Pipe jacking and blowout prevention deblocking process for long-stop shallow-shut well

Abstract

The invention relates to the technical field of petroleum engineering, and discloses a long-stop shallow-shut well pipe-jacking-preventing and blowout-preventing deblocking process which comprises the following steps: step 1, washing a well to ensure that a pipe column is unblocked, and meanwhile, installing a blowout preventer, a balance blowout preventer and a split type upward jacking-preventing device; secondly, by means of the combined blowout prevention device, the blowout prevention function in two stages of oil pipes in the well and the well mouth is achieved, and a pressure relief space and a circulation channel are reserved; 3, confirming that the bridge plug is fished when the load rises; step 4, slowly lifting and lowering the movable pipe column until the rubber sleeve is unsealed; and 5, if continuous overflow occurs in the casing pipe, it is judged that fishing succeeds, in the first step, pressure testing is conducted on a blowout preventer, a blowout prevention pipeline and a blowout opening pipeline, and it is guaranteed that no thorn or leakage exists at the connecting position. According to the process, a combined blowout prevention device is adopted, meanwhile, a pressure relief space and a circulation channel are reserved, it is guaranteed that a connecting part is free of stabs and leakage, the sealing performance and reliability of a system are improved, and the leakage risk is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of petroleum engineering, in particular to a long-stop shallow well sealing and unsealing process for preventing pipe jacking and blowout. Background Art

[0002] In oil and gas drilling operations, due to the existence of formation pressure and wellbore pressure, the unsealing of wellheads in long-term shutdown and shallow sealing states often faces the challenges of preventing pipe jacking and blowout. Traditional unsealing methods often have safety risks, which are prone to cause blowout accidents and pose serious threats to workers and equipment. In order to solve the safety problems in the unsealing process of long-term shallow wellheads, some unsealing processes for preventing blowout and jacking have been proposed. Some test wells and temporary wells have been shut down for more than 10 years. When the bridge plug is unsealed, there are risks such as pressure release, blowout, and pipe column jacking. There may be pipe flying accidents. There are three main reasons: First, due to the long well sealing time, the well pressure is held back to form a closed pressure. After the bridge plug is unsealed and the well pressure increases and gas is channeled, the weight of the pipe column and the liquid column is less than the jacking force of the jacking pressure on the pipe column, causing the pipe column to jack up. Second, the downhole static liquid column pressure is low and the tubing is light, which can easily cause the tubing to fly. Third, the tubing is connected to large-diameter tools, and the rubber tubes of the bridge plug unsealing well and the fracturing well have not been completely retracted, but are tightly attached to the inner wall of the casing, and are close to or have filled the annular space.

[0003] There are two traditional methods for preventing wellhead top-up and blowout: one is the traditional wellhead top-up method, which is a manual anti-top-up slip that requires manual operation at the wellhead, relying on the self-locking force of the slip to prevent the pipe from top-up, and the control time depends on the worker's reaction and operation speed; when the bridge plug is unsealed, the pressure is released instantly, the top-up speed is fast, and the impact force is strong, which makes it difficult to fully guarantee the safety of the operator and timely control of the top-up of the pipe. The second is to throw a plugger into the pipe, which makes it difficult to retain the well killing channel during the unsealing process.

[0004] The conventional practice for unsealing long-stopped wells is to use pressurized operations to unseal them, but the construction cost of a single well is high. At the same time, pressurized operations occupy the well for a long time and are inefficient. During the peak construction period, the team is tight and it is difficult to carry out operations on multiple wells, which seriously affects the construction progress. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention provides a long-stop shallow sealed well unsealing process for preventing pipe jacking and blowout, which solves the problem that the conventional practice of unsealing long-stop wells is to use pressurized operations to unblock, but the construction fee of a single well is high, the construction cost is high, and the pressurized operation occupies a long time in the well and has low efficiency.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solutions: a long-stop shallow well sealing anti-pipe jacking and anti-blowout unsealing process, comprising the following steps: Step 1: Wash the well to ensure that the pipe string is unobstructed, and install the blowout preventer, balanced blowout preventer and split-valve anti-lifting device at the same time; Step 2: Using the combined blowout prevention device, the blowout prevention function is realized in the two-stage oil pipes of the downhole and wellhead, and the pressure relief space and circulation channel are reserved; Step 3: Load increase confirms that the bridge plug has been retrieved; Step 4: Slowly lift and lower the movable pipe column until the rubber cartridge is unsealed; Step 5: Continuous overflow occurs in the casing, indicating that the salvage is successful.

[0007] Preferably, in step one, the blowout preventer, blowout preventer pipeline, and blowout release pipeline are pressure tested to ensure that the connection parts are free of punctures and leaks.

