Underwater casing cutting method capable of assisting in sand removal during abrasive cutting processes

Abstract

The application discloses an underwater casing cutting method capable of realizing auxiliary sand discharge in an abrasive cutting process, and comprises the following steps: lowering a cutting device into a casing to be cut and arranging a pressure adjusting assembly; spraying abrasive to the casing through the cutting device; and adjusting the pressure and flow of the casing inner cavity through the pressure adjusting assembly to discharge the sand-carrying liquid generated in the cutting process, so that sand discharge is realized in the cutting process. The underwater casing cutting method capable of realizing auxiliary sand discharge in the abrasive cutting process is applicable to cutting of large-size casings, and compared with conventional methods such as lowering a pump, increasing displacement and increasing viscosity of sand-carrying liquid, the method is simple and easy to implement, is applicable to offshore platform operation, has low construction cost, is stable, efficient and high in operation, and greatly improves cutting construction efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of oil and gas exploitation, and more particularly to an underwater casing cutting method capable of achieving auxiliary sand discharge in the abrasive cutting process. BACKGROUND

[0002] The general discharge of large-size casing abrasive cutting process is 0.5-1 m 3 / min, and the sand ratio is 5%-12%. The abrasive is generally 30-60 mesh garnet or quartz sand, etc. For 9-5 / 8in casing or smaller, the abrasive can be carried to the wellhead by the discharge itself during the cutting process, and the abrasive is not easy to deposit. However, when cutting large-size casings, such as 1338in casings and above, the discharge is 0.5-1 m 3 / min, and the sand ratio is 5%-12%. Under this discharge, the cutting requirement can be met, but under this discharge, the abrasive after cutting cannot be taken out of the wellbore, causing the tool to be buried and unable to be taken out, causing serious consequences. If the discharge is increased or the viscosity of the liquid is increased to meet the sand carrying requirement, the abrasive will be wasted, and the viscosity of the liquid will increase the process and cost of offshore liquid recovery and treatment. A simple auxiliary sand discharge process needs to be researched to meet the sand discharge requirement without increasing the cost.

[0003] According to the conventional downhole sand discharge idea, auxiliary jet pumps / increased discharge or increased sand carrying liquid viscosity are needed. For example, Li Tianci in “Offshore oil well sand removal technology research” proposes to avoid the accumulation of sand particles at the bottom of the well to cause sand burial of the oil layer and the electric submersible pump problem. The jet pump is used to remove the sand accumulated at the bottom of the well together with the electric submersible pump. Part of the high-pressure produced liquid output by the electric submersible pump is used as power liquid to provide power to the jet pump, and the accumulated sand is lifted to the platform wellhead. Wang Xiqin in “Flexible metal oil pump sand discharge and oil production process analysis” mentions that the flexible metal oil pump is used to discharge sand for the wells with large amount of deep sand discharge. Shang Huahua in “Hydraulic sand blasting pump forced sand discharge and oil production technology” uses the hydraulic sand blasting pump to discharge sand. The pressurized power liquid is mainly transported out through the corresponding pipeline by using the pressurizing equipment. The nozzle diameter is further increased to increase the pressure of the power liquid. The power liquid is mixed with the formation liquid to carry the sand in the well to the ground. Gu Yanrong in “Flexible metal pump sand discharge and oil production process” discusses the problems existing in the conventional sand discharge pump sand discharge and oil production. The flexible metal oil pump solves the problem of short service life of the soft seal type floating ring plunger pump plunger. For the oil wells that cannot produce normally due to severe sand discharge and frequent pump inspection, the pump inspection period can be significantly prolonged, and the application effect is remarkable.

[0004] The above sand discharge processes are suitable for conventional downhole sand discharge of oil wells, and there is no related successful case introduction for large-size multi-layer casing abrasive cutting. The conventional sand discharge processes, such as various auxiliary sand discharge pumps, cannot be applied to the sand blasting cutting process of shallow multi-layer casings. SUMMARY

[0005] Therefore, the present application aims to provide an underwater casing cutting method capable of realizing auxiliary sand discharge in the abrasive cutting process, which is suitable for large-size casing cutting, simple and easy to operate, suitable for offshore platform operation, low construction cost, stable operation, high efficiency, and greatly improves the cutting construction efficiency, so as to solve the problems in the prior art.

