Method for checking dragging force of in-service submarine pipeline repaired by RTP pipe

Abstract

The invention provides a method for checking dragging force of an in-service submarine pipeline repaired by an RTP pipe, and belongs to the technical field of oil development. Comprising the following steps: preparing test equipment and tools; the traction rope is inserted from the A end to the B end of the test pipeline through the ball serving action; a traction rope is connected with a winch cable, and the cable is pulled from the A end to the B end of the test pipeline through tension equipment; pulling back the winch cable through the winch to drive the RTP pipe to be pulled from the B end to the A end of the test pipeline; pulling all the RTP pipes out of the test pipeline, and observing the deformation condition of the intermediate joint between the adjacent RTP pipes; the dragging force in the test is compared with the dragging force simulated through calculation, whether the calculation model is suitable or not is determined, and the calculation model is checked; and carrying out the dragging test again, verifying the goodness of fit between the adjusted calculation model and the dragging force in the test, and determining the final dragging force. The success rate of in-service submarine pipeline penetrating repair in the small-pipe-diameter RTP pipe can be increased, and the operation cost is reduced.

Description

Technical Field

[0001] The present invention relates to the field of petroleum engineering, and in particular to a method for checking the drag force of an in-service submarine pipeline during RTP pipe repair. Background Art

[0002] As the environment in which submarine pipelines operate becomes increasingly harsh, pipeline failure due to corrosion is becoming increasingly prominent. Finding a more economical and effective repair method for these pipelines is urgent. Small-diameter RTP pipe insertion repair technology is a new, economical and time-saving repair technology. By inserting a small-diameter RTP pipe into a large-diameter steel pipe, it extends the life of the oil field.

[0003] RTP pipe insertion repair technology has been successfully applied overseas on submarine pipelines with few elbows (generally two). However, whether small-diameter RTP pipe insertion technology can be used to repair long, corroded submarine pipelines with multiple elbows (two or more) requires technical verification before offshore construction and simulation tests on land to determine whether the selected RTP pipe can meet the needs of later oilfield development and the passability of RTP pipe in multi-elbow submarine pipelines. Onshore simulation tests can verify the performance of towing equipment, repair RTP pipe, and intermediate joints, and can also correct the towing force model and calibrate the towing force. This technical verification method, which is close to on-site construction conditions, has not been similarly tested or verified in China. Through technical verification and simulation tests, a technical basis and construction reference can be provided for offshore construction.

[0004] In view of this, it is imperative to design a method for verifying the drag force of in-service submarine pipelines using small-diameter RTP pipe insertion for repair. Summary of the Invention

[0005] In view of this, the present invention aims to propose a method for verifying the drag force of RTP pipes used to repair in-service submarine pipelines. The method can effectively verify the performance indicators of RTP pipes before and after insertion, identify the risks that may be encountered in offshore construction in advance, and provide effective solutions. The method also verifies the internal insertion drag force, thereby improving the success rate of small-diameter RTP pipe internal insertion repairs for in-service submarine pipelines, extending the service life of submarine pipelines, and reducing operating costs.

[0006] To achieve the above object, the technical solution of the present invention is implemented as follows: a method for checking the drag force of an in-service submarine pipeline repaired by an RTP pipe, comprising the following steps:

[0007] Step 1: Confirm whether the test pipeline and its surrounding environment meet the conditions for the simulated test and prepare the test equipment and tools. The test equipment and tools include a test RTP pipe, an intermediate joint, a winch, a temporary ball-receiving drum, a pig ball, and a tensioning device. The end where the winch is located is the test pipeline end A, and the end of the test pipeline away from the winch is the test pipeline end B.

[0008] Step 2: Connect the traction rope to the fixing device at the rear of the pig at the end where the winch is located. Inside the test pipeline, insert the traction rope from end A to end B of the test pipeline by launching the ball.

