A carbon dioxide fracturing post-frac hole-fracture-wellbore coupling paraffin removal device and method

Abstract

The application discloses a kind of carbon dioxide fracturing post-hole crack-wellbore coupling wax removal device and method.The device includes magnetic valve, front cleaning device and claw structure;Claw structure includes main body structure and branch unit, main body structure is from outside to inside in turn inverse scale layer and hydraulic chamber layer, inverse scale layer and hydraulic chamber layer between being equipped with expansion drive cavity and inverse scale drive cavity;Hydraulic chamber layer has axial main flow channel, and main flow channel is equipped with staged shunt valve group, and working fluid is divided into front branch stream and main operation branch stream, and main operation branch stream is secondarily shunted into first drive flow and second drive flow, respectively drives expansion drive cavity and inverse scale drive cavity.The method includes: running into wellbore;Magnetic suction valve is opened after reaching wax removal position, and working fluid is shunted, and front branch stream drives front cleaning device to pretreat, and main operation branch stream drives expansion drive cavity and inverse scale drive cavity to remove wax;The device is lifted and working fluid is recovered.The application realizes hole-crack-wellbore coupling wax removal.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas development technology, and is mainly used for a carbon dioxide fracturing post-fracturing hole-fracture-wellbore coupled wax removal device and method. Background Technology

[0002] In the development of tight oil reservoirs, volumetric fracturing technology is a crucial means to achieve efficient extraction. By modifying the reservoir to create a complex fracture network structure, the flowability of crude oil is improved. The practical effects of volumetric fracturing technology include modifying the fracture environment of tight oil reservoirs, creating favorable extraction conditions, reducing extraction difficulty, shortening penetration distance, and increasing permeability.

[0003] To further improve tight oil recovery and meet the application requirements of carbon capture, utilization, and storage (CCUS) technology, carbon dioxide has been widely used in fracturing operations in tight oil reservoirs. However, the introduction of carbon dioxide also causes wax deposition problems within the reservoir: First, carbon dioxide alters the phase state and temperature and pressure conditions of crude oil, leading to the precipitation of waxy components in pores and fractures; second, temperature and pressure changes within the wellbore also cause wax to deposit and adhere to the inner wall of the tubing; third, as pressure and temperature decrease during production and light components escape, wax in the crude oil gradually precipitates and deposits in the formation, tubing, and gathering / transportation systems.

[0004] This type of wax deposition can cause multiple problems, including clogging reservoir pore throats and fracture channels, reducing crude oil permeability; the wax adhering to the wellbore will reduce the cross-sectional area of ​​the tubing, increase flow resistance, and seriously affect extraction efficiency.

[0005] Given the above problems, existing wax removal technologies are unable to achieve efficient and coordinated cleaning of pores, fractures, and wellbore. Therefore, there is an urgent need for a device and method that can address wax buildup in a coupled manner across pores, fractures, and wellbore to ensure the stable and efficient development of tight oil reservoirs after carbon dioxide fracturing. Summary of the Invention

[0006] This invention aims to solve the problems of wax buildup in reservoir pores, fractures, and well tubing after carbon dioxide fracturing, which leads to reduced oil and gas recovery and increased extraction difficulty. It proposes a coupled pore-fracture-well tubing wax removal device and method after carbon dioxide fracturing.

[0007] The technical solution of this invention is as follows:

[0008] (i) The present invention aims to provide a carbon dioxide fracturing post-fracturing hole-fracture-wellbore coupling dewaxing device. A carbon dioxide fracturing post-fracturing hole-fracture-wellbore coupled wax removal device includes a magnetic suction valve, a pre-cleaning device, and a claw-shaped structure; The claw-shaped structure includes a main structure and at least one branch unit extending radially outward from the main structure. The end of the branch unit is provided with a wax removal head. The main structure is made of diamond-like soft wire armor material, which has both flexibility and strength and can adapt to complex hole and well environment. It is a composite structure, consisting of a reverse scale layer and a hydraulic chamber layer from the outside to the inside. An expansion drive chamber and a reverse scale drive chamber are also provided between the reverse scale layer and the hydraulic chamber layer. The reverse scale layer is composed of multiple reverse scales in a flat and unfolded state. The roots of the reverse scales are rotatably set on the main structure. The hydraulic chamber layer has an axial main channel, the inlet of which is connected to the outlet of a magnetic valve; The main channel is equipped with a graded flow divider valve group to divide the working fluid flow into a pre-branch and a main working branch, and further divide the main working branch into a first driving flow and a second driving flow. An expansion drive chamber, connected to the graded flow divider valve group to receive the first drive flow, is used to generate radial expansion force; a reverse scale drive chamber, connected to the graded flow divider valve group to receive the second drive flow, is used to drive the reverse scale to rotate. The pre-treatment tributary is transported to the pre-treatment cleaning device.

[0009] Among them, the claw-shaped structure is the core execution component of the wax removal operation, integrating thermo-mechanical coordinated wax removal function; the claw-shaped structure is fixedly connected to the tubing and is simultaneously lowered into the wellbore along with the tubing, covering the reservoir channels, fractures and the wax-to-be-removed areas of the wellbore tubing; the magnetic valve is mounted on the outer wall of the tubing and is lowered at a uniform speed to the predetermined position of the perforation section, matching the working area of ​​the claw-shaped structure; the magnetic valve provides precise power control for the operation and is the switch hub for the working fluid.

[0010] The main structure also includes a heating layer disposed inside the reverse scale layer; the heating layer is provided with heating elements distributed in a mesh pattern inside, the heating elements are nickel-chromium alloy heating wires, and the outside is covered with a heat insulation layer to reduce heat loss; the expansion drive cavity and the reverse scale drive cavity are located between the reverse scale layer and the heating layer; the root of the reverse scale is connected to the heating layer through a micro rotating shaft.

