Axial progressive sand removal device for oil and water well bore

Abstract

The application discloses a shaft-in type sand removing device for oil-water well wellbore, which comprises an outer cylinder, a sealing seat, a sliding valve central pipe, a sand disturbing central pipe and a sand disturbing device which are sequentially connected from top to bottom; an inner pipe coupling, an inner pipe short connection, an inner pipe, a liquid separation assembly and a sealing insertion pipe are sequentially connected from top to bottom and are inserted into the outer cylinder; a valve sleeve is sleeved on the outer side of the sliding valve central pipe and the sand disturbing central pipe; a sheath is sleeved on the lower part of the sand disturbing central pipe; a well fluid switch is arranged on the upper part of the sand disturbing device; the switch is opened and closed by lifting and lowering the pipe column; the well fluid switch can freely control the time when the sand carried by the cylinder liquid enters the pipe column, sand deposition and blockage of the central pipe during single pipe connection are avoided, mechanical sand disturbing can be realized in the straight well and horizontal well of the oil-water well, hydraulic sand disturbing and jet pump auxiliary double-pipe continuous sand removing are replaced by water power sand carrying, the sand disturbing mode, sand carrying mode and sand path are changed, and mechanical sand disturbing and jet pump sand removing are integrated.

Description

Technical Field

[0001] This invention relates to the field of sand removal technology for vertical and horizontal wellbores in oil and water wells, and in particular to a shaft-mounted sand removal device for oil and water wells used to shorten operation time and prevent sand from getting stuck and sand flushing fluid from contaminating the oil layer during sand flushing operations in oilfields. Background Technology

[0002] As oilfield development continues, reservoir pressures are reaching new lows, and wellbore conditions are becoming increasingly complex, including vertical wells, horizontal wells, sidetracked wells, and some with deformed casing. Existing hydraulic sand flushing techniques are no longer sufficient to fully address the sand removal needs of oil and water wells.

[0003] The existing technology has the following main problems: 1. In vertical wells and some sidetracked wells, ordinary pen-tip sand flushing causes a large amount of formation sand carried back to the oil layer by the flushing fluid; 2. In horizontal wells, not only is there a problem of a large amount of formation sand carried back to the oil layer by the flushing fluid, but also the formation sand is swept away along the wellbore towards the tip due to the axial impact direction of the lost flushing fluid. The disturbed sand will quickly be re-deposited in the horizontal section and is not easily carried out. If the drilling speed is fast, the tubing string is easily stuck; 3. The loss of flushing fluid causes damage to the formation; 4. To achieve negative pressure sand flushing, packers need to be used, which increases costs by adding well cleaning and tubing scraping procedures and reduces the application scope of the sand flushing process; 5. For oil wells with relatively low formation pressure, the existing negative pressure sand flushing process has more stringent parameter optimization requirements and higher flushing pressure requirements. The performance requirements of the self-sealing wellhead and the cup packer have reached the limit of the process, and it is no longer possible to achieve negative pressure to prevent leakage.

[0004] In recent years, research on sand flushing technology has been quite extensive, with techniques such as rotating jet sand flushing, rotating jet sand flushing with mechanical sand disturbance, and negative pressure sand flushing being successively applied. While these methods have indeed shown better sand flushing effects than ordinary sand flushing, they haven't fundamentally solved the bottleneck problems in oil and water well sand flushing. Firstly, the main impact direction of the horizontal well sand flushing fluid has not been improved, and the problem of secondary sand deposition and tubing jamming at the intersection of the horizontal and vertical sections remains unresolved. Secondly, the problem of sand flushing fluid damaging the oil layer remains unsolved in both vertical and horizontal wells. For example, Chinese patent CN106285523A discloses a horizontal well negative pressure sand pump, whose tubing structure consists of a horizontal well negative pressure sand pump + a single concentric tubing + a sealing cup + a conversion joint + a tool tubing. This invention still employs hydraulic sand disturbance and uses a wellbore packer, failing to fundamentally solve the problem of sand flushing fluid leakage during the horizontal well sand flushing process. Therefore, in-depth research was conducted to address these issues, leading to this case. Summary of the Invention

[0005] The purpose of this invention is to solve the above-mentioned problems by designing an axial-mounted sand removal device for oil and water wells. The device selects a sand-dispersing scheme according to the well conditions, and solves the problems of sand easily getting stuck in the tubing during the existing sand flushing operation of oil and water wells, at the intersection of the horizontal section, the horizontal section and the vertical section, and the vertical section, as well as the problem of the hydraulic impact sand-dispersing fluid carrying formation sand back to the oil layer.