[0009] Step 3: At end A of the test pipeline, connect and secure the traction rope to the winch cable. Use the tensioning device to pull the winch cable connected by the traction rope inside the test pipeline from end A to end B of the test pipeline.

[0010] Step 4: At end B of the test pipeline, disconnect the winch cable and the traction rope, securely connect the RTP pipe to the towing head, and securely connect the winch cable to the towing head. Start the winch, and pull back the winch cable through the winch to pull the RTP pipe from end B to end A of the test pipeline. Adjacent RTP pipe sections are connected using dedicated connectors.

[0011] Step 5: Pull out all the RTP tubes from the test pipeline and observe the deformation of the RTP tubes and the intermediate joints between the RTP tubes;

[0012] Step 6: Compare the test pulling force recorded from the winch with the calculated pulling force to confirm whether the calculation model is suitable and calibrate the calculation model;

[0013] Step 7: Conduct the drag test again to verify the consistency between the adjusted calculation model and the drag force in the test and determine the final drag force.

[0014] Furthermore, in step 1, when confirming whether the test pipeline and its surrounding environment meet the simulated test conditions, if there is any work around the test pipeline that affects the test, the relevant work that affects the test should be stopped before the test is carried out.

[0015] Furthermore, step 2 includes connecting a traction rope to a fixing device at the tail of the cleaning ball at one end where the winch is located. The traction rope has a load-bearing force of 3 tons to 10 tons and is used to pull the winch cable. After ensuring that the traction rope is reliably connected to the cleaning ball, start the water pump, and bring the traction rope to the other end of the experimental pipe section through the ball-launching action. Then, turn off the water pump, remove the ball-launching device, and record the medium flow rate during the traction process.

[0016] Furthermore, step 3 includes fixing the winch cable to the traction rope through a shackle at one end where the winch is located, and using a tension device to pull the traction rope at the B end where the RTP pipe is located to pull the winch cable from the A end to the B end of the test pipeline.

[0017] Furthermore, step 4 includes disconnecting the winch cable and the traction rope at the B end of the test pipeline, connecting the winch cable to the towing head, and connecting the towing head to the RTP tube, manually feeding the starting part of the RTP tube and the connected winch cable into the pipe inlet of the test pipeline, and pulling the winch cable by the winch at the other end, thereby driving the RTP tube to be continuously inserted into the test pipeline, wherein the speed of the RTP tube during the insertion process does not exceed 4 meters / minute to 10 meters / minute. When the RTP tube section in a reel is completely inserted, the insertion is stopped, the existing empty reel is removed, and the empty reel is replaced with a new pipe reel. Using a special intermediate joint crimping device for RTP tubes, the two ends of the intermediate joint are respectively connected to the end of the previous RTP tube and the beginning of the next RTP tube. After the connection is completed, the insertion continues.

[0018] Furthermore, in step 5, the RTP tube is completely pulled out of the test pipeline at a speed not exceeding 4 m / min-10 m / min until the pulling head is pulled out of the test pipeline by a distance greater than 5 m, so as to observe the deformation of the RTP tube and the intermediate joint.

[0019] Furthermore, step 6 includes comparing the drag force in the test with the drag force calculated before the simulation test, confirming whether the calculation model is suitable by considering factors such as the number of elbows, temperature changes, drag speed, and whether there is a spherical flange, and proposing a drag force safety factor and compensation factor to verify the drag force.

[0020] Furthermore, step 7 includes repeating steps 1 to 6 to conduct interleaved tests, comparing the drag force in the test with the calibrated model, and determining the final drag force, thereby completing the drag force calibration.

[0021] Compared with the existing technology, the method for verifying the drag force of an in-service submarine pipeline for RTP pipe repair described in the present invention has the following advantages:

[0022] (1) Through the method of the present invention, the established drag force model was verified, the drag force was calibrated, and technical verification before construction was carried out; through steps 1 to 6, the RTP pipe internal insertion repair technology was systematically verified from the aspects of drag equipment, RTP pipe performance, joint performance, drag force model, construction risks, etc.;

[0023] (2) The method of the present invention can test the performance of RTP pipes before and after simulation tests, predict the risks of offshore construction in advance and propose solutions. A calculation model for the RTP pipe insertion process is proposed, which completely solves the problem of submarine pipeline corrosion.