[0008] Preferably, in step one, the petal-type anti-lifting device is composed of a circular steel body with an inner diameter of 74.5 mm and a 5 mm thick resin, has a buffering function, can extend the impact time to 0.6 s, and has a maximum impact force of 282 kN.

[0009] Preferably, in the step 1, the annular steel body and the resin are connected via a connecting piece.

[0010] Preferably, in step 2, a combined blowout prevention device is used which is a combination of a reverse check valve and a plug valve to achieve blowout prevention in two-stage oil pipes, downhole and wellhead, and retain pressure relief space and a circulation channel.

[0011] Preferably, in step 2, the operation is stopped for observation for 4 hours after the blowout, and the following observations are made: the casing pressure drop is 0 MPa, and there is no upward trend, and no toxic or harmful gas is detected at the wellhead.

[0012] Preferably, in step 2, if there is no overflow at the wellhead and the tubing is not lifted up, the tubing in the well is pulled out normally, and if the pressure relief is ineffective, the tubing in the well is pulled out under pressure through the cooperation of the balanced pressure, the balanced blowout preventer and the hydraulic blowout preventer.

[0013] Preferably, in step 4, the tubing string is slowly lifted up, and the increase in load confirms that the bridge plug has been fished out, and the movable tubing string is slowly lifted up and lowered until the rubber cartridge is unsealed and continuous overflow occurs in the casing, and it is determined that the salvage is successful.

[0014] Preferably, in step 4, the condition of the tubing in the well is controlled.

[0015] Preferably, in step five, during the unsealing process, the working states of the blowout preventer and the anti-lifting device are adjusted by real-time monitoring of the wellhead pressure and the tubing pressure to ensure the safety of the unsealing process, and during the shutdown observation period after the blowout, the gas in the wellbore is extracted and analyzed to ensure that no toxic or harmful gases are present.

[0016] The present invention provides a long-stop shallow well sealing and unsealing process to prevent pipe jacking and blowout. It has the following beneficial effects: The present invention adopts a combined blowout preventer through the process. Through the coordinated use of a blowout preventer, a balanced blowout preventer and a split-flap anti-lifting device, the occurrence of wellhead pipe jacking and blowout can be effectively prevented. At the same time, a pressure relief space and a circulation channel are reserved to ensure the safety and effectiveness of the working process. The blowout preventer, the blowout preventer pipeline and the blowout release pipeline are pressure tested to ensure that the connection parts are free of punctures and leaks, thereby improving the sealing and reliability of the system and reducing the risk of leakage.

[0017] The present invention adopts a circular steel body and resin structure through a split-flap anti-lifting device, has a buffering function, can extend the impact time to 0.6 seconds, and has a maximum impact force of 282kN, effectively protecting the integrity of the equipment and the wellhead, and can control the status of the pipe string in the well by adjusting the parameters of the balance pressure, the balance blowout preventer and the hydraulic blowout preventer. When pulling out the pipe string in the well under pressure, it can be adjusted according to the actual situation to ensure the flexibility and safety of the operation.

[0018] The present invention can timely adjust the working parameters of the blowout preventer and the anti-lifting device by real-time monitoring of the wellhead pressure and the oil pipe pressure during the unblocking process to ensure the safety of the unblocking process. At the same time, during the shutdown observation period after the blowout, the gas in the wellbore can also be extracted and analyzed to ensure that there is no toxic or harmful gas.

[0019] The present invention uses this process to clarify the unsealing top force at different well sealing depths, give a safe unsealing limit, innovatively design a long-stop well safe unsealing process, cooperate with the annulus pressure replenishment method to balance the formation pressure, effectively control the top of the pipe string and overflow in the oil pipe, achieve safe unsealing, improve the unsealing process, and save costs while ensuring well control safety and environmentally friendly operations. DETAILED DESCRIPTION

[0020] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Embodiment 1

[0021] The embodiment of the present invention provides a long-stop shallow well sealing anti-pipe jacking and anti-blowout unsealing process, comprising the following steps: Step 1: Wash the well to ensure that the pipe string is unobstructed, and install the blowout preventer, balanced blowout preventer and split-valve anti-lifting device at the same time; Step 2: Using the combined blowout prevention device, the blowout prevention function is realized in the two-stage oil pipes of the downhole and wellhead, and the pressure relief space and circulation channel are reserved; Step 3: Load increase confirms that the bridge plug has been retrieved; Step 4: Slowly lift and lower the movable pipe column until the rubber cartridge is unsealed; Step 5: Continuous overflow occurs in the casing, indicating that the salvage is successful.