[0006] The technical solution of the present invention to achieve the above objectives is as follows: A shaft-mounted oil and water well sand removal device, comprising an outer cylinder, a sealing seat, a sliding valve center pipe, a sand-dispersing center pipe, a sand-dispersing device, and a guide shoe connected sequentially from top to bottom. The outer cylinder is fitted with an inner pipe coupling, an inner pipe short connector, an inner pipe, a liquid distribution assembly, and a sealing insert, connected sequentially from top to bottom. A valve sleeve is fitted on the outer side of the sliding valve center pipe and the sand-dispersing center pipe. A protective sleeve is slidably fitted on the lower part of the sand-dispersing center pipe. The valve sleeve and the protective sleeve are connected by a centralizing plate. A diffuser and a throat are provided in the inner pipe. The liquid distribution assembly is provided with a nozzle holder, an inlet valve ball, and an inlet valve seat, arranged sequentially from top to bottom. A nozzle and a top pipe are embedded in the nozzle holder. The nozzle and the nozzle holder are axially fixed by the top pipe, which is inserted into the liquid distribution assembly.

[0007] The above-mentioned liquid distribution assembly has a central axial hole at its center and the lower part of the central axial hole is closed. Several axial through holes parallel to the central axial hole and spaced apart from each other are provided on the outside of the central axial hole as liquid inlet channels. The liquid distribution assembly has radial through holes connected to the central axial hole as power fluid flow channels. The liquid inlet channels and power fluid flow channels are not connected to each other.

[0008] Both ends of the aforementioned slide valve center tube are provided with male threads, and the lower end is connected to the sand-disturbing center tube. The middle of the slide valve center tube is a reduced diameter section and a smooth sealing section is provided on the outside. The smooth sealing section has an inlet hole A.

[0009] The upper end of the aforementioned sand-dispersing central tube has an internal thread, and a certain angle chamfer is designed at the top. The chamfered bevel surface is smooth and is used as a valve ball. The outer surface of the middle section of the sand-dispersing central tube is designed with a slide. The lower part of the sand-dispersing central tube is fitted with a sand-dispersing device, and the lower end is connected to a guide shoe.

[0010] The valve sleeve has three sections in its inner diameter, which gradually increases from top to bottom. The first section has the smallest inner diameter and a smooth surface with a sealing groove. The second section forms an inlet ring with the central tube of the slide valve and has an inlet hole B. The third section has a chamfer at the connection with the second section, which is the same as the chamfer at the top of the outer end of the sand-disturbing central tube, serving as a valve seat for mutual sealing. The side wall of the third section has an internal threaded radial hole, and the lower top end of the third section has a slot.

[0011] The upper inner hole of the sheath is provided with a slot and the side wall is provided with an internal threaded radial hole. One end of the straightening plate is inserted into the valve sleeve slot and the other end is inserted into the sheath slot. They are fixed by the upper straightening plate fixing nail and the lower straightening plate fixing nail respectively. The straightening plate drives the sheath to slide axially on the slide.

[0012] The aforementioned sand agitator consists of an upper fixing sleeve, an upper fixing nail, a first sand agitator wire, a fixing ring, a second sand agitator wire, a lower fixing nail, and a lower fixing sleeve. The upper fixing sleeve, the fixing ring, and the lower fixing sleeve are sequentially fitted onto the sand agitator central tube. The first sand agitator wire and the second sand agitator wire are respectively inserted into the gap between the fixing ring and the sand agitator central tube. The upper fixing sleeve and the lower fixing sleeve are respectively locked and fixed by the upper fixing nail and the lower fixing nail.