[0024] (3) The method of the present invention can, on the one hand, verify the feasibility of the technology for repairing in-service submarine pipelines with multiple elbows (more than two) by inserting small-diameter RTP pipes into them; on the other hand, verify whether the produced RTP pipes and intermediate joints meet the construction requirements, and also verify the drag force calculation model. A drag force calculation model that is consistent with the insertion process is also proposed. Finally, a new technology for repairing in-service submarine pipelines can be provided.

[0025] (4) The present invention conducts experimental verification on the RTP pipe insertion repair technology for submarine pipelines with higher corrosion risks. It not only verifies the feasibility of the experimental method, but also provides construction guidance for offshore engineering applications and can significantly reduce the cost of submarine pipeline operation and maintenance in the later stage. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings, which constitute part of the present invention, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. It is possible for a person of ordinary skill in the art to derive other drawings based on the structures shown in these drawings without inventive effort. In the accompanying drawings:

[0027] Figure 1 This is a schematic diagram of a method for verifying the drag force of an in-service submarine pipeline repaired with an RTP pipe according to an embodiment of the present invention. DETAILED DESCRIPTION

[0028] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0029] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0030] The present invention mainly includes the following steps: (1) preparing a test RTP pipe and confirming whether the test pipeline has the working conditions for conducting a simulation test; (2) inserting a traction rope from one end of the test pipeline to the other end through a pipe cleaning ball inside the test pipeline; (3) pulling a winch cable connected by the traction rope inside the test pipeline from one end of the test pipeline to the other end where the RTP pipe is located through a tension device; (4) pulling back the winch cable through the winch to drive the RTP pipe from the other end of the test pipeline to the end where the winch is located, and the RTP pipe sections are connected by intermediate joints; (5) pulling the entire RTP pipe out of the test pipeline to observe the deformation of the RTP pipe and the intermediate joint; and (6) comparing the traction force with the calculated simulation to confirm whether the calculation model is suitable. After the test is completed, on the one hand, it can verify the feasibility of the technology of inserting small-diameter RTP pipes into in-service submarine pipelines with multiple elbows (more than two); on the other hand, it can verify whether the produced RTP pipes and intermediate joints meet the construction requirements, and can also verify the drag force calculation model; finally, it can provide a new technology for repairing in-service submarine pipelines.

[0031] like Figure 1 As shown, the present invention is a method for checking the drag force of an in-service submarine pipeline for repairing an RTP pipe, comprising the following steps:

[0032] Step 1: Confirm that the test pipeline and its surroundings meet the conditions for a simulated test and prepare the test equipment and tools. The test equipment and tools include a test RTP pipe, an intermediate joint, a winch, a temporary ball-receiving barrel, a cleaning ball, and a tensioning device. The end where the winch is located is end A of the test pipeline, and the end of the test pipeline away from the winch is end B of the test pipeline. When confirming that the test pipeline and its surroundings meet the conditions for a simulated test, if any work around the test pipeline that may affect the test is carried out, any work that may affect the test must be stopped before the test can be carried out. Preferably, the RTP pipe has a middle layer of polyester or aramid, and inner and outer layers of PE.

[0033] Step 2: Connect the traction rope to the fixing device at the rear of the pig at the end where the winch is located. Inside the test pipeline, insert the traction rope from end A to end B of the test pipeline by launching the ball.

[0034] Step 3: At end A of the test pipeline, connect and secure the traction rope to the winch cable. Use the tensioning device to pull the winch cable connected by the traction rope inside the test pipeline from end A to end B of the test pipeline.