[0006] According to the present application, an underwater casing cutting method capable of realizing auxiliary sand discharge in the abrasive cutting process is provided, comprising:

[0007] Lowering the cutting device into the casing to be cut and setting a pressure regulating assembly;

[0008] Spraying abrasive materials to the casing through the cutting device;

[0009] Adjusting the pressure and flow of the casing cavity through the pressure regulating assembly to discharge the sand-carrying liquid generated in the cutting process, so as to realize sand discharge in the cutting process.

[0010] Preferably, the pressure regulating assembly comprises:

[0011] The pressure regulating assembly comprises a packer, the packer is arranged above the anchoring device of the cutting device, the packer blocks the casing large annulus formed between the material pipe of the cutting device and the casing, and

[0012] A first backflow hole is opened through the packer, and a first backflow pipe is inserted in the first backflow hole.

[0013] Preferably, the pressure regulating assembly adjusts the pressure and flow of the casing cavity to discharge the sand-carrying liquid generated in the cutting process, so as to realize sand discharge in the cutting process, comprising:

[0014] Discharging the sand-carrying liquid generated in the cutting process through the first backflow pipe.

[0015] Preferably, the pressure regulating assembly further comprises:

[0016] A second backflow hole is opened through the packer, and a second backflow pipe is inserted in the second backflow hole, the second backflow pipe is used in cooperation with the first backflow pipe.

[0017] Preferably, the pressure regulating assembly adjusts the pressure and flow of the casing cavity to discharge the sand-carrying liquid generated in the cutting process, so as to realize sand discharge in the cutting process, comprising:

[0018] The sand-carrying liquid generated during the cutting process is discharged through the first and second return pipes.

[0019] Preferably, when sand precipitation or return pipe blockage occurs, one of the first and second return pipes is pumped into the casing through the liquid receiving pump, and the sand-carrying liquid is discharged through the other return pipe, thereby achieving reverse circulation flushing.

[0020] Preferably, when the liquid is pumped into the casing for a predetermined period of time, and sand is still not successfully discharged, the position of the packer is lowered, and the return pipe of the liquid receiving pump of the two return pipes is lowered relative to the packer.

[0021] Preferably, before the cutting device sprays abrasive material into the casing, the cutting device is first anchored by the anchoring device of the cutting device.

[0022] Preferably, the pressure regulating assembly comprises:

[0023] The pressure regulating assembly comprises a cleaning pipe, and the cleaning pipe is inserted into the casing.

[0024] Preferably, the pressure and flow of the casing cavity are regulated by the pressure regulating assembly to discharge the sand-carrying liquid generated during the cutting process, thereby achieving sand discharge during the cutting process, comprising:

[0025] During the cutting process, the liquid is pumped into the casing cavity through the cleaning pipe, so that the sand-carrying liquid is discharged from the casing annulus.

[0026] Preferably, the lower end of the cleaning pipe is located above the nozzle of the cutting device and is arranged adjacent to the nozzle.

[0027] Advantages:

[0028] The underwater casing cutting method capable of achieving auxiliary sand discharge during abrasive cutting process in the present application can be applied to large-size casings, such as casings greater than or equal to 1338 inches. Compared with conventional methods such as lowering the pump, increasing the displacement, and increasing the viscosity of the sand-carrying liquid, the method is simple and easy to implement, suitable for offshore platform operations, has low construction cost, stable and efficient operation, and greatly improves the cutting construction efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0029] The above and other objects, features and advantages of the present application will become more apparent from the following description of embodiments of the present application with reference to the accompanying drawings.

[0030] Figure 1 A flowchart of the underwater casing cutting method capable of achieving auxiliary sand discharge during abrasive cutting process according to an embodiment of the present application is shown.

