Pull valve type double fixed valve sand prevention oil well pump

Abstract

The utility model discloses a pull valve type double fixed valve sand prevention oil well pump, including outer pump cylinder, inner pump cylinder structure, double fixed valve structure, plunger and the upstream valve and downstream valve of plunger both ends installation, the upper oil pipe coupling of outer pump cylinder upper end is provided with, and the lower end is fixed suspension joint through the lower oil pipe coupling, and the double fixed valve structure coupling is fixed below the suspension joint, and the inner pump cylinder structure includes inner cylinder and lengthened pump cylinder, is connected through the coupling, and the lower end coupling of lengthened pump cylinder is fixed in the inside of suspension joint, and the middle of plunger is provided with screen cloth, and a plurality of sand holes are seted up on the plunger simultaneously, and the upstream valve and downstream valve are fixed in the both ends of plunger through the coupling, the utility model discloses structure can effectively solve the technical problem that ball valve cannot be sealed because of sand and scale because of sand grain backfall accumulation in plunger leads to pump jamming, greatly prolongs the service life, reduces the well repair frequency, improves single well oil production efficiency.

Description

Technical Field

[0001] This utility model relates to the field of oil and gas field development in petroleum engineering, and in particular to a pull-valve type double fixed valve sand-proof oil pump. Background Technology

[0002] Rod-type pumps play an indispensable role in oilfields, efficiently extracting crude oil from deep reservoirs through sophisticated mechanical structures. They are widely used in oilfields worldwide. According to statistics from foreign energy companies, over 90% of the world's crude oil is extracted using rod-type pumps. Therefore, developing efficient rod-type pumps is crucial for the economical extraction of crude oil in oilfields. Currently, traditional rod-type pumps face challenges in oilfield applications, including sand production causing pump sticking or ball valve failure leading to frequent downhole accidents. This is a major technical problem affecting the crude oil extraction efficiency of deviated wells, horizontal wells, and heavy oil wells. Based on this, this invention develops a novel anti-sand-sticking pump device. This device effectively prevents sand sticking, reduces well workover frequency, and improves the oil production efficiency of single wells. Utility Model Content

[0003] The purpose of this invention is to provide a pull-valve type double fixed valve sand-proof oil pump, which solves the technical problems faced by rod-type oil pumps in oilfield applications, such as pump jamming caused by sand particles falling and accumulating in the plunger, or the inability of the ball valve to set due to sand and scale. This device can effectively prevent sand jamming, reduce the number of well workovers, and improve the oil production efficiency of a single well.

[0004] The technical solution adopted in this utility model is a pull-valve type double fixed valve sand-proof oil pump, including an outer pump barrel, an inner pump barrel structure, a double fixed valve structure, a plunger, and upstream and downstream moving valves installed at both ends of the plunger. An upper oil pipe coupling is provided at the upper end of the outer pump barrel, and a suspension joint is fixed at the lower end of the outer pump barrel through a lower oil pipe coupling. The double fixed valve structure coupling is fixed below the suspension joint. The inner pump barrel structure includes an inner barrel and an extended pump barrel, which are connected by a coupling. The lower end of the extended pump barrel coupling is fixed inside the suspension joint. The upstream and downstream moving valves are fixed at both ends of the plunger through couplings. A screen is fixed inside the plunger, and multiple sand discharge holes are opened on the plunger.

[0005] The features of this utility model also include: Multiple guide and straightening blocks are fixed at the upper end of the inner pump cylinder structure. The inner pump cylinder structure and the outer pump cylinder are fixed and supported by the guide and straightening blocks and the suspension joint to form a sedimentation space.

[0006] The upstream moving valve includes an upstream moving valve seat, a pull valve, and an upstream moving valve cover. It is connected to the plunger via an upstream moving valve connector and is a forced mechanical valve. The pull rod of the pull valve passes through the upper part of the moving valve cover and connects to the sucker rod. The downstream moving valve includes a downstream moving valve seat, a downstream moving valve ball, and a downstream moving valve cover. It is connected to the plunger via a downstream moving valve connector.