[0035] Step 4: At end B of the test pipeline, disconnect the winch cable and the traction rope, securely connect the RTP pipe to the towing head, and securely connect the winch cable to the towing head. Start the winch, and pull back the winch cable through the winch to pull the RTP pipe from end B to end A of the test pipeline. Adjacent RTP pipe sections are connected using dedicated connectors.

[0036] Step 5: Pull the RTP tube completely out of the test pipeline and observe the deformation of the RTP tube and the intermediate joint between the RTP tubes. Specifically, pull the RTP tube completely out of the test pipeline at a speed not exceeding 4 m / min-10 m / min to observe the deformation of the RTP tube and the intermediate joint.

[0037] Step 6: Compare the test pulling force recorded from the winch with the calculated pulling force to confirm whether the calculation model is suitable and calibrate the calculation model;

[0038] Step 7: Conduct the drag test again to verify the consistency between the adjusted calculation model and the drag force in the test and determine the final drag force.

[0039] Through the test method described above, the present invention establishes a drag force calculation model by inserting a small-diameter hose (i.e., a hose smaller than the diameter of a submarine pipeline) into a test pipe designed to simulate the original submarine pipeline. This model, in turn, verifies the feasibility of repairing in-service submarine pipelines with multiple elbows (more than two) by inserting a small-diameter RTP hose into the pipeline. Furthermore, it verifies whether the produced RTP pipe and intermediate joints meet construction requirements. Furthermore, a drag force calculation model consistent with the insertion process is proposed. Finally, this provides a novel technology for repairing in-service submarine pipelines.

[0040] The hose used in this test method is preferably a non-metallic RTP pipe (reinforced thermoplastic pipe). It not only has strong internal pressure resistance but also resists corrosion from the produced or reinjected medium and seawater. Furthermore, this hose utilizes axial reinforcement technology to increase its axial tensile strength by 10 times. Furthermore, the long lengths of individual hoses used during production significantly reduce the number of pipe joints used, resulting in low risk and high construction efficiency.

[0041] Based on the basic implementation described above, as a preferred specific test method, the test process mainly includes the following steps: inserting a traction rope and pulling the winch cable from end A to end B of the test pipeline. Specifically, at the end where the winch is located, the traction rope is connected to the fixing device at the tail of the pipe cleaning ball. This traction rope has a load-bearing capacity of 3 tons to 10 tons and is used to pull the winch cable. After ensuring that the traction rope and the pipe cleaning ball are securely connected, the water pump is started and the traction rope is brought to the other end of the test pipe section by a ball-feeding action. The water pump is turned off, the ball-feeding device is removed, and the flow rate of the medium during the traction process is recorded. Preferably, at the end where the winch is located, the winch cable is fixed to the traction rope via a shackle. At end B where the RTP pipe is located, the traction rope is connected to the tail of the tensioning device, the tensioning device (also called the pulling device) is started, and the traction rope is pulled by the tensioning device to pull the winch cable from end A to end B of the test pipeline.

[0042] Furthermore, the winch cable is connected to the RTP tube towing head, and multiple sections of RTP tube are connected using a dedicated joint. Specifically, at the B end of the test pipeline, the winch cable and the towing rope are disconnected, the winch cable is connected to the towing head, and the towing head is connected to the RTP tube. The starting section of the RTP tube and the connected winch cable are manually fed into the pipe inlet of the test pipeline. The winch is started, and the winch cable is pulled by the winch to drive the RTP tube to be inserted into the test pipeline. The speed of the RTP tube insertion process does not exceed 4 meters per minute to 10 meters per minute. When the RTP tube section on a reel is inserted, the insertion is stopped, the existing empty reel is removed, and the empty reel is replaced with a new one. Using a dedicated RTP tube intermediate joint crimping device, the two ends of the intermediate joint are connected to the end of the previous RTP tube section and the beginning of the next RTP tube section, respectively. After the connection is completed, the insertion continues until the towing head is pulled out of the test pipeline by more than 5 meters.