[0013] The first and second sand-dispersing wires are both perpendicular to the central sand-dispersing tube and are on the same horizontal plane. The first and second sand-dispersing wires are double-bent in shape on the horizontal plane.

[0014] Shallow grooves are provided on both ends of the aforementioned fixing ring, and the number, width, and depth of the shallow grooves are the same as the number and diameter of the first and second sand-dispersing wires.

[0015] The outer cylinder has threaded ends at both the top and bottom. The upper end is connected to an oil pipe, and the lower end is connected to a sealing seat. The lower end of the sealing seat is provided with a female thread to connect to the central tube of the slide valve.

[0016] The lower part of the aforementioned sand-disturbing center pipe is connected to a vertical well sand-disturbing device. The vertical well sand-disturbing device has an overall structure of an upper cylinder and a lower cone. The outer wall of the internal thread section is a cylinder, and the lower part of the internal thread section is a cone with a certain taper, which is thicker at the top and thinner at the bottom. It is divided into several units, and each unit independently forms a cone, which is thicker at the top and thinner at the bottom. The upper surface of each cone is raised to form a certain acute angle with the axis and also forms a certain acute angle with the outer cone surface, and is rounded. The bottom is an acute angle or cone angle with a certain angle with the axis.

[0017] The shaft-mounted sand removal device for oil and water wells manufactured using the technical solution of this invention has beneficial effects. The purpose of this invention is to address the production problems mentioned in the background art by providing a shaft-mounted sand removal device for oil and water wells. With this device and other wellhead accessories, mechanical sand removal can replace hydraulic sand removal, and jet pump-assisted dual-pipe continuous sand removal can replace hydraulic sand carrying. By changing the sand removal method, sand carrying method, and sand path, many problems of traditional hydraulic sand flushing are solved, realizing the integration of mechanical sand removal and jet pump sand removal, effectively improving the oilfield development effect.

[0018] Meanwhile, to prevent sand from clogging the central pipe when connecting a single pipe, a well fluid switch is installed on the upper part of the sand stirrer. The switch can be turned on and off by raising and lowering the tubing string. The well fluid switch can freely control the timing when the well fluid carries sand into the tubing string, thus avoiding sand deposition and clogging of the central pipe when connecting a single pipe. The advantages are as follows: First, by mechanically disturbing the sand, the flushing fluid does not come into contact with the oil layer, thus avoiding contamination of the oil layer. Compared with vertical wells, horizontal wells are more prone to sand leakage, resulting in more serious contamination of the oil layer. Therefore, this invention effectively avoids sand leakage to the oil layer. Second, it avoids secondary deposition of formation sand that can cause tubing blockage. Due to the special structure of vertical and horizontal wells in oil and water wells, in traditional hydraulic sand flushing operations, the formation sand disturbed by hydraulics will redeposit in a very short time, generally not exceeding 0.5 seconds. Therefore, sand can easily block the tubing, causing major well workovers. Third, it has high sand flushing efficiency. Due to the small volume of the central tubing, the required circulation time is shortened, improving efficiency. At the same time, there is no problem of sand flushing fluid leakage, shortening the sand flushing circulation time. Fourth, it has low requirements for the wellbore, expanding its application range. Fifth, it reduces supporting procedures, lowers costs, and improves operational efficiency.

[0019] This invention effectively avoids the adverse consequences of conventional sand flushing. Conventional sand flushing requires re-establishing circulation after each single connection, necessitating several times the circulation volume each time. This leads to increased leakage of flushing fluid and severe contamination of the oil reservoir. This invention addresses the unavoidable technical shortcomings of continuous sand flushing. Formation sand needs a certain flow velocity to be carried to the surface; if the velocity is too low, prolonged circulation is required, extending operation time and reducing efficiency. Simultaneously, the increased leakage of flushed sand into the formation due to the extended operation time also causes serious damage to the oil reservoir. This invention, by using small-diameter concentric double pipes, intentionally reduces the flow area of ​​the return fluid, increasing its flow velocity by 3-6 times, significantly improving sand-carrying capacity, shortening operation time, and reducing the harm to the oil reservoir caused by sand flushing. Furthermore, continuous circulation completely avoids the formation sand back-settling caused by stopping circulation when connecting single connections, playing a crucial role in improving sand flushing efficiency and protecting the oil reservoir. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the main structure of the sand removal device described in Embodiment 1 of the present invention.