[0031] Figure 2 A schematic diagram of an underwater casing cutting operation that enables sand removal during abrasive cutting according to Embodiment 1 of the present invention is shown.

[0032] Figure 3 It shows Figure 2 Enlarged view of part A in the image.

[0033] Figure 4 A schematic diagram of an underwater casing cutting operation that enables sand removal during abrasive cutting according to Embodiment 2 of the present invention is shown.

[0034] Figure 5 A schematic diagram of an underwater casing cutting operation that enables sand removal during abrasive cutting according to Embodiment 3 of the present invention is shown.

[0035] In the diagram: 1. Support flange; 2. Rotary support; 3. Hydraulic motor; 4. Material pipe; 5. Nozzle; 6. Anchoring device; 7. Rotary joint; 8. Sleeve; 91. Packer; 92. First return pipe; 93. Second return pipe; 94. Cleaning pipe. Detailed Implementation

[0036] Various embodiments of the invention will now be described in more detail with reference to the accompanying drawings. In the various drawings, the same elements are indicated by the same or similar reference numerals. For clarity, the various parts in the drawings are not drawn to scale.

[0037] like Figures 1 to 5 As shown, this invention provides an underwater casing cutting method that can assist in sand removal during abrasive cutting. The cutting method uses a cutting device, which includes a support flange 1, a rotary support 2, a hydraulic motor 3, a feed pipe 4, a nozzle 5, and an anchoring device 6. The feed pipe 4 is rotatably mounted on the rotary support 2. The hydraulic motor 3 is installed on the upper end of the rotary support 2, and its shaft is fixedly connected to the upper end of the feed pipe 4. The rotary support 2 is mounted on the support flange 1, and the lower end of the support flange 1 is mounted on an operating platform. The lower end of the feed pipe 4 is rotatably mounted on the anchoring device 6. The nozzle 5 is fixedly connected to and communicates with the feed pipe 4. A rotary joint 7 is provided at the upper end of the feed pipe 4, communicating with the feed pipe 4. The rotary joint 7 is used to connect to an external feed pump. The feed pump (not shown) pumps the abrasive into the feed pipe 4, then transmits it to the nozzle 5, and finally, the abrasive is ejected at high speed by the nozzle 5, striking the inner wall of the casing 8, thereby cutting the casing 8 through continuous high-speed impact.

[0038] It should be noted that, for ease of description, the ejected abrasive is referred to as sand particles in this application, and the discharge of sand particles is referred to as sand discharge.

[0039] The cutting method is introduced below by taking the cutting of an abandoned well in the sea as an example. The sand-carrying liquid is seawater, and the liquid is not limited to seawater, but can also be other fresh water such as lake water, and the specific environment of the abandoned well is used as the criterion. When the pipe diameter of the cutting casing 8 is

[0040] Example one:

[0041] S01), lower the cutting device into the casing 8 to be cut, and set the pressure regulating assembly;

[0042] In this step, the cutting device is inserted into the cutting device, and the support flange 1 is installed on the operation platform, and the pressure regulating assembly is set.

[0043] The pressure regulating assembly includes a packer 91, and the anchor device 6 of the cutting device is provided above the packer 91. The packer 91 blocks the large annulus of the casing 8 formed between the cutting device pipe 4 and the casing 8, and a first backflow hole is formed in the packer 91, and a first backflow pipe 92 is inserted in the first backflow hole. The lower end of the first backflow pipe 92 is exposed from the packer 91, and the upper end of the first backflow pipe 92 extends out of the casing 8. The first backflow pipe 92 can be L-shaped.

[0044] S02), before the cutting device sprays the abrasive to the casing 8, the cutting device pipe 4 is first anchored.

[0045] In this step, after the cutting position of the casing 8 is determined, the lower end of the pipe 4 is anchored to the inner wall of the casing 8 by the anchor device 6, so as to realize the positioning of the nozzle 5. In this way, the positioning of the cutting position can be realized, and accurate cutting can be completed.

