other devices on the string.

[0022] The valve core 5 is provided with an annular spring seat 3 above it. The position of the spring seat 3 corresponds to the position of the anchor claw groove, which penetrates the side wall of the blocker. An elastic body is installed between the anchor claw 7 and the spring seat 3. Generally, the elastic body is a spring sheet 8. In practical applications, the elastic body can be replaced with a spring or other objects with good elasticity according to the on-site working requirements.

[0023] It is important to note that the top of the plug 2 is equipped with a plugging ring 4, which is bolted to the plug 2. The plugging ring 4 seals the gap between the top of the plug 2 and the top of the spring seat 3, preventing the fluid in the fracturing string from flowing downwards and causing the elastomer to fail during operation, thus extending the service life of the device. The spring seat 3 is provided with several radially penetrating connecting holes, the positions of which correspond to the positions of the anchor claw grooves. During operation, the fluid in the fracturing string will always flow into the space between the spring seat 3 and the plug 2 through the connecting holes to balance the pressure inside and outside the spring seat 3, preventing damage to the spring seat 3 due to excessive pressure difference under high-pressure operating conditions.

[0024] Example 2: As shown above, the present invention also provides a method for partially suspending a temporary plug using the above-mentioned oil pipe temporary plugging device, which includes: Step 1: Install the outer casing onto the fracturing tubing string and lower it into the well along with the fracturing tubing string; Step 2: During the post-pressurization blowout preventer, lower the plug along the tubing string to the outer cylinder to seal the tubing string; Step 3: After confirming that the oil pipe has been successfully blocked, stop the pump, open the blowout preventer valve of the wellhead to release pressure, and confirm whether the blockage has been successful. Step 4: Remove the wellhead and install the blowout preventer, self-sealing rubber core, plug valve, tubing short connector, and pull up the tubing so that the downhole packer and other tools are located in the upper part of the fracturing section; Step 5: Connect the pump truck to pressurize the oil pipe and push the valve core downward to restore flow in the tubing; Step 6: Disconnect the pump truck pipeline and connect the discharge pipeline to continue discharge.

[0025] In step two, after the plug 2 falls into the outer cylinder 1, the anchor claw 7 pops out under the action of the elastic body and cooperates with the stepped structure to fix the position of the plug 2. At this time, the valve core 5 is installed in the plug 2, and the plug seals the outer cylinder 1, causing the pressure in the fracturing sleeve to gradually increase.

[0026] In step three, the success of tubing plugging can be determined by observing the downhole pressure. Generally, after the plug is deployed, the pressure inside the fracturing string will suddenly rise. At this point, the pump at the wellhead is shut off and the blowout preventer (BOP) valve on the Christmas tree is opened to release pressure. When no fluid is discharged from the blowout port, the BOP valve is closed and the operation is observed for a period of time. If the pressure remains at 0, the plugging is considered successful. The observation period is typically 15 minutes.

[0027] The tubing temporary plugging device and tubing temporary plugging short-lift method provided by this invention can lift large-diameter tools such as packers from downhole to the fracturing section, so that the large-diameter tools are not affected by downhole sand production and prevent sand jamming accidents. The specific working process of this invention is as follows: Step 1: Install the outer casing onto the fracturing tubing string and lower it into the well along with the fracturing tubing string.

[0028] Step 2: During the post-pressure blowout preventer operation, the plug is lowered along the tubing string to the outer cylinder to seal the tubing string. During this process, the plug moves downwards and sits on the stepped structure inside the outer cylinder. The anchor claws, after entering the fixing groove, pop outwards to engage with the groove and prevent the plug from moving upwards. At this point, the plug seals the outer cylinder, and the tubing string is blocked.

[0029] Step 3: After confirming successful tubing plugging, stop the pump and open the Christmas tree blowout preventer to release pressure and confirm successful plugging. At this point, after the plug is in contact with and fixed to the outer casing, observe the downhole pressure. When the pressure suddenly rises, it indicates that the plug is fixed inside the outer casing. Shut down the working pump on the well and open the Christmas tree blowout preventer to release pressure in the well. After no liquid flows out of the blowout, continue to observe the well pressure. If the well pressure remains at 0 after 15 minutes, the tubing plugging is confirmed to be successful.