[0007] The double fixed valve structure includes an upper fixed valve cover, an upper fixed valve connector, a lower fixed valve cover, and a lower fixed valve connector, which are fixedly connected in sequence; wherein an upper fixed valve seat and an upper fixed valve ball are installed above the upper fixed valve connector, and a lower fixed valve seat and a lower fixed valve ball are installed above the lower fixed valve connector.

[0008] The contact surface between the valve and the valve seat is designed as a curved contact of two chamfered spherical surfaces.

[0009] The sieves are set in an inverted V shape, and there are three sets, with the mesh size decreasing from top to bottom.

[0010] The sand discharge hole has a diameter of 2mm and is located on the upper side of the connection between the screen and the plunger.

[0011] The screen and sand discharge holes are positioned no higher than the lower end of the coupling between the inner cylinder and the extended pump cylinder.

[0012] The beneficial effects of this utility model are: 1. This device is designed with a screen and sand discharge hole on the plunger, which can discharge the sand particles falling back into the pump barrel through the gap between the plunger and the pump barrel. At the same time, a sand settling channel is designed, which forms an annular space through the inner and outer pump barrels to collect the settled sand and scale and other solid particles, avoiding large amounts of sand and scale clogging the pump barrel or plunger, and greatly extending the service life.

[0013] 2. The upstream valve of this device is a forced mechanical valve, which is forcibly closed or opened by the reciprocating motion of a lever. During the upstroke, it avoids the problem of delayed setting of ordinary ball valves in inclined wells; it also avoids the problem of sand, scale and other impurities sticking to the valve ball, which would cause the valve ball to not set properly or fail to return to its original position; during the downstroke, the mechanical valve is forcibly opened, improving gas prevention performance. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of the pull-valve type double fixed valve sand-proof oil pump of this utility model.

[0015] In the diagram: 1-Upper oil pipe coupling; 2-Guide straightening block; 3-Inner cylinder; 4-Extended pump cylinder; 5-Outer pump cylinder; 6-Lower oil pipe coupling; 7-Suspension joint; 8-Upper fixed valve cover; 9-Upper fixed valve joint; 10-Lower fixed valve cover; 11-Lower fixed valve joint; 12-Upstream moving valve cover; 13-Upstream moving valve seat; 14-Pull valve; 15-Upstream moving valve joint; 16-Plunger; 17-Screen; 18-Sand discharge hole; 19-Downstream moving valve cover; 20-Downstream moving valve ball; 21-Downstream moving valve seat; 22-Downstream moving valve joint; 23-Upper fixed valve ball; 24-Upper fixed valve seat; 25-Lower fixed valve ball; 26-Lower fixed valve seat. Detailed Implementation

[0016] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0017] The directions mentioned in this manual are based on the directions shown in the attached diagram and represent only relative positional relationships, not absolute positional relationships.

[0018] like Figure 1 As shown, the type 14 double fixed valve sand-proof oil pump includes an outer pump barrel 5, an inner pump barrel structure, a plunger 16 inside the inner pump barrel structure, upstream and downstream moving valves fixed at both ends of the inner pump barrel, and a double fixed valve fixed at the bottom of the oil pump.

[0019] The outer pump barrel 5 has the same inner and outer diameters as the oil pipe. The upper end of the outer pump barrel 5 is provided with an upper oil pipe coupling 1 for fixing to the oil extraction pipe, and the lower end is fixed together with the suspension joint 7 through a lower oil pipe coupling 6.