[0021] Figure 2 This is a schematic diagram of the upper part of the sand removal device described in Embodiment 1 of the present invention.

[0022] Figure 3 This is a schematic diagram of the lower half of the sand removal device described in Embodiment 1 of the present invention.

[0023] Figure 4 This is a cross-sectional view of the sand removal device at position AA according to Embodiment 1 of the present invention.

[0024] Figure 5 This is a cross-sectional view of the sand removal device at position BB according to Embodiment 1 of the present invention.

[0025] Figure 6 This is a schematic diagram of the structure of the sand removal device with the vertical well sand disturber described in Embodiment 2 of the present invention.

[0026] Figure 7 For the present invention Figure 6 A partially enlarged structural diagram.

[0027] In the diagram: 1-Outer cylinder; 2-Inner tube coupling; 3-Inner tube short connector; 4-Inner tube; 5-Diffuser tube; 6-Throat tube; 7-Nozzle; 8-Nozzle holder; 9-Top tube; 10-Distribution assembly; 10-1-Inlet flow channel; 10-2-Power fluid flow channel; 10-3-Inlet valve ball; 10-4-Inlet valve seat; 11-Sealing insert; 12-Sealing seat; 13-Slide valve center tube; 13-1-Inlet hole A; 14-Valve sleeve; 14- 1-Inlet ring; 14-2-Inlet hole B; 15-Fixing pin; 16-Friction stabilizer; 17-Sand-dispersing center tube; 17-1 Slide; 18-Sheath; 19-Fixing pin; 20-Sand-disperser; 20-1-Fixing sleeve; 20-2-Fixing pin; 20-3-Sand-dispersing wire; 20-4-Fixing ring; 20-5-Sand-dispersing wire; 20-6-Fixing pin; 20-7-Fixing sleeve; 21-Guiding shoe; 22-Vertical well sand-disperser. Detailed Implementation

[0028] The present invention will now be described in detail with reference to the accompanying drawings, such as... Figure 1-5 As shown, the components in this case can be connected sequentially by those skilled in the art. The specific connection and operation sequence should refer to the working principle described below. The detailed connection methods are well-known technologies in the art. The working principle and process are mainly described below.