[0043] Furthermore, a large-tonnage winch is used to pull the cable out of the test pipe, driving the RTP pipe from the B end to the A end of the test pipe until the towing head is pulled out of the test pipe by more than 5 meters. The speed during the insertion process does not exceed 4-10 meters per minute.

[0044] In a further specific operation, after the RTP tube is inserted, the RTP tube is completely pulled out from the test pipe section to observe the deformation of the hose and the intermediate joint.

[0045] In a further, specific operation, after the RTP pipe is fully pulled from the test section, the drag force is compared with the pre-test simulation calculation to confirm the suitability of the calculation model. If not, appropriate compensation factors are proposed to calibrate the drag force model. Specifically, the drag force during the test is compared with the drag force calculated before the simulation test. By considering factors such as temperature changes, pulling speed, and the presence of spherical flanges, the suitability of the calculation model is confirmed, and a drag force safety factor and compensation factors are proposed to calibrate the drag force. For the same pipe material, tests can be conducted at different pulling speeds. The comparison of the two pulling forces can determine the impact of pulling speed on the drag force and add a correction factor for the drag force. For the same pipe material, pulling tests can be conducted at different ambient temperatures to determine the impact of ambient temperature on the drag force and add a correction factor for the temperature. For the same pipe material, pulling tests can be conducted at different ambient temperatures but the same pulling speed to determine the impact of ambient temperature on the drag force and add a correction factor for the temperature. For the same pipe material, drag tests can be conducted at different ambient temperatures and the same drag speed to test whether the pipe contains a spherical flange, determine the impact of the spherical flange on the drag force, and add a correction factor for the spherical flange's effect on the drag force. Based on the tests, the calculation model is adjusted, primarily to add different correction factors that affect the drag force.

[0046] Further, based on the calibrated drag force model, perform another RTP pipe drag simulation test until the simulated drag force matches the calculated model. Specifically, repeat steps 1 through 6 to perform interleaved tests. Compare the drag force from the tests to the calibrated model to determine the final drag force, thus completing the drag force calibration.

[0047] From the above, it can be seen that the present invention is a method for verifying the drag force of an in-service submarine pipeline using an RTP pipe. After the test is completed, on the one hand, the feasibility of the technology of repairing in-service submarine pipelines with multiple elbows (more than two) by inserting a small-diameter RTP pipe into the pipe can be verified; on the other hand, it can verify whether the produced RTP pipe and the intermediate joint meet the construction requirements, and the drag force calculation model can also be verified. A drag force calculation model that is consistent with the insertion process is also proposed; finally, a new technology for repairing in-service submarine pipelines can be provided. The present invention conducts experimental verification on the RTP pipe insertion repair technology for submarine pipelines with a higher corrosion risk. It not only verifies the feasibility of the test method, but also provides construction guidance for offshore engineering applications, and can significantly reduce the cost of submarine pipeline operation and maintenance in the later stage.

[0048] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for checking the drag force of an in-service submarine pipeline repaired by an RTP pipe, characterized in that: The following steps are involved: Step 1: Confirm whether the test pipeline and its surrounding environment meet the conditions for the simulated test and prepare the test equipment and tools. The test equipment and tools include a test RTP pipe, an intermediate joint, a winch, a temporary ball-receiving drum, a pig ball, and a tensioning device. The end where the winch is located is the test pipeline end A, and the end of the test pipeline away from the winch is the test pipeline end B. Step 2: Connect the traction rope to the fixing device at the rear of the pig at the end where the winch is located. Inside the test pipeline, insert the traction rope from end A to end B of the test pipeline by launching the ball. Step 3: At end A of the test pipeline, connect and secure the traction rope to the winch cable. Use the tensioning device to pull the winch cable connected by the traction rope inside the test pipeline from end A to end B of the test pipeline. Step 4: At end B of the test pipeline, disconnect the winch cable and the traction rope, securely connect the RTP pipe to the towing head, and securely connect the winch cable to the towing head. Start the winch, and pull back the winch cable through the winch to pull the RTP pipe from end B to end A of the test pipeline. Adjacent RTP pipe sections are connected using dedicated connectors. Step 5: Pull out all the RTP tubes from the test pipeline and observe the deformation of the RTP tubes and the intermediate joints between the RTP tubes; Step 6: Compare the test pulling force recorded from the winch with the calculated pulling force to confirm whether the calculation model is suitable and calibrate the calculation model; Step 7: Conduct the drag test again to verify the consistency between the adjusted calculation model and the drag force in the test and determine the final drag force.