[0022] In step 1, the pipe string is kept clear by washing the well, and a blowout preventer, a balanced blowout preventer and a split-flap anti-lift device are installed. The blowout preventer can prevent the occurrence of a blowout, the balanced blowout preventer is used to balance the pressure at the wellhead and downhole, and the split-flap anti-lift device has a buffering function to protect the integrity of the equipment and the wellhead; In step 2, by using a combined blowout prevention device, the blowout prevention function is achieved in the two-stage oil pipes at the downhole and wellhead, and the pressure relief space and circulation channel are retained. This can effectively control the pressure at the wellhead and downhole to avoid the occurrence of blowouts; In step 3, the load rises to confirm that the bridge plug has been retrieved. By increasing the load, it is verified whether the obstruction (bridge plug) at the wellhead has been successfully retrieved to ensure that the unblocking work can continue; In step 4, slowly lift and lower the active pipe column until the rubber cartridge is unsealed. By controlling the speed and strength of lifting, the rubber cartridge is successfully unsealed, creating conditions for subsequent operations; In step 5, if the casing overflows continuously, the salvage is considered successful. Continuous overflow indicates that the pressure in the well has been effectively released, and the risk of wellhead jacking and blowout is greatly reduced.

[0023] In step 1, the blowout preventer, blowout preventer pipeline, and blowout release pipeline are pressure tested to ensure that there are no punctures or leaks at the connection parts; Pressure test the blowout preventer, blowout preventer line, and blowout line: After installing the blowout preventer, blowout preventer line, and blowout line, a pressure test is required to ensure that the connection parts are free of punctures and leaks. During the pressure test, appropriate liquid or gas medium can be used to apply a certain pressure to check whether there is water or air leakage at the connection parts.

[0024] In step 1, the split-flap anti-lifting device is composed of a circular steel body with an inner diameter of 74.5 mm and a 5 mm thick resin. It has a buffering function and can extend the impact time to 0.6 s. The maximum impact force is 282 kN. The structure of the split-flap anti-lift device: The device is composed of a circular steel body with an inner diameter of 74.5mm and a 5mm thick resin. The circular steel body has a certain rigidity and strength, which can provide support and protection; while the resin has good buffering performance, which can absorb the impact energy and prolong the impact time; Buffering function: The split-flap anti-lifting device can effectively reduce the impact force when the movable pipe column is lifted up and lowered through the buffering performance of the resin material. When the movable pipe column collides with the device, the resin can absorb and disperse the impact energy, extending the impact time to 0.6 seconds, thereby reducing the peak impact force; Maximum impact force: The maximum impact force of the split-type anti-lifting device is 282kN. This means that when the active pipe string collides with the device, the peak impact force will not exceed 282kN, thus protecting the integrity of the device and the wellhead.

[0025] In step 1, the split-flap anti-lifting device is composed of a circular steel body with an inner diameter of 74.5 mm and a 5 mm thick resin, and the circular steel body and the resin are connected by a connector; The petal-type anti-lifting device consists of a circular steel body with an inner diameter of 74.5mm and a 5mm thick resin. The circular steel body is usually made of high-strength alloy steel and has sufficient rigidity and strength to support the lowering and lifting of the movable pipe column. The resin is a material with good buffering properties and is used to absorb and disperse impact energy.

[0026] In step 2, a combined blowout prevention device is used, which is a combination of a reverse check valve and a plug valve, to achieve blowout prevention in the downhole and wellhead two-stage oil pipes, and retain the pressure relief space and circulation channel; In the combined blowout preventer, it is necessary to reserve pressure relief space and circulation channel. Pressure relief space refers to the space used to accommodate the sprayed oil and gas to reduce the danger and loss caused by the spray. The circulation channel refers to the channel used to guide the sprayed oil and gas back to the ground or other processing equipment for subsequent processing and control. This can ensure that in the event of a blowout accident, the sprayed oil and gas can be handled in time to reduce the impact on the environment and personnel.

[0027] In step 2, the operation was stopped for observation for 4 hours after the blowout, and the following observations were made: the casing pressure dropped to 0 MPa, with no upward trend, and no toxic or harmful gas was detected at the wellhead; Through the above observations, it can be determined whether the system is in a stable state after the blowout, whether the oil and gas are fully controlled, and whether the wellhead is safe. If the casing pressure drops to 0MPa, there is no upward trend, and no toxic or harmful gases are detected at the wellhead, it can be considered that the wellhead environment is stable and the next operation or maintenance work can be carried out.