[0011] A claw-shaped pressure sensor is installed on the main flow channel; the graded diversion valve group includes a primary main diversion valve and a hydraulic diversion valve; the working fluid flows through the primary main diversion valve and is divided into a 20%-25% pre-branch and a 75%-80% main working branch, with the pre-branch flowing into the pre-cleaning device; the hydraulic diversion valve divides the main working branch in a 7:3 ratio, with the first driving flow accounting for 70%, entering the expansion drive chamber through the first pipeline, and generating radial expansion force through hydraulic expansion; the second driving flow accounting for 30%, entering the reverse scale drive chamber through the second pipeline; The expansion drive chamber is located between the reverse scale layer and the heating layer, and the distance between the expansion drive chamber and the reverse scale layer is less than the distance between the expansion drive chamber and the heating layer; the expansion drive chamber is connected to the hydraulic diverter valve through a first pipeline; the first drive flow enters the expansion drive chamber through the first pipeline; wherein, the first pipeline is a metal pipeline; The reverse scale driving cavity is located between the reverse scale layer and the heating layer, and the distance between the reverse scale driving cavity and the reverse scale layer is greater than the distance between the reverse scale driving cavity and the heating layer; the reverse scale driving cavity and the hydraulic diverter valve are connected through a second pipeline; the second driving flow enters the reverse scale driving cavity through the second pipeline; the second pipeline is a pressure-resistant hose.

[0012] The reverse scale driving chamber is also equipped with a piston, which is connected to a micro rotating shaft via an eccentric wheel. The second driving flow pushes the piston to move axially, and the linear motion is converted into rotational driving force through the eccentric wheel and transmitted to the micro rotating shaft, realizing the state switching of "lying down → standing up". After standing up, the reverse scales continue to rotate with the micro rotating shaft to perform the wax removal work. After the power transmission is completed, the liquid in the driving chamber flows back to the main channel through the return oil pipe with a small flow rate controlled by a one-way valve to avoid pressure overload.

[0013] The magnetic valve is installed on the outer wall of the oil pipe via an adjustable clamp; the inner side of the adjustable clamp is lined with an anti-slip rubber pad to accommodate various specifications of oil pipes; its inlet is equipped with an inlet flow meter and an electromagnetically controlled inlet valve, and has multiple filtration chambers inside; it is also equipped with a timer, a depth sensor and a return pipeline.

[0014] After the tubing is lowered to the predetermined position in the perforation section, the electromagnetically controlled inlet valve opens, and the working fluid injected into the wellbore flows to the inlet of the magnetic valve. After passing through a multi-stage filtration chamber to remove impurities, the working fluid flows through the outlet of the magnetic valve to the inlet of the claw-shaped structure, providing a clean power source for the dewaxing operation and ensuring that the operation starts in sequence.

[0015] The pre-cleaning device includes a high-pressure fan-shaped nozzle group and an annular vortex generating chamber; the pre-cleaning branch is distributed to the high-pressure fan-shaped nozzle group and the annular vortex generating chamber, wherein 10%-15% of the working fluid is supplied to the high-pressure fan-shaped nozzle group and 5% of the working fluid is supplied to the annular vortex generating chamber.

[0016] The high-pressure fan-shaped nozzle assembly includes nozzles evenly distributed on the circumference of the top outer wall and is equipped with an electromagnetic flow regulating valve; the inner wall of the annular vortex generating chamber is equipped with inclined guide vanes controlled by a micro-drive mechanism; the micro-drive mechanism is a micro hydraulic motor. The pre-cleaning device utilizes the hydrodynamic force of the working fluid flow for auxiliary cleaning, thereby achieving the dual functions of impurity removal and cooling.

[0017] The high-pressure fan-shaped nozzle assembly is connected to the primary main flow valve via a branch line. 10%-15% of the working fluid is supplied to the high-pressure fan-shaped nozzle assembly to maintain the corresponding working pressure. After the device is lowered to the predetermined position in the wellbore, the pre-cleaning operation is initiated, and the nozzles spray the working fluid. This spraying process occurs during the pre-cleaning stage, not during the subsequent lifting stage. By forming a fan-shaped water curtain covering the entire circumference of the well wall, it can both flush away the debris generated by the reverse scale and cool the pre-cleaning device to prevent overheating damage. The fluid carrying impurities flows downward along the annular space of the wellbore and eventually collects in the liquid accumulation area at the bottom of the well. The fan-shaped water curtain achieves the dual function of "flushing + cooling," laying the foundation for the subsequent main dewaxing operation of the claw-shaped structure. This is clearly distinguished from the final cleaning stage, where the nozzles are restarted during the tubing lifting process, in terms of timing and functional positioning. This structure integrates cleaning and cooling, reduces additional piping, and the fan-shaped spray can compensate for the blind spots of mechanical cleaning.

[0018] When the working fluid flows through the inclined guide vanes, a spiral vortex is generated. The intensity of the vortex can be adjusted by the angle of the inclined guide vanes. The spiral vortex forms an upward swirling field inside the wellbore, which can engulf fine wax debris with slow settling velocity into the swirling flow. The debris moves upward with the fluid, avoiding deposition in the perforation section. Finally, it is scraped off by the claw-shaped reverse scales and carried into the liquid accumulation area. At the same time, the spiral vortex can also disturb the boundary layer of the well wall, enhance the heat transfer efficiency, and further improve the heating effect of the heating layer. It reduces the secondary deposition of fine particles by utilizing fluid dynamics. It is especially suitable for wellbore in low-permeability reservoirs. Only 5% of the working fluid needs to be diverted. In conjunction with the high-pressure fan-shaped nozzle group, it can form a dual cleaning effect of "flushing + swirling".