[0029] Example 1: Application of this device in horizontal wells, as described in the attached instructions. Figure 1-5As can be seen, the sand removal device of this scheme consists of an outer cylinder 1, a sealing seat 12, a slide valve center tube 13, a sand-dispersing center tube 17, a sand-dispersing device 20, and a guide shoe 21 connected from top to bottom. The outer cylinder 1 is fitted with an inner tube coupling 2, an inner tube short connector 3, an inner tube 4, a liquid distribution assembly 10, and a sealing insert 11, connected from top to bottom. A valve sleeve 14 is fitted around the outside of the slide valve center tube 13 and the sand-dispersing center tube 17. A protective sleeve 18 is slidably fitted around the lower part of the sand-dispersing center tube 17. The valve sleeve 14 and the protective sleeve 18 are connected by a centralizing plate 16. The inner tube 4 contains a diffuser tube 5 and a throat tube 6. The liquid distribution assembly 10 contains a nozzle holder 8, an inlet valve ball 10-3, and an inlet valve seat 10-4, arranged from top to bottom. The nozzle holder 8 contains a nozzle 7. The jacking pipe 9, nozzle 7, and nozzle holder 8 are axially fixed by the jacking pipe 9. The jacking pipe 9 is inserted into the liquid distribution assembly 10. The liquid distribution assembly 10 has a central axial hole with the lower part closed. Several axial through holes parallel to the central axial hole and spaced apart from each other are provided on the outside of the central axial hole as liquid inlet channels 10-1. The liquid distribution assembly 10 has radial through holes connected to the central axial hole as power fluid flow channels 10-2. The liquid inlet channels 10-1 and power fluid flow channels 10-2 are not connected to each other. Both ends of the above-mentioned slide valve center pipe 13 are provided with male threads, and the lower end is connected to the sand turbulence center pipe 17. The middle of the slide valve center pipe 13 is a reduced diameter section and the outer side is provided with a smooth sealing section. The smooth sealing section has a liquid inlet hole A13-1. The upper end of the aforementioned sand-dispersing center tube 17 has an internal thread, and a certain angle chamfer is designed at the top end. The chamfered bevel surface is smooth and is used as a valve ball. The outer surface of the middle section of the sand-dispersing center tube 17 is designed with a slide 17-1. The sand-dispersing center tube 17 is fitted with a sand-dispersing device 20 at the lower part, and the lower end is connected to the guide shoe 21. Both the upper and lower ends of the outer cylinder 1 are threaded. The upper end is connected to the oil pipe, and the lower end is connected to the sealing seat 12. The lower end of the sealing seat 12 is provided with a female thread to connect with the slide valve center tube 13. The valve sleeve 14 has an inner diameter divided into three sections, with the inner diameter gradually increasing from top to bottom. The first section has the smallest inner diameter and a smooth surface with a sealing groove. The second section forms an inlet ring 14-1 with the slide valve center tube 13 and has an inlet hole B14-2. The third section has a chamfer at the connection with the second section, which is the same as the chamfer at the outer top end of the sand-disturbing center tube 17, serving as a valve seat for mutual sealing. The side wall of the third section has an internal thread radial hole, and the lower top end of the third section has a slot. The upper end of the sheath 18 has a slot and the side wall has an internal threaded radial hole. One end of the straightening plate 16 is inserted into the slot of the valve sleeve 14 and the other end is inserted into the slot of the sheath 18. They are fixed by the upper straightening plate fixing nail 15 and the lower straightening plate fixing nail 19 respectively. The straightening plate 16 can drive the sheath 18 to slide axially on the slide 17-1.

[0030] The aforementioned sand agitator 20 comprises an upper fixing sleeve 20-1, an upper fixing pin 20-2, a first sand agitator wire 20-3, a fixing ring 20-4, a second sand agitator wire 20-5, a lower fixing pin 20-6, and a lower fixing sleeve 20-7. The upper fixing sleeve 20-1, the fixing ring 20-4, and the lower fixing sleeve 20-7 are sequentially fitted onto the sand agitator center tube 17. The first sand agitator wire 20-3 and the second sand agitator wire 20-5 are respectively inserted into the gap between the fixing ring 20-4 and the sand agitator center tube 17, utilizing the upper fixing pin 20-6 to agitate the sand agitator wire 20-7. The fixing pins 20-2 and 20-6 lock and fix the upper fixing sleeve 20-1 and the lower fixing sleeve 20-7. The first sand-dispersing wire 20-3 and the second sand-dispersing wire 20-5 are both perpendicular to the sand-dispersing center tube 17 and are both on the same horizontal plane. The first sand-dispersing wire 20-3 and the second sand-dispersing wire 20-5 are double-bent in the horizontal plane. Shallow grooves are provided on both ends of the fixing ring 20-4. The number, width, and depth of the shallow grooves are the same as the number and diameter of the first sand-dispersing wire 20-3 and the second sand-dispersing wire 20-5. The working principle and operation process are as follows: First, the outer cylinder 1, sealing seat 12, sliding valve center pipe 13, sand-dispersing center pipe 17, sand-dispersing device 20, and guide shoe 21 are lowered from top to bottom into the horizontal section of the well using large-diameter tubing. Then, the inner pipe coupling 2, inner pipe short connector 3, inner pipe 4, fluid distribution assembly 10, sealing insert 11, and all internal accessories are lowered into the well using small-diameter tubing. The sealing insert 11 sits inside the sealing seat 12 and is sealed by a sealing ring. The power fluid and return fluid lines are connected through wellhead accessories. After the system pressure test is passed, a small-volume, low-pressure circulation begins. After circulation is established, the power fluid displacement is further increased to increase the power fluid pressure, initiating high-pressure circulation. Simultaneously, the double-layer tubing is repeatedly raised and lowered synchronously. In the wellbore, the sand is agitated by the sand stirrer 20 and suspended in the wellbore fluid. Further high-pressure power fluid enters from the double-pipe annulus, passes through the power fluid flow channel 10-2 and the top pipe 9, and enters the nozzle. After passing through the nozzle, most of the pressure energy of the power fluid is converted into kinetic energy, forming a low-pressure zone near the nozzle. The agitated and suspended formation sand in the horizontal section, along with the well fluid, passes through the inlet hole B14-2, the inlet annulus 14-1, and the inlet hole A13-1, continuously through the sealed insertion pipe 11, the inlet valve seat 10-4, the inlet flow channel 10-1, and the nozzle holder 8 into the low-pressure zone. It mixes with the power fluid and undergoes energy conversion before entering the throat pipe 6. It then passes through the diffuser pipe 5 to gradually reduce kinetic energy and increase pressure energy, and is finally lifted to the surface.