[0020] The inner pump cylinder structure includes an inner cylinder 3 and an extended pump cylinder 4, which are connected by a coupling. The inner cylinder 3 has the same length as a standard plunger to match the length of the fitting section of a standard oil pump, thus avoiding increased frictional resistance. The maximum outer diameters of the inner cylinder 3 and the extended pump cylinder 4 are consistent. Multiple guide and centralizing blocks 2 are fixed between the upper end of the inner cylinder 3 and the outer pump cylinder 5, which enhances the deformation resistance of the inner pump cylinder structure, reduces the load on the pump cylinder, and minimizes leakage. At the same time, the gaps between the guide and centralizing blocks 2 can accommodate sand particles, allowing them to enter and settle in the sedimentation space.

[0021] Since the upstream moving valve cover 12 is always outside the pump cylinder, the inner and outer diameters of the valve cover can be enlarged to improve the structural strength of the moving valve cover.

[0022] The pump cylinder of this device is designed with a double-layer pump cylinder with an inner and an outer pump cylinder 5. The space between the inner and outer pump cylinders 5 is used to guide and contain sand particles, and to prevent sand, scale and other impurities from falling back into the gap between the plunger 16 and the pump cylinder and causing pump jamming.

[0023] The length of plunger 16 is greater than the length of the inner pump cylinder structure, ensuring that the valve seat, pull valve 14, and upstream moving valve cover 12 are always outside the inner pump cylinder structure at the bottom dead center. Three sets of inverted conical screens 17 are fixed inside the plunger 16: the lower screen has a mesh size of 25-50, the middle screen has a mesh size of 50-100, and the upper screen has a mesh size of 150-200. Multiple 2mm diameter sand discharge holes 18 are opened on the upper side of the connection between the plunger 16 and the screens 17. Sand particles falling back into the plunger 16 will be discharged from the sand discharge holes 18 along the surface of the screens 17 due to gravity and the descending liquid level. As the pressure increases during the downstroke, they will be squeezed out from the gap between the plunger 16 and the inner cylinder 3 along with a small amount of crude oil. The screens 17 and the sand discharge holes 18 must not be higher than the lower end of the coupling between the inner cylinder 3 and the extended pump cylinder 4 to prevent the sand discharge holes 18 from protruding from the inner cylinder 3 during operation and causing pressure loss.

[0024] The upstream moving valve includes an upstream moving valve seat 13, a pull valve 14, and an upstream moving valve cover 12. It is connected to the plunger 16 via an upstream moving valve connector 15 and is a forced mechanical valve. The pull rod of the pull valve 14 passes through the upper part of the upstream moving valve cover 12 and connects to the sucker rod. The contact surface between the pull valve 14 and the upstream moving valve seat 13 is designed as a curved surface contact of two chamfered spherical surfaces to increase the contact area between the moving valve ball and the valve seat, further reducing leakage. The downstream moving valve includes a downstream moving valve seat 21, a downstream moving valve ball 20, and a downstream moving valve cover 19. It is connected to the plunger 16 via a downstream moving valve connector 22.

[0025] The dual fixed valve structure includes an upper fixed valve cover 8, an upper fixed valve connector 9, a lower fixed valve cover 10, and a lower fixed valve connector 11, which are fixedly connected in sequence. An upper fixed valve seat 24 and an upper fixed valve ball 23 are installed above the upper fixed valve connector 9, and a lower fixed valve seat 26 and a lower fixed valve ball 25 are installed above the lower fixed valve connector 11. The upper and lower fixed valves work together to better ensure the sealing of the pump casing and effectively reduce leakage.

[0026] The embodiments of this utility model are described in detail below.

[0027] During the upstroke, the pull valve 14 is pulled upward by the sucker rod to be in a forced closed state, which drives the plunger 16 to move upward. Under the action of submersion pressure and pump pressure difference, the double fixed valve ball opens and the downstream moving valve ball 20 closes. The inner cylinder 3 and the extended pump cylinder 4 draw in crude oil. Since the sand particles in the crude oil are mostly extremely fine sand of about 20 micrometers, they will not accumulate at the screen under the action of pressure. Some of the sand particles in the plunger are carried out of the pump cylinder or settle in the sand settling space. The remaining sand particles will accumulate at the three sets of screens 17 under the action of gravity. They are discharged from the plunger 16 through the sand discharge hole 18 with a small amount of crude oil and enter the gap between the plunger 16 and the inner pump cylinder.