[0019] The pre-cleaning device also includes a debris monitoring sensor, a pre-temperature sensor, and a pre-pressure sensor. It also includes a monitoring system; the monitoring system includes a computer and a ground-based remote transmission device; it also includes a computer remote receiver installed on the magnetic valve; the electromagnetic flow regulating valve, the micro hydraulic motor, the debris monitoring sensor, the pre-pressure sensor and the pre-temperature sensor are all transmitted to the computer in sequence through the computer remote receiver and the ground-based remote transmission device, forming a wireless transmission architecture of "ground-based remote transmission device - computer remote receiver - terminal". The debris monitoring sensor can capture changes in the concentration of waxy debris in the fluid after flushing in real time. It monitors waxy debris generated by reverse scaling and nozzle flushing. Its core function is to infer the cleanliness of the wellbore wall from the concentration data. When the debris monitoring sensor detects that the debris concentration continues to decrease to near zero, it can send a signal back to the computer through a remote computer receiver and a ground remote transmission device. Based on this, technicians can issue remote commands to end the lifting and wax scraping operation in advance, which avoids wasting time on ineffective operations and reduces unnecessary friction between the claw structure and the inner wall of the tubing, thus protecting the integrity of the device and the tubing. The electromagnetically controlled inlet valve, timer, inlet flow meter, hydraulic diverter valve, primary main diverter valve, claw-shaped pressure sensor, and nickel-chromium alloy heating wire are all connected to the computer remote receiver and transmitted to the computer via the ground remote transmission device. The nickel-chromium alloy heating wire is wired to the computer remote receiver via a high-temperature resistant wire; the heating power can be remotely adjusted by the computer, and it can stably heat to the optimal temperature range for wax removal during operation, melting the residual wax on the well wall and the wax scraped off by the reverse scales through heat conduction.

[0020] The present invention aims to propose a post-coupling dewaxing method for borehole-fracture-wellbore after carbon dioxide fracturing. A post-CO2 fracturing hole-fracture-wellbore coupled wax removal method, using the above-mentioned CO2 fracturing post-fracture hole-fracture-wellbore coupled wax removal device, is described in the following steps: When lowering into the wellbore, the reverse scales are in a flat position to reduce downward resistance and avoid rubbing against the well wall until they are lowered into the wellbore to the predetermined dewaxing position; When the dewaxing position is reached, the magnetic suction valve is opened, and the working fluid flows into the magnetic suction valve. After passing through the graded diversion valve, it is divided into a 20%-25% pre-branch and a 75%-80% main working branch. The preceding tributary drives the preceding cleaning device to pre-treat the wellbore; 70% of the main working branch flow is diverted to the expansion drive cavity to generate radial expansion force, and 30% is diverted to the reverse scale drive cavity to drive the reverse scale to rotate. During the wax removal operation, the reverse scale unfolds outward, extends into the perforation gap, and continuously rotates to scrape off the surface wax. The device is lifted up; the working fluid is recovered through the return pipeline to complete the operation.

[0021] The technical effects of this invention are as follows: (1) To solve the problem that existing technologies are difficult to clean reservoir pores, fractures and wellbore in a coordinated manner, a magnetic valve and a claw structure are used to work together to achieve coupled wax removal of reservoir pores, fractures and wellbore tubing, thus achieving coupled wax removal of the whole area; avoiding local wax residue from clogging pore throats or reducing tubing cross-section, thus ensuring tight oil extraction efficiency; at the same time, a computer remote receiver connected to a computer is equipped on the upper part of the magnetic valve to achieve automated control of the entire operation. (2) The three mechanisms of “thermal melting-mechanical scraping-fluid diversion” are integrated. The heating layer softens the wax, the reverse scales precisely scrape the wax in the pores, and the annular vortex generation cavity prevents the deposition of fine wax chips. The three mechanisms work together to improve the thoroughness of wax removal and significantly reduce the amount of residue compared with traditional technology. (3) The entire process is automated by relying on the wireless transmission architecture. The sensor provides real-time data feedback, the computer dynamically adjusts the parameters, and the debris monitoring sensor can also intelligently terminate invalid operations, reducing labor costs and safety risks. The adjustable clamp is compatible with multiple specifications of oil pipes, and the return pipeline recovers the working fluid, reducing equipment and consumable costs. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of the carbon dioxide fracturing post-fracturing hole-fracture-wellbore coupling dewaxing device of the present invention.

[0023] Figure 2 This is a schematic diagram of the area inside the claw gap.

[0024] Figure 3 This is a diagram illustrating the upward scraping of wax.

[0025] Reference numerals: 1. Computer; 2. Ground-based remote transmission device; 3. High-pressure fan-shaped nozzle assembly; 4. Pre-positioned temperature sensor; 5. Miniature hydraulic motor; 6. Computer remote receiver; 7. Timer; 8. Electromagnetically controlled inlet valve; 9. Multi-stage filtration chamber; 10. Return pipeline; 11. Magnetic valve; 12. High-temperature resistant wire; 13. Heating layer; 14. Miniature rotating shaft; 15. Reverse scale layer; 16. Hydraulic chamber; 17. Hydraulic diverter valve; 18. 19. Claw-shaped structure; 20. Primary main diversion valve; 21. Pressure sensor; 22. Depth sensor; 23. Inlet flow meter; 24. Adjustable clamp; 25. Annular vortex generating chamber; 26. Inclined guide vane; 27. Electromagnetic flow regulating valve; 28. Pre-pressure sensor; 29. ​​Check valve; 30. Eccentric wheel; 31. Reverse scale; 32. Piston; 33. Reverse scale drive chamber; 34. Expansion drive chamber; 35. Nozzle; 36. Debris monitoring sensor. Detailed Implementation

[0026] Example 1: A carbon dioxide fracturing post-fracturing hole-fracture-wellbore coupled wax removal device, characterized in that it includes a magnetic suction valve 11, a pre-cleaning device, and a claw-shaped structure 18; The claw-shaped structure 18 includes a main structure and at least one branch unit extending radially outward from the main structure. The end of the branch unit is provided with a wax removal head. The main structure is a composite structure, consisting of a reverse scale layer 15 and a hydraulic chamber 16 from the outside to the inside. An expansion drive chamber 33 and a reverse scale drive chamber 32 are also provided between the reverse scale layer 15 and the hydraulic chamber 16. The reverse scale layer 15 is composed of multiple reverse scales 30 in a flat and unfolded state. The roots of the reverse scales 30 are rotatably mounted on the main structure. The hydraulic chamber 16 has an axial main channel, and the inlet of the main channel is connected to the outlet of the magnetic valve 11. The main channel is equipped with a graded flow divider valve group to divide the working fluid flow into a pre-branch and a main working branch, and further divide the main working branch into a first driving flow and a second driving flow. The expansion drive chamber 33 is connected to the graded flow divider valve group to receive the first drive flow and is used to generate radial expansion force; the reverse scale drive chamber 32 is connected to the graded flow divider valve group to receive the second drive flow and is used to drive the reverse scale 30 to rotate. The pre-treatment tributary is transported to the pre-treatment cleaning device.