[0031] When the power fluid pressure is low and insufficient to lift the well fluid, the inlet valve ball 10-3 sits on the inlet valve seat 10-4, preventing the power fluid from entering the well.

[0032] When replacing a single tube, the tubing string is lifted a certain distance. The sliding sleeve 14 remains stationary or slides slowly under the friction between the centralizing plate 16 and the casing. Its upward sliding speed is less than the lifting speed of the double tubes. Finally, the sliding sleeve 14 and the sand-disturbing center tube 17 are sealed by the chamfer and further circulated. The well fluid cannot enter the inner tube. After sufficient circulation time, it is confirmed that there is no formation sand in the returned fluid. Then, the single tube is connected to carry out the next step of sand flushing.

[0033] To prevent sand from clogging the central pipe when connecting a single pipe, a well fluid switch is installed on the upper part of the sand stirrer. The switch can be turned on and off by raising and lowering the tubing string. The well fluid switch can freely control the timing when the well fluid carries sand into the tubing string, thus avoiding sand deposition and clogging of the central pipe when connecting a single pipe.

[0034] Example 2: Application of this device in vertical wells. Based on the structure of the device in Example 1, a segmented stepped vertical well sand deflector 22 is connected to the lower part of the sand deflector center pipe 17. The upper part of the vertical well sand deflector 22 is a tubing female thread, which facilitates connection with the central sand deflector center pipe 17 of the fluid inlet valve. The vertical well sand deflector 22 is a cylindrical upper and conical lower structure, and is a solid body including but not limited to. The outer wall of the internal thread section is cylindrical, and the lower part is a uniformly tapered cone with a certain degree of taper, thicker at the top and thinner at the bottom, and is divided into several units. Each unit independently forms a cone, thicker at the top and thinner at the bottom. The upper surface of each cone is raised to form a certain acute angle with the axis, that is, α is less than 90° in the figure, and also forms a certain acute angle with the outer cone surface, and is rounded. The bottom is an acute angle or cone angle with a certain angle with the axis. See details. Figure 6 and appendix Figure 7The working principle and operation process are as follows: First, the outer cylinder 1, sealing seat 12, sliding valve center pipe 13, sand-dispersing center pipe 17, and sand-dispersing device 22 are lowered into the vertical well using a large-diameter tubing from top to bottom. Then, the inner pipe coupling 2, inner pipe short connector 3, inner pipe 4, fluid distribution assembly 10, sealing insert 11, and all internal accessories are lowered into the well using a small-diameter tubing. The sealing insert 11 sits inside the sealing seat 12 and is sealed by a sealing ring. The power fluid and return fluid lines are connected through wellhead accessories. After the system pressure test is passed, a small-volume, low-pressure circulation begins. After circulation is established, the power fluid displacement is further increased to increase the power fluid pressure, initiating high-pressure circulation. Simultaneously, the double-layer tubing string is repeatedly raised and lowered synchronously, and sand in the wellbore is dispersed through the sand-dispersing device. The sand 22 is disturbed and suspended in the well fluid. Further high-pressure power fluid enters from the double-pipe annulus, passes through the power fluid flow channel 10-2 and the top pipe 9, and enters the nozzle. After passing through the nozzle, most of the pressure energy of the power fluid is converted into kinetic energy, forming a low-pressure zone near the nozzle. The disturbed and suspended formation sand, along with the well fluid, passes through the inlet hole B14-2, the inlet annulus 14-1, and the inlet hole A13-1, continuously through the sealed insertion pipe 11, the inlet valve seat 10-4, the inlet flow channel 10-1, and the nozzle holder 8 into the low-pressure zone. It mixes with the power fluid and undergoes energy conversion before entering the throat pipe 6. It then passes through the diffuser pipe 5 to gradually reduce kinetic energy and increase pressure energy, and is finally lifted to the surface. The specific operation and principle of replacing the single pipe are the same as in Example 1.