[0028] In step 2, if there is no overflow at the wellhead and the pipe string does not go up, the pipe string in the well is pulled out normally. If the pressure relief is ineffective, the pipe string in the well is pulled out under pressure through the cooperation of the balanced pressure, the balanced blowout preventer and the hydraulic blowout preventer; Perform normal pulling out of the tubular in the well, which includes using drilling tools or drilling tools to pull out the tubular section by section to ensure that the tubular is pulled out smoothly from the well. During this process, it is necessary to pay attention to maintaining smooth operation to avoid tubular jamming or other abnormal situations; Pulling out with pressure when pressure relief is ineffective: If pressure relief is ineffective, that is, the pressure in the well cannot be reduced to a safe range through natural pressure relief, it is necessary to use the method of pulling out with pressure. During the process of pulling out with pressure, the pressure in the well can be controlled by the coordination of the balance pressure, the balanced blowout preventer and the hydraulic blowout preventer to ensure the safety of the operation.

[0029] In step 4, slowly lift the tubing string, and the increase in load confirms that the bridge plug has been retrieved. Slowly lift and lower the active tubing string until the rubber cylinder is unsealed and the casing overflows continuously, which indicates that the salvage is successful: After confirming that the bridge plug has been retrieved, continue to slowly lift the tubing string. This is done to avoid damage to the casing or other equipment caused by lifting too quickly, while ensuring the safety of the operation; the increase in load confirms that the bridge plug has been retrieved: as the tubing string is lifted, you will observe that the load gradually increases. The increase in load is due to the presence of the bridge plug, which will bring additional resistance to the tubing string. When the load rises and stabilizes, it can be determined that the bridge plug has been successfully retrieved; slowly lift and lower the active tubing string: after confirming that the bridge plug has been retrieved, it is necessary to continue to slowly lift the tubing string until the active tubing string is lowered. The active tubing string is a special tool used to retrieve the bridge plug. When the active tubing string is lowered, it will separate from the bridge plug.

[0030] In step 4, the condition of the tubing in the well is controlled.

[0031] In step 5, during the unblocking process, the working status of the blowout preventer and the anti-lifting device is adjusted through real-time monitoring of the wellhead pressure and the tubing pressure to ensure the safety of the unblocking process. During the shutdown observation period after the blowout, the gas in the wellbore is extracted and analyzed to ensure that there is no toxic or harmful gas. Real-time monitoring of wellhead pressure and tubing pressure: During the unblocking process, it is necessary to monitor the changes in wellhead pressure and tubing pressure in real time. This can be achieved by installing corresponding pressure sensors and connecting them to the monitoring system. The monitoring system will provide real-time pressure data to help operators understand the pressure situation in the well; Adjust the working status of the blowout preventer and the anti-lifting device: The blowout preventer is used to control the wellhead pressure to prevent the sprayed liquid or gas from causing harm to personnel and equipment; the anti-lifting device is used to prevent the pipe string from lifting due to the change of pressure in the well. By adjusting the working parameters of these devices, the pressure changes during the unblocking process can be better controlled to ensure the safety of the operation.

[0032] Comparative Example 1: The Gu 12-92-Slant 106 well was constructed in October 2021 and lasted for 7 days. Thanks to the continuous efforts of technical personnel, it was safely unsealed.

[0033] The construction strictly implemented the engineering management plan, and the main processes implemented are as follows: 1. Install the controller: Install the 3FZ18-21 BOP. Use clean water (add antifreeze in winter) to test the pressure of the BOP, BOP pipeline, and blowout pipeline respectively; all the connection parts are not punctured or leaky, and the BOP and well control manifold are all qualified in the pressure test.

[0034] 2. Lowering the salvage pipe string: lowering Φ114mmFXY445-114D salvageable bridge plug special salvage tool 1 piece, Φ114 screen pipe 1 piece, Φ73mm reverse check valve 1 piece, 52 pieces of Φ73mm oil pipes, and encountering resistance at a depth of 487.68 meters.

[0035] 3. Wash the well to ensure the pipe is unobstructed.

[0036] 4. Unseal the packer: Install the anti-top slips, slowly lift the tubing string, and the increase in load confirms that the bridge plug has been fished out. Slowly lift and lower the movable tubing string until the rubber sleeve is unsealed and continuous overflow occurs in the casing, which means that the salvage is successful.

[0037] 5. Carry out blowout and stop work for 4 hours for observation. Closely observe the casing pressure which is 0.2MPa and has no upward trend. Check the wellhead and find no toxic or harmful gases.

[0038] 6. Wash the well.

[0039] 7. Lifting and salvaging pipe string: 52 pieces of Φ73mm oil pipes, 1 reverse check valve, 1 Φ114mm eccentric, 1 special salvaging tool for Φ114mmFXY445-114D salvageable bridge plug, 1 Φ114mmFXY445-114D salvageable bridge plug, 1 Φ73mm wire plug, and 1 Φ118mm wax scraper.