[0027] The specific implementation process of this embodiment is as follows: When lowering into the wellbore, the reverse scale 30 is in a flat position to reduce downward resistance and avoid rubbing against the well wall until it is lowered into the wellbore to the predetermined dewaxing position; When the dewaxing position is reached, the magnetic suction valve 11 is opened, and the working fluid flows into the magnetic suction valve 11. After passing through the graded diversion valve, it is divided into a 20%-25% pre-branch and a 75%-80% main working branch. The preceding tributary drives the preceding cleaning device to pre-treat the wellbore; 70% of the main working branch flow is diverted to the expansion drive chamber 33 to generate radial expansion force, and 30% is diverted to the reverse scale drive chamber 32 to drive the reverse scale 30 to rotate. During the wax removal operation, the reverse scale 30 unfolds outward, extends into the perforation gap, and continuously rotates to scrape off the surface wax. The device is lifted up; the working fluid is recovered through the return fluid pipeline 10 to complete the operation.

[0028] Example 2, based on Example 1, further includes:

[0029] The main structure also includes a heating layer 13 disposed inside the reverse scale layer 15; the heating layer 13 is provided with heating elements distributed in a mesh pattern inside, the heating elements are nickel-chromium alloy heating wires, and the outside is covered with a heat insulation layer to reduce heat loss; the expansion drive cavity 33 and the reverse scale drive cavity 32 are located between the reverse scale layer 15 and the heating layer 13; the root of the reverse scale 30 is connected to the heating layer 13 through a micro rotating shaft 14; When the device is lowered into the wellbore, the reverse scales 30 lie flat to reduce downward resistance and avoid rubbing against the well wall. During the wax removal operation, the reverse scales 30 unfold outward, extend into the perforation gap, and continuously rotate to scrape off the surface wax.

[0030] Example 3, based on Example 2, further includes:

[0031] A claw-shaped pressure sensor 20 is provided on the main channel; the graded diversion valve group includes a primary main diversion valve 19 and a hydraulic diversion valve 17; the working fluid flows through the primary main diversion valve 19 and is divided into a 20%-25% pre-branch and a 75%-80% main working branch, with the pre-branch flowing into the pre-cleaning device; of which, 10%-15% is supplied to the high-pressure fan-shaped nozzle group 3 and 5% is supplied to the annular vortex generating chamber 24. The hydraulic diverter valve 17 divides the main working branch flow in a 7:3 ratio. The first driving flow accounts for 70% and enters the expansion driving chamber 33 through the first pipeline, generating radial expansion force through hydraulic expansion. The second driving flow accounts for 30% and enters the reverse scale driving chamber 32 through the second pipeline.

[0032] The expansion drive cavity 33 is located between the reverse scale layer 15 and the heating layer 13, and the distance between the expansion drive cavity 33 and the reverse scale layer 15 is less than the distance between the expansion drive cavity 33 and the heating layer 13; the expansion drive cavity 33 is connected to the hydraulic diversion valve 17 through a first pipeline; the first drive flow enters the expansion drive cavity 33 through the first pipeline; wherein, the first pipeline is a metal pipeline.

[0033] The expansion drive chamber 33 is located between the reverse scale layer 15 and the heating layer 13, and closer to the reverse scale layer 15. It is connected to the hydraulic diversion valve 17 through a first pipeline. After receiving the first drive flow, it quickly fills the chamber to form working pressure. Through hydraulic expansion, it generates radial thrust, driving multiple branch units of the claw-shaped structure 18 to extend into the perforation gap. The branch unit has a small auxiliary flow channel, which allows the liquid to reach the end of the unit and push the arc-shaped wax removal head to fit tightly against the gap wall. After the pushing action is completed, some of the liquid returns to the main channel of the inner hydraulic chamber 16 through the return thin tube to maintain the pressure balance in the chamber. A pressure sensor 20 is installed at the top of the chamber, which can wirelessly feed back pressure data to the computer 1 in real time.

[0034] The reverse scale driving cavity 32 is located between the reverse scale layer 15 and the heating layer 13, and the distance between the reverse scale driving cavity 32 and the reverse scale layer 15 is greater than the distance between the reverse scale driving cavity 32 and the heating layer 13; the reverse scale driving cavity 32 is connected to the hydraulic diversion valve 17 through a second pipeline; the second driving flow enters the reverse scale driving cavity 32 through the second pipeline; the second pipeline is a pressure-resistant hose. The reverse scale driving cavity 32 is also provided with a piston 31, and the piston 31 is connected to the miniature rotating shaft 14 through an eccentric wheel 29.

[0035] Each reverse scale 30 corresponds to an independent drive chamber. After receiving the second drive flow, it pushes the piston 31 to move axially. The linear motion is converted into rotational driving force by the eccentric wheel 29 and transmitted to the miniature rotating shaft 14 of the reverse scale 30, realizing the state switch of "lying down → standing up". After standing up, the reverse scale 30 continues to rotate with the miniature rotating shaft 14. After the power transmission is completed, the liquid in the drive chamber flows back to the main channel through the return oil pipe controlled by the one-way valve 28 with a small flow rate to avoid pressure overload.

[0036] Example 4, based on Example 3, further includes: the magnetic suction valve 11 is installed on the outer wall of the oil pipe via an adjustable clamp 23; the inner side of the adjustable clamp 23 is lined with an anti-slip rubber pad to adapt to various specifications of oil pipes; its inlet is equipped with an inlet flow meter 22 and an electromagnetically controlled inlet valve 8, and has a multi-stage filtration chamber 9 inside; and is equipped with a timer 7, a depth sensor 21 and a return pipeline 10.