[0028] During the downstroke, the pull valve 14 is forced open by the sucker rod, causing the plunger 16 to move downwards. Under the submersion pressure and the pressure difference within the pump, the downstream valve ball 20 opens, and the double fixed valve ball closes. Crude oil in the inner cylinder 3 and the extended pump cylinder 4 is drawn into the plunger 16 through the downstream valve ball 20 and moves upwards. The crude oil in the plunger 16 is discharged from the pump cylinder through the pull valve 14. Sand particles are filtered through three sets of screens 17. At the same time, due to the unavoidable precision errors between the plunger 16 and the inner cylinder 3 during production, some sand particles are transported upwards with the crude oil and discharged from the gap between the plunger 16 and the pump cylinder under pressure. The sand and scale discharged from the plunger 16 and the gap between the plunger 16 and the inner pump cylinder are deposited in the sedimentation space under the action of gravity through the gap between the guide block 2 and the plunger 16.

[0029] Example 1 This embodiment features a pull-valve type dual fixed valve sand-proof oil pump, such as... Figure 1As shown, the system includes an outer pump barrel 5, an inner pump barrel structure, a double fixed valve structure, a plunger 16, and upstream and downstream moving valves installed at both ends of the plunger 16. An upper oil pipe coupling 1 is provided at the upper end of the outer pump barrel 5, and a suspension joint 7 is fixed at the lower end of the outer pump barrel 5 through a lower oil pipe coupling 6. The coupling of the double fixed valve structure is fixed below the suspension joint 7. The inner pump barrel structure includes an inner barrel 3 and an extended pump barrel 4, which are connected by couplings. The coupling at the lower end of the extended pump barrel 4 is fixed inside the suspension joint 7. The upstream and downstream moving valves are fixed at both ends of the plunger 16 through couplings. A screen 17 is fixed inside the plunger 16, and multiple sand discharge holes 18 are opened on the plunger 16.

[0030] The inner cylinder length is equal to that of a standard plunger, and the length of the pump fitting section is also the same as that of a standard pump, preventing increased frictional resistance. The inner and outer diameters of the outer pump barrel are the same as those of the oil pipe. The plunger 16 is longer than the inner pump barrel structure, ensuring that the upstream moving valve seat 13, pull valve 14, and upstream moving valve cover 13 are always outside the inner pump barrel structure at bottom dead center. The long plunger and long pump barrel structure ensures that when the plunger 16 is at bottom dead center, the liquid outlet at the top of the plunger is outside the pump barrel, effectively preventing impurities such as sand and scale from entering the pump barrel. It also lengthens the pump's sealing section, reducing leakage and improving pump efficiency.

[0031] Example 2 This embodiment features a pull-valve type dual fixed valve sand-proof oil pump, such as... Figure 1 As shown, the system includes an outer pump barrel 5, an inner pump barrel structure, a double fixed valve structure, a plunger 16, and upstream and downstream moving valves installed at both ends of the plunger 16. An upper oil pipe coupling 1 is provided at the upper end of the outer pump barrel 5, and a suspension joint 7 is fixed at the lower end of the outer pump barrel 5 through a lower oil pipe coupling 6. The coupling of the double fixed valve structure is fixed below the suspension joint 7. The inner pump barrel structure includes an inner barrel 3 and an extended pump barrel 4, which are connected by couplings. The coupling at the lower end of the extended pump barrel 4 is fixed inside the suspension joint 7. The upstream and downstream moving valves are fixed at both ends of the plunger 16 through couplings. A screen 17 is fixed inside the plunger 16, and multiple sand discharge holes 18 are opened on the plunger 16. The inner pump cylinder structure has multiple guide and straightening blocks 2 fixed at its upper end. The inner pump cylinder structure and the outer pump cylinder 5 are fixedly supported by the guide and straightening blocks 2 and the suspension joint 7 to form a sand settling space. The sand settling space is used to guide and contain impurities: sand, scale and other impurities will fall back under the action of gravity and accumulate in the sand settling space along the gaps between the guide and straightening blocks, avoiding falling back into the gap between the plunger and the pump cylinder and causing pump jamming.