[0040] Leak test Leakage test Stress Testing Vibration test Leakage rate test Liquid Penetration Test Gas Permeation Test Embodiment 1 0% 100% normal 0% 5% 0% Low penetration Comparative Example 1 100% 0% Too high 100% 20% 100% High penetration Table 1 Based on the results of the above data tables, we analyzed and summarized Example 1 and the comparative results. Example 1 performed well in leakage test, sealing test, durability test and liquid penetration test, without leakage, passed the sealing test, passed the durability test and had no liquid penetration. However, in other test items, such as pressure test, temperature test and vibration test, Example 1 faced some challenges, such as excessive pressure, exceeding the temperature range and loosening. Overall, Example 1 performed better than the comparative results in multiple test items, so it was concluded that the present invention has good sealing and reliability, while also reducing the risk of leakage.

[0041] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A long-term shallow well sealing and unsealing process to prevent pipe jacking and blowout. It is characterized in that The following steps are involved: Step 1: Wash the well to ensure that the pipe string is unobstructed, and install the blowout preventer, balanced blowout preventer and split-valve anti-lifting device at the same time; Step 2: Using the combined blowout prevention device, the blowout prevention function is realized in the two-stage oil pipes of the downhole and wellhead, and the pressure relief space and circulation channel are reserved; Step 3: Load increase confirms that the bridge plug has been retrieved; Step 4: Slowly lift and lower the movable pipe column until the rubber cartridge is unsealed; Step 5: Continuous overflow occurs in the casing, indicating that the salvage is successful.

2. According to claim 1, a long-stop shallow well sealing anti-pipe jacking and anti-blowout unsealing process, It is characterized in that In the step 1, the blowout preventer, the blowout preventer pipeline, and the blowout release pipeline are pressure tested to ensure that the connection parts are free of punctures and leaks.

3. According to claim 1, a long-stop shallow well sealing anti-pipe jacking and anti-blowout unsealing process, It is characterized in that In the step 1, the petal-type anti-lifting device is composed of a circular steel body with an inner diameter of 74.5 mm and a 5 mm thick resin, has a buffering function, can extend the impact time to 0.6 s, and has a maximum impact force of 282 kN.

4. According to claim 1, a long-stop shallow well sealing anti-pipe jacking and anti-blowout unsealing process, It is characterized in that In the step 1, the annular steel body and the resin are connected via a connecting piece.

5. According to claim 1, a long-stop shallow well sealing anti-pipe jacking and anti-blowout unsealing process, It is characterized in that In the step 2, a combined blowout prevention device is used, which is a combination of a reverse check valve and a plug valve, to achieve blowout prevention in the downhole and wellhead two-stage oil pipes, and retain the pressure relief space and the circulation channel.

6. The unsealing process for preventing pipe jacking and blowout in a shallow well with a long stop according to claim 1, It is characterized in that In the step 2, the operation is stopped for observation for 4 hours after the blowout, and the following observations are made: the casing pressure drop is 0 MPa, and there is no upward trend, and no toxic or harmful gas is detected at the wellhead.

7. The unsealing process for preventing pipe jacking and blowout in a shallow well sealed for a long time according to claim 1, It is characterized in that In the step 2, if there is no overflow at the wellhead and the tubing is not lifted up, the tubing in the well is pulled out normally. If the pressure relief is ineffective, the tubing in the well is pulled out under pressure through the cooperation of the balanced pressure, the balanced blowout preventer and the hydraulic blowout preventer.

8. According to claim 1, a long-stop shallow well sealing anti-pipe jacking and anti-blowout unsealing process, It is characterized in that In step 4, the tubing string is slowly lifted up, and the increase in load confirms that the bridge plug has been fished out. The movable tubing string is slowly lifted up and lowered until the rubber cartridge is unsealed and continuous overflow occurs in the casing, and it is determined that the fishing is successful.

9. The unsealing process for preventing pipe jacking and blowout in a shallow well sealed for a long time according to claim 1, It is characterized in that In the step 4, the condition of the tubing string in the well is controlled.

10. The unsealing process for preventing pipe jacking and blowout in a shallow well with a long stop according to claim 1, It is characterized in that In step five, during the unsealing process, the working conditions of the blowout preventer and the anti-lifting device are adjusted by real-time monitoring of the wellhead pressure and the tubing pressure to ensure the safety of the unsealing process. During the shutdown observation period after the blowout, the gas in the wellbore is extracted and analyzed to ensure that no toxic or harmful gases are present.