[0037] After the tubing is lowered to the predetermined position in the perforation section, the electromagnetically controlled inlet valve 8 opens, and the working fluid injected into the wellbore flows to the inlet of the magnetic valve 11. After passing through the multi-stage filter chamber 9 to remove impurities, the working fluid flows through the outlet of the magnetic valve 11 to the inlet of the claw-shaped structure 18, providing a clean power source for the dewaxing operation and ensuring that the operation starts in sequence.

[0038] Example 5, based on Example 4, further includes: the pre-cleaning device includes a high-pressure fan-shaped nozzle group 3 and an annular vortex generating chamber 24; the pre-branch is distributed to the high-pressure fan-shaped nozzle group 3 and the annular vortex generating chamber 24, wherein 10%-15% of the working fluid is supplied to the high-pressure fan-shaped nozzle group 3 and 5% of the working fluid is supplied to the annular vortex generating chamber 24.

[0039] The high-pressure fan-shaped nozzle assembly 3 includes nozzles 34 evenly distributed on the outer circumference of the top wall and equipped with an electromagnetic flow regulating valve 26. The nozzles 34 are made of erosion-resistant ceramic material and are distributed along the outer circumference of the pre-mounted device. They are connected to the inner hydraulic chamber 16 of the claw-shaped structure 18 through a diversion pipeline. After the device is lowered to the predetermined position in the wellbore, the pre-cleaning operation is started, and the nozzles 34 spray working fluid. By forming a fan-shaped water curtain covering the entire circumference of the well wall, it can both flush away the debris generated by the reverse scales 30 and cool the pre-cleaning device to prevent overheating damage. The fluid carrying impurities flows downward along the annular space of the wellbore and finally collects in the liquid accumulation area at the bottom of the well. The fan-shaped water curtain achieves the dual function of "flushing + cooling", laying the foundation for the subsequent main wax removal operation of the claw-shaped structure 18. This is clearly distinguished from the final cleaning stage, where the nozzles 34 are restarted during the lifting process, in terms of timing and functional positioning. The fan-shaped spray can compensate for the dead corners of mechanical cleaning and realize the integration of cleaning and cooling, reducing additional pipelines.

[0040] The inner wall of the annular vortex generating chamber 24 is equipped with inclined guide vanes 25 controlled by a micro-drive mechanism, which is a micro-hydraulic motor 5. When the working fluid flows through the inclined guide vanes 25, a spiral vortex is generated. The intensity of the vortex can be adjusted by the angle of the inclined guide vanes 25, and the rotation of the inclined guide vanes 25 is driven by the micro-hydraulic motor 5 to achieve remote control. The vortex forms an upward swirling field within the wellbore, which can engulf fine wax debris with slow settling velocity into the swirling flow, causing it to move upward with the fluid and preventing it from depositing in the perforation section. This debris is ultimately scraped away by the reverse scales 30 of the subsequent claw-shaped structure 18 and carried into the fluid accumulation area. Simultaneously, the spiral vortex can also disturb the wellbore boundary layer, enhancing heat transfer efficiency and further improving the heating effect of the heating layer 13. This structure utilizes fluid dynamics to reduce secondary deposition of fine particles, making it particularly suitable for low-permeability reservoir wellbores. Only 5% of the working fluid needs to be diverted, and in conjunction with the high-pressure fan-shaped nozzle group 3, it can form a dual cleaning effect of "flushing + swirling".

[0041] Example 6, based on Example 5, further includes: the pre-cleaning device also includes a debris monitoring sensor 35, a pre-temperature sensor 4, and a pre-pressure sensor 27.

[0042] Example 7, based on Example 6, further includes a monitoring system; the monitoring system includes a computer 1 located on the ground and a ground remote transmission device 2; it also includes a computer remote receiver 6 installed on the magnetic valve 11; the electromagnetic flow regulating valve 26, the micro hydraulic motor 5, the debris monitoring sensor 35, the pre-pressure sensor 27, and the pre-temperature sensor 4 are all transmitted to the computer 1 sequentially through the computer remote receiver 6 and the ground remote transmission device 2, forming a wireless transmission architecture of "ground remote transmission device 2 - computer remote receiver 6 - terminal"; The electromagnetically controlled inlet valve 8, timer 7, inlet flow meter 22, hydraulic diverter valve 17, primary main diverter valve 19, and claw-shaped pressure sensor 20 are all wirelessly connected to the computer 1. The nickel-chromium alloy heating wire is wired to the computer 1 via a high-temperature resistant wire 12; the heating power can be remotely adjusted by the computer 1, and the heating is stably maintained at the optimal temperature range for wax removal during operation, melting the residual wax on the well wall and the wax scraped off by the reverse scale 30 through heat conduction.

[0043] The specific implementation process of this embodiment is as follows:

[0044] First, the claw-shaped structure 18 is fixedly connected to the tubing. The magnetic valve 11 and the pre-cleaning device are assembled on the outer wall of the tubing and are simultaneously lowered into the wellbore along with the tubing. The computer 1 monitors the lowering position and the wax deposition status of the well wall in real time through the depth sensor 21, the pre-temperature sensor 4, and the pre-pressure sensor 27, and presets the diversion ratio of the primary main diversion valve 19 and the hydraulic diversion valve 17. Until the magnetic valve 11 descends at a constant speed with the tubing to the predetermined position of the perforation section, the claw-shaped structure 18, which is fixedly connected to the tubing, simultaneously covers the reservoir channels, fractures, and the area of ​​the tubing to be cleaned of wax. The pre-cleaning device at the front end of the device is precisely aligned with the section of the wellbore to be pre-treated.