[0032] Example 3 This embodiment features a pull-valve type dual fixed valve sand-proof oil pump, such as... Figure 1As shown, the system includes an outer pump barrel 5, an inner pump barrel structure, a double fixed valve structure, a plunger 16, and upstream and downstream moving valves installed at both ends of the plunger 16. An upper oil pipe coupling 1 is provided at the upper end of the outer pump barrel 5, and a suspension joint 7 is fixed at the lower end of the outer pump barrel 5 through a lower oil pipe coupling 6. The coupling of the double fixed valve structure is fixed below the suspension joint 7. The inner pump barrel structure includes an inner barrel 3 and an extended pump barrel 4, which are connected by couplings. The coupling at the lower end of the extended pump barrel 4 is fixed inside the suspension joint 7. The upstream and downstream moving valves are fixed at both ends of the plunger 16 through couplings. A screen 17 is fixed inside the plunger 16, and multiple sand discharge holes 18 are opened on the plunger 16. The upstream moving valve includes an upstream moving valve seat 13, a pull valve 14, and an upstream moving valve cover 12. The upstream moving valve is clamped to the plunger 16 via an upstream moving valve connector 15. The upstream moving valve cover 12 is clamped to the upstream moving valve connector 15, and the upstream moving valve seat 13 is clamped inside the upstream moving valve cover 12. The pull valve 14 is connected to the sucker rod by passing through the upper part of the upstream moving valve cover 12 via a pull rod. The downstream moving valve includes a downstream moving valve seat 21, a downstream moving valve ball 20, and a downstream moving valve cover 19. The downstream moving valve is clamped to the plunger 16 via a downstream moving valve connector 22. The downstream moving valve cover 19 is clamped to the downstream moving valve connector 22, and the downstream moving valve seat 21 is clamped inside the downstream moving valve cover 19 and a downstream moving valve ball 20 is provided therein.

[0033] The upstream moving valve is a forced mechanical valve, which is forcibly closed or opened by the reciprocating motion of a lever. During the upstroke, it avoids the problem of delayed setting of ordinary ball valves in inclined wells; it also prevents impurities such as sand and scale from adhering to the valve ball, causing problems such as incomplete setting or failure to return to the original position. During the downstroke, the mechanical valve is forcibly opened, improving gas prevention performance. The contact surface between the pull valve 14 and the upstream moving valve seat 13 is designed as a spherical surface. This increases the contact area between the moving valve ball and the valve seat, further reducing leakage.

[0034] Example 4 This embodiment of a pull-valve type double fixed valve sand-proof oil pump includes an outer pump barrel 5, an inner pump barrel structure, a double fixed valve structure, a plunger 16, and upstream and downstream moving valves installed at both ends of the plunger 16. An upper oil pipe coupling 1 is provided at the upper end of the outer pump barrel 5, and a suspension joint 7 is fixed at the lower end of the outer pump barrel 5 through a lower oil pipe coupling 6. The coupling of the double fixed valve structure is fixed below the suspension joint 7. The inner pump barrel structure includes an inner barrel 3 and an extended pump barrel 4, which are connected by a coupling. The lower end of the extended pump barrel 4 is fixed to the inner side of the suspension joint 7. The upstream and downstream moving valves are fixed at both ends of the plunger 16 through couplings. A screen 17 is fixed inside the plunger 16, and multiple sand discharge holes 18 are opened on the plunger 16.