[0046] S03), the cutting device sprays the abrasive to the casing 8;

[0047] In this step, the hydraulic motor 3 is started to drive the pipe 4 to rotate, and the pump is started to pump the abrasive into the pipe 4. The abrasive is quickly sprayed from the nozzle 5 to form sand particles.

[0048] S04), the pressure and flow of the casing 8 are adjusted by the pressure regulating assembly, and the sand-carrying liquid generated during the cutting process is discharged, so as to realize sand discharge during the cutting process.

[0049] In this step, during the cutting process, the sand-carrying liquid circulates to the suction inlet of the first backflow pipe 92. The flow cross section of the sand-carrying liquid changes from the large annulus cross section (the annulus formed between the casing 8 and the pipe 4) to the backflow pipe cross section. Specifically, it changes from Due to the sharp decrease in flow area, the water pressure increases rapidly, so that the flow rate increases rapidly, thereby discharging the sand-carrying liquid from the casing 8 through the first backflow pipe 92, and realizing sand discharge during the cutting process.

[0050] In this embodiment, by setting the packer 91 and the first backflow pipe 92 in the casing 8, the sharp change of the flow area is realized to smoothly discharge the sand-carrying liquid generated in the cutting process, so as to realize the sand discharge in the cutting process, and make the casing 8 cutting engineering operation be able to be smoothly implemented.

[0051] Embodiment two:

[0052] S01), the cutting device is lowered into the casing 8 to be cut, and the pressure adjusting assembly is set;

[0053] In this step, the material pipe 4 of the cutting device is inserted into the material pipe 4 to be cut, and the support flange 1 is installed on the operation platform, and the pressure adjusting assembly is set.

[0054] The pressure adjusting assembly comprises a packer 91, the packer 91 is arranged above the anchoring device 6 of the cutting device, the packer 91 blocks the large annulus of the casing 8 formed between the material pipe 4 of the cutting device and the casing 8, and a first backflow hole is opened through the packer 91, and a first backflow pipe 92 is inserted in the first backflow hole. The lower end of the first backflow pipe 92 is exposed from the packer 91, and the upper end of the first backflow pipe 92 extends out of the casing 8, and the first backflow pipe 92 can be L-shaped.

[0055] Further, a second backflow hole is opened through the packer 91, and a second backflow pipe 93 is inserted in the second backflow hole, the lower end of the second backflow pipe 93 is exposed from the packer 91, and the upper end of the second backflow pipe 93 extends out of the casing 8, and the second backflow pipe 93 can be L-shaped, and the second backflow pipe 93 is used in cooperation with the first backflow pipe 92.

[0056] S02), before the cutting device sprays the abrasive to the casing 8, the material pipe 4 of the cutting device is first anchored.

[0057] In this step, after the cutting position of the casing 8 is determined, the lower end of the material pipe 4 is anchored to the inner wall of the casing 8 through the anchoring device 6, so as to realize the positioning of the nozzle 5, and thus the positioning of the cutting position can be realized, and the accurate cutting is completed.

[0058] S03), the cutting device sprays the abrasive to the casing 8;

[0059] In this step, the hydraulic motor 3 is started to drive the material pipe 4 to rotate, and the material pump is started to pump the abrasive into the material pipe 4, the abrasive is quickly sprayed from the nozzle 5 to form the sand particles.

[0060] S04), the pressure and flow of the inner cavity of the casing 8 are adjusted through the pressure adjusting assembly, the sand-carrying liquid generated in the cutting process is discharged, so as to realize the sand discharge in the cutting process.

[0061] In this step, the sand-carrying liquid generated in the cutting process is discharged through the first return pipe 92 and the second return pipe 93. In the cutting process, the sand-carrying liquid circulates to the suction port of the first return pipe 92 and the second return pipe 93, and the flow cross section of the sand-carrying liquid changes from the large annular cross section of the casing 8 (the annular space formed between the casing 8 and the material pipe 4) to the return pipe cross section, specifically from to 2 inches. Due to the sharp reduction in flow area, the water pressure increases rapidly, so that the flow rate increases rapidly, thereby discharging the sand-carrying liquid from the casing 8 through the first return pipe 92 and the second return pipe 93, and achieving sand discharge in the cutting process.