[0045] When the timer 7 of the magnetic valve 11 reaches the preset time or the computer 1 issues a command, the electromagnetically controlled inlet valve 8 automatically opens, and the working fluid flows into the hydraulic chamber 16 of the claw structure 18. It is then diverted to the pre-cleaning device and the claw structure 18 according to a preset ratio. The ground computer 11 displays in real time: flow data (including the monitoring data of the inlet flow meter 22 at the inlet of the magnetic valve 11), pressure data (including the monitoring data of the pressure sensor 20 in the inner hydraulic chamber 16 of the claw structure 18 and the monitoring data of the pre-pressure sensor 27 of the pre-cleaning device), and the waxy debris concentration data captured in real time by the debris monitoring sensor 35.

[0046] The pre-cleaning device is activated first, and the nozzles 34 of the high-pressure fan-shaped nozzle group 3 spray flushing fluid. The annular vortex generating chamber 24 generates swirling flow, simultaneously cleaning the loose wax layer and fine debris on the well wall. Subsequently, the expansion drive chamber 33 of the claw-shaped structure 18 receives the first drive flow. After the expansion drive chamber 33 is quickly filled, it forms working pressure. The radial thrust is generated through hydraulic expansion, driving multiple branch units of the claw-shaped structure 18 to extend into the perforation gap. The reverse scale drive chamber 32 receives the second drive flow, driving the reverse scale 30 to stand up and rotate. The heating layer 13 starts to heat up, working together to remove the wax in the hole and gap.

[0047] Finally, the ground equipment starts the lifting procedure. The claw-shaped structure 18, which is fixedly connected to the tubing, moves upward synchronously with the tubing. The reverse scales 30 on the outer layer move upward to scrape off the residual wax on the inner wall of the tubing. The nozzles 34 of the high-pressure fan-shaped nozzle group 3 at the front end of the device start synchronously and spray working fluid to flush the residual wax debris in the wellbore. At this time, the debris monitoring sensor 35 enters the high-frequency monitoring state. The debris monitoring sensor 35 transmits the real-time collected debris concentration data to the ground computer 11 through the computer remote receiver 6 and the ground remote transmission device 2. The ground computer 11 performs multi-dimensional correlation analysis on the waxy debris concentration data collected in real time by the debris monitoring sensor 35, the lifting depth fed back by the depth sensor 21, the flushing flow data related to the inlet flow meter 22 and the electromagnetic flow regulating valve 26, and the pressure parameters monitored by the pressure sensor 20 and the pre-pressure sensor 27, and automatically generates a "preliminary assessment of wax removal effect" report. This report intuitively reflects the thoroughness of wax removal at different well depths and helps technicians to more accurately judge whether the overall wax removal effect meets the subsequent operation requirements of tight oil reservoir development.

[0048] The remaining working fluid in the main channel is recovered through the return fluid pipeline 10. The computer 1 records the data throughout the process and generates a dewaxing report, thus completing the comprehensive dewaxing of the hole-fracture-wellbore.

[0049] Specific application examples

[0050] First, experimental preparations are conducted, ensuring that all components of the entire device are fully connected and functioning correctly. The high-pressure fan-shaped nozzle group 3 of the pre-cleaning device is inspected (confirming that nozzle 34 is undamaged and that the diversion pipeline is smoothly connected to the hydraulic chamber 16), and the annular vortex generating chamber 24 (verifying the rotational flexibility of the inclined guide vane 25 and the secure wireless connection of the micro hydraulic motor 5). Simultaneously, the activity state of the reverse scale 30, the energized heating function of the heating layer 13 (ensuring stable temperature rise to the optimal dewaxing range), the sensitivity of the pressure sensor 20, and the cleanliness of the filter screen in the multi-stage filtration chamber 9 and the switching response speed of the electromagnetically controlled inlet valve 8 are adjusted. Furthermore, the working fluid is injected into the wellbore, and the inlet flow meter 22 and the proportion of the primary main diversion valve 19 are calibrated (preset the total diversion of the pre-cleaning device to 20%-25%, with 10%-15% flowing to the high-pressure fan-shaped nozzle group 3 and 5% flowing to the annular vortex generating chamber 24).

[0051] The device is then lowered and positioned. The claw-shaped structure 18 is fixed to the oil pipe with a high-strength buckle. The magnetic valve 11 is assembled to the outer wall of the oil pipe with an adjustable clamp 23 and is located above the claw-shaped structure 18. The pre-cleaning device is installed at the front end and fixed to the oil pipe.

[0052] The ground-based remote transmission device 2 is connected to the computer 1. The electromagnetic flow regulating valve 26, the micro hydraulic motor 5, the debris monitoring sensor 35, the pre-pressure sensor 27, and the pre-temperature sensor 4 are all transmitted to the computer 1 sequentially via the computer remote receiver 6 and the ground-based remote transmission device 2. The electromagnetically controlled inlet valve 8, the timer 7, the inlet flow meter 22, the hydraulic diverter valve 17, the primary main diverter valve 19, the claw-shaped pressure sensor 20, and the nickel-chromium alloy heating wire are all connected to the computer remote receiver 6 and transmitted to the computer 1 via the ground-based remote transmission device 2. The nickel-chromium alloy heating wire is wired to the computer remote receiver 6 via a high-temperature resistant wire 12, thus realizing data interaction with the ground-based remote transmission device 2.

[0053] Start the ground lifting equipment and slowly lower the tubing and the entire set of equipment into the simulated well. Computer 1 monitors the lowering position in real time through depth sensor 21 until the magnetic valve 11 reaches the preset perforation section position. At this time, the claw structure 18 completely covers the reservoir pores, fractures and the area of ​​the well to be dewaxed. The pre-cleaning device is aligned with the well pretreatment section, the lowering is stopped and the tubing is fixed.

[0054] Next, parameter settings and startup are performed. Input the dewaxing parameters on computer 1: magnetic valve 11 trigger delay time (to ensure stable positioning of the device), target temperature of heating layer 13, rotation speed of reverse scale 30, dewaxing duration, etc. After the timer 7 on magnetic valve 11 reaches the preset time, the electromagnetically controlled liquid inlet valve 8 automatically opens, and the working fluid enters the hydraulic chamber 16 through magnetic valve 11.