[0030] Step 4: Remove the wellhead and install the blowout preventer, self-sealing rubber core, plug valve, and tubing short-circuit. Pull up the tubing so that the downhole packer and other tools are located in the upper part of the fracturing section.

[0031] Step 5: Connect the pump truck to pressurize the tubing and push the valve core downwards to restore flow within the tubing string. During this process, as the pump truck pressurizes, the downhole pressure gradually increases. When the force acting on the shear pin exceeds the shear pin's stress limit, the shear pin breaks, the valve core loses its fixation and falls downwards into the well, and flow is restored to the tubing string.

[0032] Step Six: Disconnect the pump truck pipeline and connect the venting pipeline to continue venting. After the venting operation continues, even if sand is produced in the formation during the operation, it will gradually settle to the bottom of the artificial well and will not come into contact with large-diameter tools such as packers, thus not affecting the tubing string.

[0033] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A temporary plugging device for oil pipes, characterized in that, include: The outer cylinder (1) and the plug (2) are installed on the fracturing tubing and are lowered into the well along with the fracturing tubing. The plug (2) is cylindrical and matches the shape of the inner wall of the outer cylinder (1), and the contact surface between the two is a stepped structure. A positioning mechanism is provided between the plug (2) and the outer cylinder (1) to fix the plug (2) in cooperation with the stepped structure. A valve core (5) is provided inside the plug (2). The valve core (5) is inserted into the plug (2) from bottom to top. The valve core (5) is connected to the plug (2) through a shear pin (6). When the valve core (5) is fixed inside the plug (2), the plug (2) seals the outer cylinder (1). After the valve core (5) is pushed down, the plug (2) is connected from top to bottom, and the seal inside the outer cylinder (1) is released.

2. The tubing temporary plugging device according to claim 1, characterized in that, The inner wall of the outer cylinder (1) is provided with a circumferential positioning groove, and the outer wall of the plug (2) is provided with a number of anchor claw grooves evenly arranged in the circumferential direction. The position of the anchor claw groove corresponds to the positioning groove. Each anchor claw groove is provided with an anchor claw (7), and each anchor claw (7) is supported by an elastic body. The positioning mechanism includes a positioning groove, an anchor claw groove and an anchor claw (7).

3. The tubing temporary plugging device according to claim 2, characterized in that, The plug (2) has an annular spring seat (3) above the valve core (5). The position of the spring seat (3) corresponds to the position of the anchor claw groove, and the anchor claw groove penetrates the side wall of the plug. The elastic body is installed between the anchor claw (7) and the spring seat (3).

4. The tubing temporary plugging device according to claim 3, characterized in that, The top of the plug (2) is provided with a plug ring (4), and the plug ring (4) is bolted to the plug (2). The plug ring (4) seals the gap between the top of the plug (2) and the top of the spring seat (3).

5. The tubing temporary plugging device according to claim 4, characterized in that, The spring seat (3) is provided with several radially penetrating connecting holes, the positions of which correspond to the positions of the anchor claw grooves.

6. The tubing temporary plugging device according to claim 4, characterized in that, The elastic support is a spring sheet (8).

7. The tubing temporary plugging device according to claim 4, characterized in that, The plug (2) and the spring seat (3) are connected by a fixing screw (9).

8. A method for temporarily plugging and shorting a tubing, using the tubing temporary plugging device according to any one of claims 1-7, comprising: Step 1: Install the outer casing onto the fracturing tubing string and lower it into the well along with the fracturing tubing string; Step 2: During the post-pressure release, lower the plug along the tubing to the outer cylinder to seal the tubing; Step 3: After confirming that the oil pipe is successfully blocked, stop the pump, open the wellhead vent valve to release pressure, and confirm whether the blockage is successful. Step 4: Remove the wellhead and install the blowout preventer, self-sealing rubber core, plug valve, tubing short connector, and pull up the tubing so that the downhole packer and other tools are located in the upper part of the fracturing section; Step 5: Connect the pump truck to pressurize the oil pipe and push the valve core downward to restore flow in the tubing; Step 6: Disconnect the pump truck pipeline and connect the discharge pipeline to continue discharge.

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