[0062] When sand particles are deposited or the return pipe is blocked, one of the first return pipe 92 and the second return pipe 93 is connected to the liquid pump, and the other return pipe is used to pump liquid into the casing 8, so that the sand-carrying liquid is discharged from the other return pipe (the return pipe not connected to the liquid pump). One of the return pipes is connected to the seawater pump, and a large amount of seawater is pumped in, and the seawater carrying sand flows out through the other return pipe.

[0063] Further, when the liquid pumped into the casing 8 for a predetermined period of time still cannot achieve smooth sand discharge, the position of the packer 91 is lowered, and the return pipe connected to the liquid pump among the two return pipes is lowered relative to the packer 91.

[0064] In this embodiment, by arranging the first return pipe 92 and the second return pipe 93 in the casing 8, on the one hand, the two return pipes can divide and discharge the sand-carrying liquid in the casing 8, and one of the return pipes can be used as a backup to prevent the return pipe from being blocked. On the other hand, when sand particles are deposited or the return pipe is blocked, one of the two return pipes is used to pump liquid and the other is used to discharge liquid, so that the two return pipes are used in combination to achieve the effect of reverse circulation flushing and sand discharge, which can solve the occurrence of special extreme operation failures and effectively ensure the smooth progress of the sand discharge operation in the cutting process of the casing 8.

[0065] Embodiment Three:

[0066] S01), lower the cutting device into the casing 8 to be cut, and arrange the pressure adjusting assembly;

[0067] In this step, the material pipe 4 of the cutting device is inserted into the material pipe 4 to be cut, and the support flange 1 is installed on the operation platform, and the pressure adjusting assembly is arranged.

[0068] In this step, the pressure adjusting assembly includes a cleaning pipe 94, and the cleaning pipe 94 is inserted into the casing 8. The cleaning pipe 94 and the material pipe 4 are arranged in parallel, and the lower port of the cleaning pipe 94 is located between the anchoring device 6 and the nozzle 5 and is arranged close to the nozzle 5.

[0069] S02), before the cutting device sprays abrasive material to the casing 8, first anchor the material pipe 4 of the cutting device.

[0070] In this step, after determining the cutting position of the casing 8, the lower end of the material pipe 4 is anchored to the inner wall of the casing 8 by the anchoring device 6, so as to realize the positioning of the nozzle 5, so as to realize the positioning of the cutting position and complete the accurate cutting.

[0071] S03), spraying abrasive to the casing 8 by the cutting device;

[0072] In this step, the hydraulic motor 3 is started to drive the material pipe 4 to rotate, and the material pump is started to pump the abrasive into the material pipe 4, and the abrasive is quickly sprayed from the nozzle 5 to form sand particles.

[0073] S04), adjusting the pressure and flow of the inner cavity of the casing 8 by the pressure adjusting assembly to discharge the sand-carrying liquid generated in the cutting process, so as to realize sand discharge during the cutting process.

[0074] In this step, during the cutting process, the liquid pump is connected to the cleaning pipe 94, and seawater is pumped into the inner cavity of the casing 8 through the cleaning pipe 94, so that the sand particles are floated from the bottom of the casing 8 and the pressure in the casing 8 is adjusted. A large amount of seawater is circulated to assist sand discharge, so that the sand-carrying liquid is discharged from the annulus of the casing 8.

[0075] During the sand discharge process, the flow rate and discharge pressure of the seawater discharged by the liquid pump can be adjusted according to the sand discharge condition.

[0076] In this embodiment, only the cleaning pipe 94 needs to be arranged, and the sand discharge operation can be successfully carried out by using a large amount of seawater to assist sand discharge, which is simple and easy to operate, has low construction cost and good sand discharge effect.