[0055] Entering the collaborative dewaxing stage, the working fluid in the hydraulic chamber 16 is divided according to a preset ratio: 20%-25% of the fluid is delivered to the pre-cleaning device; of which 10%-15% drives the high-pressure fan-shaped nozzle group 3 to spray the working fluid, forming a fan-shaped water curtain covering the entire circumference of the well wall, washing away loose wax on the surface of the well barrel; 5% of the fluid enters the annular vortex generating chamber 24, driving the inclined guide vane 25 to rotate and generate a spiral vortex, entraining fine wax debris into the vortex field to avoid deposition. At the same time, the remaining 75%-80% of the working fluid is distributed in a 7:3 ratio through the hydraulic diversion valve 17, with 70% of the working fluid entering the expansion drive chamber 33, driving the branch unit to extend into the perforation fracture and push the arc-shaped dewaxing head to adhere to the fracture wall; 30% of the working fluid enters the reverse scale drive chamber 32, driving the reverse scale 30 to switch from a flat state to an upright rotating state, which, together with the heat of the heating layer 13, achieves collaborative dewaxing through mechanical scraping and thermal melting.

[0056] In the parameter control during the collaborative dewaxing stage, the data from the debris monitoring sensor 35 can also indirectly assist in optimizing the flushing intensity of the high-pressure fan-shaped nozzle group 3. For example, when the debris monitoring sensor 35 detects a sudden increase in debris concentration at a certain stage, the computer 1 can determine that there is concentrated wax debris falling off in that area. Then, by adjusting the electromagnetic flow regulating valve 26 of the pre-cleaning device, the working fluid supply ratio of the high-pressure fan-shaped nozzle group 3 can be appropriately increased (fine-tuned within a preset range of 10%-15%) to enhance the flushing capacity of the fan-shaped water curtain, ensuring that the concentrated wax debris can be carried away in time, avoiding secondary deposition in the wellbore, and further ensuring the continuity and thoroughness of the dewaxing operation.

[0057] During the final stage of the operation, after the wax removal has reached the preset time, computer 1 issues a command to close the electromagnetically controlled inlet valve 8 and the heating layer 13, and the wellbore injection stops. The remaining working fluid in the hydraulic chamber 16 and the pre-cleaning device is recovered to the ground through the return fluid pipeline 10 located at the bottom of the magnetic suction valve 11. Then, the hoisting equipment is started to lift the oil pipe, and the reverse scale 30 moves upward to scrape off the residual wax on the inner wall of the oil pipe. The high-pressure fan-shaped nozzle group 3 is simultaneously restarted to flush out the residual debris in the wellbore.

[0058] Finally, the effect was tested and the device was reset. The reservoir core and tubing were removed, and the amount of wax residue in the channels and fractures and the cleanliness of the tubing inner wall were tested to evaluate the wax removal efficiency. Computer 1 automatically generated a wax removal report containing data such as pressure curve (data from pressure sensor 20), temperature change (data from pre-temperature sensor 4), and flow distribution (data from inlet flow meter 22). The device components were disassembled, and residual wax debris was cleaned from the reverse scale 30, high-pressure fan-shaped nozzle group 3 (including nozzle 34) and filter chamber. The pipeline sealing was checked, and worn parts were replaced to prepare for the next experiment.

[0059] In addition, the claw-shaped structure 18 can also be replaced with a titanium alloy woven mesh material, which also has flexibility and high strength, and has better resistance to corrosion from complex media inside the wellbore, and can meet the needs of long-term wax removal operations; at the same time, the material of the reverse scale 30 is also replaced with titanium alloy to ensure scraping strength and service life; the nickel-chromium alloy heating wire of the heating layer 13 can be replaced with a graphene heating film. The graphene heating film has the advantages of faster heating speed and more uniform heat distribution, which can shorten the wax softening time, and can also be connected to the computer 1 through the high-temperature resistant wire 12 without changing the remote temperature control function.

[0060] The original magnetic valve 11 can be replaced with a hydraulically driven valve, eliminating the magnetic structure and controlling the switch via a hydraulic push rod. This adapts to magnetically sensitive wellbore environments while retaining the core configuration of the multi-stage filtration chamber 9, timer 7, and electromagnetically controlled inlet valve 8. This ensures precise control of the working fluid filtration effect and the switching timing. Only the power source is switched from magnetic to hydraulic, with hydraulic power provided through the working fluid branch of the hydraulic chamber 16, eliminating the need for an additional power system.

[0061] The power source of the pre-cleaning device can also be adjusted. The micro hydraulic motor 5 of the original annular vortex generating chamber 24 can be replaced with a pneumatic motor. If the work site has compressed air supply conditions, the pneumatic motor has a simpler structure, lower maintenance costs, and can be remotely controlled through a computer remote receiver 6 to maintain the angle adjustment function of the tilting guide vane 25, ensuring the spiral vortex generation effect and not affecting the entrainment and anti-deposition of fine wax chips.

Claims

1. A carbon dioxide fracturing post-fracturing hole-fracture-wellbore coupled wax removal device, characterized in that, Includes a magnetic valve (11), a pre-cleaning device, and a claw-shaped structure (18); The claw-shaped structure (18) includes a main structure and at least one branch unit extending radially outward from the main structure. The end of the branch unit is provided with a wax removal head. The main structure is a composite structure, consisting of a reverse scale layer (15) and a hydraulic chamber (16) from the outside to the inside. An expansion drive chamber (33) and a reverse scale drive chamber (32) are also provided between the reverse scale layer (15) and the hydraulic chamber (16). The reverse scale layer (15) is composed of multiple reverse scales (30) in a flat and unfolded state. The roots of the reverse scales (30) are rotatably mounted on the main structure. The hydraulic chamber (16) has an axial main channel. The inlet of the main channel is connected to the outlet of the magnetic valve (11). The main channel is equipped with a graded flow divider valve group to divide the working fluid flow into a pre-branch and a main working branch, and further divide the main working branch into a first driving flow and a second driving flow. The expansion drive chamber (33) is connected to the graded flow divider valve group to receive the first drive flow and is used to generate radial expansion force; The reverse scale driving chamber (32) is connected to the graded flow divider valve group to receive the second driving flow for driving the reverse scale (30) to rotate; The pre-treatment tributary is transported to the pre-treatment cleaning device.