[0035] The dual-fixed valve structure includes an upper fixed valve cover 8, an upper fixed valve connector 9, a lower fixed valve cover 10, and a lower fixed valve connector 11, which are sequentially fixedly connected by couplings. An upper fixed valve seat 24 and an upper fixed valve ball 23 are installed above the upper fixed valve connector 9, while a lower fixed valve seat 26 and a lower fixed valve ball 25 are installed above the lower fixed valve connector 11. The dual-fixed valve structure works in tandem to better ensure the sealing of the pump casing and effectively reduce leakage.

[0036] Example 5 This embodiment features a pull-valve type dual fixed valve sand-proof oil pump, such as... Figure 1 As shown, the system includes an outer pump barrel 5, an inner pump barrel structure, a double fixed valve structure, a plunger 16, and upstream and downstream moving valves installed at both ends of the plunger 16. An upper oil pipe coupling 1 is provided at the upper end of the outer pump barrel 5, and a suspension joint 7 is fixed at the lower end of the outer pump barrel 5 through a lower oil pipe coupling 6. The coupling of the double fixed valve structure is fixed below the suspension joint 7. The inner pump barrel structure includes an inner barrel 3 and an extended pump barrel 4, which are connected by couplings. The coupling at the lower end of the extended pump barrel 4 is fixed inside the suspension joint 7. The upstream and downstream moving valves are fixed at both ends of the plunger 16 through couplings. A screen 17 is fixed inside the plunger 16, and multiple sand discharge holes 18 are opened on the plunger 16.

[0037] The screen 17 is shaped like an inverted cone and consists of three sets, with the mesh size decreasing from top to bottom. The sand discharge hole 18 has a diameter of 2mm and is located on the upper side of the connection between the screen 17 and the plunger 16.

[0038] Since the sand particles in the crude oil are mostly extremely fine sand of about 20 micrometers, they will not accumulate at the screen under pressure. Some sand particles are carried out of the pump barrel with the crude oil during the oil extraction process, while the remaining sand particles will accumulate at the three sets of screens 17 under gravity. They will be discharged from the plunger 16 through the sand discharge hole 18 along with a small amount of crude oil and enter the gap between the plunger 16 and the inner pump barrel. Due to the unavoidable precision error between the plunger 16 and the inner barrel 3 during production, some sand particles will be transported upward with the crude oil and discharged from the gap between the plunger 16 and the pump barrel under pressure. The sand and scale discharged from the plunger 16 and the gap between the plunger 16 and the inner pump barrel will be deposited in the sand settling space under gravity through the gap between the guide block 2 and the plunger 16.

[0039] Example 6 This embodiment features a pull-valve type dual fixed valve sand-proof oil pump, such as... Figure 1As shown, the system includes an outer pump barrel 5, an inner pump barrel structure, a double fixed valve structure, a plunger 16, and upstream and downstream moving valves installed at both ends of the plunger 16. An upper oil pipe coupling 1 is provided at the upper end of the outer pump barrel 5, and a suspension joint 7 is fixed at the lower end of the outer pump barrel 5 through a lower oil pipe coupling 6. The coupling of the double fixed valve structure is fixed below the suspension joint 7. The inner pump barrel structure includes an inner barrel 3 and an extended pump barrel 4, which are connected by couplings. The coupling at the lower end of the extended pump barrel 4 is fixed inside the suspension joint 7. The upstream and downstream moving valves are fixed at both ends of the plunger 16 through couplings. A screen 17 is fixed inside the plunger 16, and multiple sand discharge holes 18 are opened on the plunger 16.

[0040] The screen 17 and the sand discharge hole 18 are both located below the coupling between the inner cylinder 3 and the extended pump cylinder 4. The inner cylinder 3 is the same length as the ordinary plunger to match the length of the ordinary oil pump section. Therefore, during operation, the sand discharge hole 18 is ensured to be blocked and closed by the inner cylinder at the top dead center, preventing the sand discharge hole 18 from extending out of the inner cylinder 3 and causing pressure relief.