[0035] By mechanically disturbing the sand, the flushing fluid does not come into contact with the oil layer, thus avoiding contamination. Compared to vertical wells, horizontal wells are more prone to sand leakage, resulting in more severe contamination of the oil layer. Therefore, this invention effectively avoids sand leakage and oil layer contamination. It can also prevent secondary deposition of formation sand that can cause tubing blockage. Due to the special structure of horizontal wells, in traditional hydraulic sand flushing operations, the formation sand disturbed by hydraulic forces will redeposit in a very short time, generally not exceeding 0.5 seconds, which can easily cause sand to block the tubing and lead to major well workovers. The flushing efficiency is high. Due to the small volume of the central tube, the required circulation time is shortened, improving efficiency. At the same time, there is no problem of sand leakage, shortening the sand flushing circulation time. It has low requirements for the wellbore, expanding its application range. It reduces supporting procedures, lowers costs, and improves operational efficiency. By using small-diameter concentric double tubes, the flow area of ​​the returned fluid is intentionally reduced, increasing its flow velocity by 3-6 times, significantly improving sand carrying capacity, shortening operation time, and reducing the damage to the oil layer caused by sand flushing operations. At the same time, continuous circulation completely avoids the formation sand back-sinking caused by stopping circulation when connecting single roots, which plays an important role in improving the efficiency of sand flushing operations and protecting oil layers.

[0036] With this device and other wellhead accessories, mechanical sand flushing can replace hydraulic sand flushing in vertical and horizontal wells of oil and water, and jet pump-assisted continuous sand discharge can replace hydraulic sand carrying. By changing the sand flushing method, sand carrying method and sand path, many problems of traditional hydraulic sand flushing can be solved, realizing the integration of mechanical sand flushing and jet pump sand discharge, effectively improving the oilfield development effect.

[0037] Especially considering that over 90% of my country's oilfields are sandstone reservoirs, and with deepening development, reservoir pressure is continuously decreasing, particularly with the expansion of horizontal wells and the increase in sidetracked and casing-deformed wells, existing sand flushing techniques are no longer sufficient to solve the problem of sand removal from oil and water wells. Firstly, the formation sand disturbed by hydraulic pressure will redeposit within a very short time, generally no more than 0.5 seconds, easily causing sand to jam the tubing and leading to major well workovers. Simultaneously, long-term depressurization or inadequate water injection results in low formation pressure in most oil wells, leading to significant working fluid loss during sand flushing operations. Working fluid loss increases production costs due to reduced operational efficiency; secondly, it damages the reservoir, increasing the production cost of repairing the damage; and thirdly, it raises the question of whether the damaged reservoir can function normally, resulting in wasted production capacity. These are unavoidable problems in the later stages of oilfield development, therefore, this invention has broad application prospects.

[0038] The above technical solutions only embody the preferred technical solutions of the present invention. Any modifications that may be made by those skilled in the art to certain parts thereof embody the principles of the present invention and fall within the protection scope of the present invention.