2. The carbon dioxide fracturing post-fracturing hole-fracture-wellbore coupled wax removal device according to claim 1, characterized in that, The main structure also includes a heating layer (13) disposed inside the reverse scale layer (15); the heating layer (13) is provided with heating elements distributed in a mesh pattern inside, the heating elements are nickel-chromium alloy heating wires, and the outside is covered with a heat insulation layer; the expansion drive cavity (33) and the reverse scale drive cavity (32) are located between the reverse scale layer (15) and the heating layer (13); the root of the reverse scale (30) is connected to the heating layer (13) through a micro rotating shaft (14).

3. The carbon dioxide fracturing post-fracturing hole-fracture-wellbore coupled wax removal device according to claim 1, characterized in that, A claw-shaped pressure sensor (20) is provided on the main channel; the graded diversion valve group includes a primary main diversion valve (19) and a hydraulic diversion valve (17); the working fluid flows through the primary main diversion valve (19) and is divided into a pre-branch and a main working branch, the pre-branch flows into the pre-cleaning device; the main working branch is distributed to the expansion drive chamber (33) and the reverse scale drive chamber (32) through the hydraulic diversion valve (17).

4. The carbon dioxide fracturing post-fracturing hole-fracture-wellbore coupled wax removal device according to claim 2, characterized in that, The expansion drive cavity (33) is located between the reverse scale layer (15) and the heating layer (13), and the distance between the expansion drive cavity (33) and the reverse scale layer (15) is less than the distance between the expansion drive cavity (33) and the heating layer (13); the expansion drive cavity (33) is connected to the hydraulic diverter valve (17) through a first pipeline; the first drive flow enters the expansion drive cavity (33) through the first pipeline; The reverse scale driving cavity (32) is located between the reverse scale layer (15) and the heating layer (13), and the distance between the reverse scale driving cavity (32) and the reverse scale layer (15) is greater than the distance between the reverse scale driving cavity (32) and the heating layer (13); the reverse scale driving cavity (32) is connected to the hydraulic diverter valve (17) through a second pipeline; the second driving flow enters the reverse scale driving cavity (32) through the second pipeline.

5. The carbon dioxide fracturing post-fracturing hole-fracture-wellbore coupled wax removal device according to claim 4, characterized in that, The reverse scale driving cavity (32) is also provided with a piston (31), which is connected to the micro rotating shaft (14) through an eccentric wheel (29).

6. The carbon dioxide fracturing post-fracturing hole-fracture-wellbore coupled wax removal device according to claim 5, characterized in that, The magnetic suction valve (11) is installed by an adjustable clamp (23). Its inlet is equipped with an inlet flow meter (22) and an electromagnetically controlled liquid inlet valve (8). It has a multi-stage filtration chamber (9) inside, and is equipped with a timer (7), a depth sensor (21) and a return pipeline (10).

7. The carbon dioxide fracturing post-fracturing hole-fracture-wellbore coupled wax removal device according to claim 1, characterized in that, The pre-cleaning device includes a high-pressure fan-shaped nozzle group (3) and an annular vortex generating chamber (24); the pre-branch is distributed to the high-pressure fan-shaped nozzle group (3) and the annular vortex generating chamber (24); the high-pressure fan-shaped nozzle group (3) includes nozzles (34) evenly distributed on the circumference of the top outer wall and is equipped with an electromagnetic flow regulating valve (26); the inner wall of the annular vortex generating chamber (24) is equipped with an inclined guide vane (25) controlled by a micro-drive mechanism; the micro-drive mechanism is a micro hydraulic motor (5).

8. The carbon dioxide fracturing post-fracturing hole-fracture-wellbore coupled wax removal device according to claim 1, characterized in that, The pre-cleaning device also includes a debris monitoring sensor, a pre-temperature sensor (4), and a pre-pressure sensor (27).

9. The carbon dioxide fracturing post-fracturing hole-fracture-wellbore coupled wax removal device according to claim 1, characterized in that, It also includes a monitoring system; the monitoring system includes a computer located on the ground and a ground remote transmission device (2); it also includes a computer remote receiver (6) installed on the magnetic valve (11); The electromagnetic flow regulating valve (26), the micro hydraulic motor (5), the debris monitoring sensor, the front pressure sensor (27), and the front temperature sensor (4) are all wirelessly connected to the computer remote receiver (6) and transmitted to the computer via the ground remote transmission device (2). The electromagnetic control inlet valve (8), timer (7), inlet flow meter (22), hydraulic diverter valve (17), primary main diverter valve (19), claw pressure sensor (20) and nickel-chromium alloy heating wire are all connected to the computer remote receiver (6) and transmitted to the computer via the ground remote transmission device (2).

10. A post-coupling dewaxing method for borehole-fracture-wellbore after carbon dioxide fracturing, characterized in that, The process of using the carbon dioxide fracturing post-fracturing hole-fracture-wellbore coupled dewaxing device as described in claim 1 is as follows: When the blades are lowered into the wellbore, the reverse scales (30) are in a flat position to reduce the downward resistance and avoid rubbing against the well wall until they are lowered into the wellbore to the predetermined dewaxing position. When the dewaxing position is reached, the magnetic suction valve (11) is opened, and the working fluid flows into the magnetic suction valve (11). After passing through the graded diversion valve, it is divided into a 20%-25% pre-branch and a 75%-80% main working branch. The preceding tributary drives the preceding cleaning device to pre-treat the wellbore; 70% of the main working branch flow is diverted to the expansion drive chamber (33) to generate radial expansion force, and 30% is diverted to the reverse scale drive chamber (32) to drive the reverse scale (30) to rotate. During the wax removal operation, the reverse scale (30) unfolds outward, extends into the perforation gap and continuously rotates to scrape off the surface wax. The device is lifted up; the working fluid is recovered through the return line (10) to complete the operation.

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