2. The method for verifying the drag force of an in-service submarine pipeline repaired by an RTP pipe according to claim 1, characterized in that: In step 1, when confirming whether the test pipeline and its surrounding environment meet the simulated test conditions, if there is any work around the test pipeline that affects the test, stop the related work that affects the test before conducting the test.

3. The method for verifying the drag force of an in-service submarine pipeline repaired by an RTP pipe according to claim 1, characterized in that: Step 2 includes connecting a traction rope with a load-bearing capacity of 3 to 10 tons to the fixture at the tail of the pig at one end of the winch. This traction rope is used to pull the winch cable. After ensuring that the traction rope and the pig are securely connected, start the water pump and use the ball launcher to bring the traction rope to the other end of the experimental pipe section. Then, turn off the water pump, remove the ball launcher, and record the medium flow rate during the traction process.

4. The method for verifying the drag force of an in-service submarine pipeline repaired by an RTP pipe according to claim 3, characterized in that: Step 3 includes securing the winch cable to the traction rope via a shackle at one end where the winch is located, and using a tensioning device to pull the traction rope at the B end where the RTP pipe is located, thereby pulling the winch cable from the A end to the B end of the test pipeline.

5. The method for verifying the drag force of an in-service submarine pipeline repaired by an RTP pipe according to claim 4, characterized in that: Step 4 includes disconnecting the winch cable and the traction rope at the B end of the test pipeline, connecting the winch cable to the towing head, and connecting the towing head to the RTP tube, manually feeding the starting part of the RTP tube and the connected winch cable into the pipe inlet of the test pipeline, and pulling the winch cable by the winch at the other end, thereby driving the RTP tube to be continuously inserted into the test pipeline, wherein the speed of the RTP tube during the insertion process does not exceed 4 meters / minute to 10 meters / minute. When the RTP tube section in a reel is completely inserted, the insertion is stopped, the existing empty reel is removed, and the empty reel is replaced with a new pipe reel. Using a special intermediate joint crimping device for RTP tubes, the two ends of the intermediate joint are respectively connected to the end of the previous RTP tube and the beginning of the next RTP tube. After the connection is completed, the insertion continues.

6. The method for verifying the drag force of an in-service submarine pipeline repaired by an RTP pipe according to claim 5, characterized in that: In step 5, the RTP tube is completely pulled out of the test pipeline at a speed not exceeding 4 m / min-10 m / min until the pulling head is pulled out of the test pipeline by a distance greater than 5 m, so as to observe the deformation of the RTP tube and the intermediate joint.

7. The method for verifying the drag force of an in-service submarine pipeline repaired by an RTP pipe according to claim 1, characterized in that: Step 6 includes comparing the drag force in the test with the drag force calculated before the simulation test. By considering factors such as the number of elbows, temperature changes, drag speed, and whether there are spherical flanges, the calculation model is confirmed to be suitable, and a drag force safety factor and compensation factor are proposed to verify the drag force.

8. The method for verifying the drag force of an in-service submarine pipeline repaired by an RTP pipe according to claim 7, characterized in that: Step 7 includes repeating steps 1 to 6 to conduct interleaved tests, comparing the drag force in the test with the calibrated model, and determining the final drag force, thereby completing the drag force calibration.

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