Claims

1. A shaft-mounted sand removal device for oil and water wells, characterized in that, The outer cylinder (1), sealing seat (12), slide valve center tube (13), sand-dispersing center tube (17), and sand-disperser (20) are connected from top to bottom. The outer cylinder (1) is fitted with an inner tube coupling (2), an inner tube short connector (3), an inner tube (4), a liquid distribution assembly (10), and a sealing insert (11), connected from top to bottom. A valve sleeve (14) is fitted around the slide valve center tube (13) and the sand-dispersing center tube (17). A protective sleeve (18) is slidably fitted around the lower part of the sand-dispersing center tube (17). The valve sleeve (14) and the protective sleeve (18) are connected by a straightening plate (16). The inner tube (4) is provided with a diffuser (5) and a throat (6). The liquid distribution assembly (10) is provided with a nozzle holder (8), an inlet valve ball (10-3) and an inlet valve seat (10-4) from top to bottom. The nozzle holder (8) is fitted with a nozzle (7) and a top tube (9). The nozzle (7) and the nozzle holder (8) are axially fixed by the top tube (9). The top tube (9) is inserted into the liquid distribution assembly (10). The liquid distribution assembly (10) has a central axial hole at its center and the lower part of the central axial hole is closed. Several axial through holes parallel to the central axial hole and spaced apart from each other are provided on the outside of the central axial hole as liquid inlet channels (10-1). The liquid distribution assembly (10) has radial through holes connected to the central axial hole as power fluid flow channels (10-2). The liquid inlet channels (10-1) and power fluid flow channels (10-2) are not connected to each other.

2. The shaft-mounted oil and water well sand removal device according to claim 1, characterized in that, Both ends of the slide valve center tube (13) are provided with male threads, and the lower end is connected to the sand-disturbing center tube (17). The middle of the slide valve center tube (13) is a reduced diameter section and the outer side is provided with a smooth sealing section. The smooth sealing section is provided with an inlet hole A (13-1).

3. The shaft-mounted oil / water well sand removal device according to claim 1, characterized in that, The upper end of the sand-dispersing central tube (17) is internally threaded, and a certain angle chamfer is designed at the top end. The chamfered bevel surface is smooth and is used as a valve ball. The outer surface of the middle section of the sand-dispersing central tube (17) is designed with a slide (17-1). The lower part of the sand-dispersing central tube (17) is fitted with a sand-dispersing device (20), and the lower end is connected to a guide shoe (21).

4. A shaft-mounted oil / water well sand removal device according to claim 3, characterized in that, The valve sleeve (14) has three sections in its inner diameter, which gradually increases from top to bottom. The first section has the smallest inner diameter and a smooth surface with a sealing groove. The second section forms an inlet ring (14-1) with the slide valve center tube (13) and has an inlet hole B (14-2). The third section is connected to the second section with a chamfer that is the same as the chamfer on the outer top of the sand-disturbing center tube (17) to serve as a valve seat for mutual sealing. The side wall of the third section has an internal thread radial hole and a slot is provided at the lower top of the third section.

5. A shaft-mounted oil / water well sand removal device according to claim 4, characterized in that, The upper end of the sheath (18) has a slot and the side wall has an internal threaded radial hole. One end of the straightening plate (16) is inserted into the slot of the valve sleeve (14) and the other end is inserted into the slot of the sheath (18). They are fixed by the upper straightening plate fixing nail (15) and the lower straightening plate fixing nail (19) respectively. The straightening plate (16) drives the sheath (18) to slide axially on the slide (17-1).

6. A shaft-mounted oil / water well sand removal device according to claim 1, characterized in that, The lower part of the sand-disturbing center pipe (17) is connected to a vertical well sand-disturbing device (22).

7. According to claim 6, the vertical well sand remover (22) is a cylindrical structure with a conical bottom. The vertical well sand remover (22) is a solid or hollow structure. The upper part of the vertical well sand remover (22) is provided with an internal thread section. The outer wall of the internal thread section is a cylinder. Below the internal thread section, there are cones with a certain taper, which are thicker at the top and thinner at the bottom. The cones are divided into several units, and each unit independently forms a cone, which is thicker at the top and thinner at the bottom. The upper surface of each cone is raised to form a certain acute angle with the axis and also forms a certain acute angle with the outer cone surface. The cone is rounded. The bottom part is an acute angle or cone angle with a certain angle with the axis.

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