Claims

1. A pull-valve type double fixed valve sand-proof oil pump, comprising an outer pump barrel (5), an inner pump barrel structure, a double fixed valve structure, a plunger (16), and an upstream moving valve and a downstream moving valve installed at both ends of the plunger (16), characterized in that, The upper end of the outer pump cylinder (5) is provided with an upper oil pipe coupling (1), and the lower end of the outer pump cylinder (5) is fixed to the suspension joint (7) through the lower oil pipe coupling (6). The double fixed valve structure coupling is fixed below the suspension joint (7). The inner pump cylinder structure includes an inner cylinder (3) and an extended pump cylinder (4), which are connected by couplings. The lower end of the extended pump cylinder (4) is fixed to the inner side of the suspension joint (7). The upstream and downstream moving valves are fixed to both ends of the plunger (16) through couplings. A screen (17) is fixed inside the plunger (16), and multiple sand discharge holes (18) are opened on the plunger (16).

2. The pull-valve type double fixed valve sand-proof oil pump according to claim 1, characterized in that, Multiple guide and straightening blocks (2) are fixed at the upper end of the inner pump cylinder structure. The inner pump cylinder structure and the outer pump cylinder (5) are fixedly supported by the guide and straightening blocks (2) and the suspension joint (7) to form a sand settling space.

3. The pull-valve type double fixed valve sand-proof oil pump according to claim 1, characterized in that, The upstream moving valve includes an upstream moving valve seat (13), a pull valve (14), and an upstream moving valve cover (12). The upstream moving valve is clamped to the plunger (16) via an upstream moving valve connector (15). The upstream moving valve cover (12) is clamped to the upstream moving valve connector (15), and the upstream moving valve seat (13) is clamped to the inside of the upstream moving valve cover (12). The pull valve (14) is connected to the sucker rod by passing through the upper part of the upstream moving valve cover (12) via a pull rod. The downstream moving valve includes a downstream moving valve seat (21), a downstream moving valve ball (20), and a downstream moving valve cover (19). The downstream moving valve is clamped to the plunger (16) via a downstream moving valve connector (22). The downstream moving valve cover (19) is clamped to the downstream moving valve connector (22), and the downstream moving valve seat (21) is clamped to the inside of the downstream moving valve cover (19) and a downstream moving valve ball (20) is provided.

4. The pull-valve type double fixed valve sand-proof oil pump according to claim 3, characterized in that, The contact surface between the pull valve (14) and the upstream moving valve seat (13) is designed to be spherical.

5. The pull-valve type double fixed valve sand-proof oil pump according to claim 1, characterized in that, The dual fixed valve structure includes an upper fixed valve cover (8), an upper fixed valve connector (9), a lower fixed valve cover (10), and a lower fixed valve connector (11), which are connected in sequence by couplings; wherein an upper fixed valve seat (24) is installed above the upper fixed valve connector (9) and an upper fixed valve ball (23) is provided, and a lower fixed valve seat (26) is installed above the lower fixed valve connector (11) and a lower fixed valve ball (25) is provided.

6. The pull-valve type double fixed valve sand-proof oil pump according to claim 1, characterized in that, The sieve (17) is shaped like an inverted cone and consists of three sets, with the mesh size decreasing sequentially from top to bottom.

7. The pull-valve type double fixed valve sand-proof oil pump according to claim 1, characterized in that, The sand discharge hole (18) has a diameter of 2 mm and is located on the upper side of the connection between the screen (17) and the plunger (16).

8. The pull-valve type double fixed valve sand-proof oil pump according to claim 1, characterized in that, The screen (17) and the sand discharge hole (18) are both located below the joint between the inner cylinder (3) and the extended pump cylinder (4).

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