[0077] The underwater casing cutting method capable of realizing auxiliary sand discharge during the abrasive cutting process in the application can be applied to large-size casings 8, for example, casings 8 with a diameter greater than or equal to 244.5mm. Compared with the conventional methods of lowering the pump, increasing the discharge capacity, and increasing the viscosity of the sand-carrying liquid, the method is simple and easy to operate, suitable for offshore platform operation, has low construction cost, stable operation, and high efficiency, and greatly improves the cutting construction efficiency.

[0078] It is to be understood that the phrases such as first and second, and the like, can refer to different entities or operations without necessarily implying any actual relationship or order between such entities or operations. Moreover, the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can also include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by "comprises... a" does not, without more constraints, exclude the presence of additional identical elements in the process, method, article, or apparatus that comprises the element.

[0079] Finally, it should be noted that the above-mentioned embodiments are merely intended for the purpose of illustration rather than limiting the present application. Based on the above description, those skilled in the art can make other various changes or modifications of the present application. There is no need or attempt to exhaust all the embodiments of the present application. Any changes or modifications derived from the above description should be construed as falling within the scope of the present application.

Claims

1. An underwater casing cutting method capable of achieving assisted sand removal in an abrasive cutting process, characterized in that, The application relates to a cutting device for cutting a casing, comprising: lowering the cutting device into the casing to be cut and arranging a pressure regulating assembly; injecting abrasive material into the casing through the cutting device; regulating the pressure and flow of the casing cavity through the pressure regulating assembly, discharging the sand-carrying liquid generated in the cutting process, and thus achieving sand discharge in the cutting process; arranging the pressure regulating assembly, comprising: the pressure regulating assembly comprises a packer, the packer is arranged above the anchoring device of the cutting device, the packer blocks the casing large annulus formed between the material pipe of the cutting device and the casing, and a first backflow hole is arranged through the packer, and a first backflow pipe is arranged in the first backflow hole; arranging the pressure regulating assembly, further comprising: a second backflow hole is arranged through the packer, and a second backflow pipe is arranged in the second backflow hole, the second backflow pipe is used in cooperation with the first backflow pipe; regulating the pressure and flow of the casing cavity through the pressure regulating assembly, discharging the sand-carrying liquid generated in the cutting process, and thus achieving sand discharge in the cutting process, comprising: discharging the sand-carrying liquid generated in the cutting process through the first backflow pipe and the second backflow pipe; when sand particles deposit or the backflow pipe is blocked, pumping liquid into the casing through one of the first backflow pipe and the second backflow pipe, discharging the sand-carrying liquid through the other backflow pipe, and thus achieving reverse circulation flushing; when the liquid is pumped into the casing for a preset time length, and sand discharge cannot be achieved, the position of the packer is lowered, and the backflow pipe connected with the liquid pump among the two backflow pipes is lowered relative to the packer.

2. The underwater casing cutting method capable of achieving auxiliary sand discharge of an abrasive cutting process according to claim 1, characterized by, regulating the pressure and flow of the casing cavity through the pressure regulating assembly, discharging the sand-carrying liquid generated in the cutting process, and thus achieving sand discharge in the cutting process, comprising: discharging the sand-carrying liquid generated in the cutting process through the first backflow pipe.

3. The method of claim 1, wherein, Before injecting the abrasive material into the casing through the cutting device, the material pipe of the cutting device is first anchored through the anchoring device of the cutting device.

4. The method of claim 1, wherein, arranging the pressure regulating assembly, comprising: the pressure regulating assembly comprises a cleaning pipe, and the cleaning pipe is arranged in the casing.

5. The method of claim 4, wherein the method further comprises, regulating the pressure and flow of the casing cavity through the pressure regulating assembly, discharging the sand-carrying liquid generated in the cutting process, and thus achieving sand discharge in the cutting process, comprising: during the cutting process, pumping liquid into the casing cavity through the cleaning pipe, so that the sand-carrying liquid is discharged from the casing annulus.

6. The method of underwater casing cutting to enable assisted sand flow during abrasive cutting processes according to claim 4 or 5, wherein, the lower end of the cleaning pipe is located above the nozzle of the cutting device and is arranged adjacent to the nozzle.

Images