Sand setting screw pump and working method

Abstract

The invention provides a sand setting screw pump and a working method, relates to the field of screw pumps, and aims at solving the problems that in the prior art, gravity setting easily induces pump jamming and sand-containing fluid is prone to bridging and blocking. Gravel in pumped fluid is thrown to the inner wall of the outer pipe and moves downwards along the annular sand setting space, the gravel moving downwards along the inner wall of the outer pipe can penetrate through the two-way connector to smoothly settle into the sand setting tail pipe in cooperation with the longitudinal through sand setting channel formed in the two-way connector, the accumulation risk caused by structural interference existing in a flow channel is reduced, and the service life of the flow channel is prolonged. And the sand setting channel and the liquid inlet channel do not interfere with each other, and the cooperative work of active centrifugal separation and longitudinal through discharge is adopted, so that the sand concentration of fluid at the outlet of the stator assembly is reduced, and the situation that gravel settles and falls back into a stator cavity is effectively reduced, so that the probability that the screw pump is stuck is reduced, and abrasion is reduced.

Description

Technical Field

[0001] This invention relates to the field of screw pumps, and more specifically to a sedimentation screw pump and its operating method. Background Technology

[0002] Screw pumps, due to their simple structure and stable lifting, are widely used in high-sand oil wells and coalbed methane drainage and gas production operations. During conventional production, the large amount of sand or coal dust carried in the well fluid can easily damage downhole equipment. Especially during unit shutdowns or intermittent oil production, suspended solid particles in the tubing and the upper part of the pump's lifting fluid will fall back under gravity and deposit at the stator-rotor meshing point or around the pump body, easily forming a dense accumulation layer. This can lead to excessive torque or even pump seizure when the pump is restarted, requiring pump inspection and well workover operations, increasing production costs and reducing extraction efficiency. Therefore, existing technologies typically employ devices such as sand anchors, annular sand barriers, or sand screens, mainly utilizing the principle of natural gravity settling to passively collect the falling sand and gravel, aiming to reduce the risk of sand burial.

[0003] However, in existing sand settling or sand prevention structures, the settled sand and gravel are mostly discharged after the machine is shut down. However, the amount of sand and gravel deposited on the stator is relatively large, and it is still easy for the sand and gravel to enter the stator cavity with the fluid during the sand and gravel discharge process, causing difficulties in starting the pump. In addition, there is structural interference or tortuous path between the liquid inlet and the sand settling channel. For example, in the existing technology, perforated plate filtration or lateral baffle is used. High-concentration sand-containing fluid is prone to bridging and blockage at the diameter change or blind area, resulting in the failure of the sand settling channel and making it difficult to meet the requirements of reducing pump jamming and wear. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by providing a sand-removing screw pump and its operating method, which enables pre-sand removal during the pumping process and guides settled sand and gravel into the sand-removing tailpipe below the inlet channel, thereby reducing the probability of pump jamming and wear.

[0005] The first objective of this invention is to provide a sedimentation screw pump, comprising a rotor, a stator assembly, an outer tube, a double-connector, and a sedimentation tailpipe;

[0006] The outer tube is sleeved outside the stator assembly, and an annular sand settling space is formed between the stator assembly and the inner wall of the outer tube; the lower end of the outer tube is connected to the sand settling tail tube through a double-connector. The rotor is installed inside the stator assembly. The upper part of the rotor has an exposed section extending out of the upper end face of the stator assembly. The exposed section is used to drive the fluid to generate centrifugal force during rotation to throw the sand and gravel towards the inner wall of the outer tube so that it falls into the annular sand settling space. The dual-connector has a longitudinally connected sand settling channel and a fluid inlet channel isolated from the sand settling channel; the annular sand settling space is connected to the sand settling tailpipe via the sand settling channel, and the fluid inlet channel is connected to the external well fluid and the fluid inlet of the stator assembly.

[0007] Furthermore, it also includes a centering block disposed on the upper end of the stator assembly. The centering block maintains the relative position between the stator assembly and the outer tube. The centering block has multiple radially extending guide claws, and an open flow channel is formed between adjacent guide claws to allow gravel to adhere to the inner wall of the outer tube and pass through.

[0008] Furthermore, when the exposed section rotates, it drives the fluid to generate a spiral centrifugal force. The upper end of the guide claw extends above the upper end face of the stator assembly, and the guide claw is provided with a guide surface to guide the rotor into the stator assembly.

[0009] Furthermore, the double-pass connector includes a double-pass housing and a double-pass component. The upper end of the double-pass housing is connected to an outer pipe, the lower end is connected to a sand-collecting pipe, and it is sleeved on the outside of the double-pass component. The liquid inlet channel is opened on the double-pass component, and the side wall of the double-pass housing is provided with a liquid inlet hole communicating with the liquid inlet channel.

[0010] Furthermore, the dual-connector also includes a connector component that connects the liquid inlet channel and the liquid inlet of the stator assembly.

[0011] Furthermore, the sand-collecting channel within the double-through joint is a straight hole that extends along the axial direction of the double-through component.

[0012] Furthermore, the liquid inlet of the stator assembly is formed by a limiter, the upper end of which is connected to the lower end of the stator assembly via a middle clamp, and the lower end of the limiter is connected to a double-through connector.

[0013] Furthermore, the sand-sinking tailpipe is composed of multiple sections of oil pipe connected together, and a blind plug is provided at the bottom of the sand-sinking tailpipe.

[0014] A second objective of this invention is to provide a method for operating a sedimentation screw pump, utilizing the sedimentation screw pump described in the first objective, comprising: The rotor is driven to rotate, and the external well fluid enters through the inlet channel inside the double-through joint, which is isolated from the sand-settling channel, and is transported to the inlet of the stator assembly, where it is transported upward under the drive of the rotor. The exposed section extending from the upper part of the rotor to the upper end face of the stator assembly drives the fluid to rotate, generating centrifugal force and throwing the sand and gravel in the fluid toward the inner wall of the outer tube. The ejected gravel descends along the annular sedimentation space formed between the stator assembly and the inner wall of the outer tube, passes through the longitudinally penetrating sedimentation channel inside the double-connector, and settles into the sedimentation tailpipe for storage.

[0015] Furthermore, the length of the sand-sinking tailpipe is predetermined based on the sand content of the oil well, and different numbers of oil pipes are connected in series to form the sand-sinking tailpipe to match the sand storage requirements of the oil well.

[0016] Compared with the prior art, the advantages and positive effects of this invention are: To address the problems in existing technologies where relying solely on gravity settling during shutdown can easily lead to pump jamming, and the tendency for high-concentration sand-laden fluids to become bridging and blocked due to tortuous flow channels or structural interference, an exposed section is installed above the stator assembly. This section utilizes the centrifugal force generated by rotor rotation to establish an active sorting mechanism, throwing sand and gravel in the pumped fluid towards the inner wall of the outer pipe and allowing it to descend along the annular sand settling space. This achieves pre-sand removal of the fluid. Combined with a longitudinally penetrating sand settling channel within the double-connector, the sand and gravel descending along the inner wall of the outer pipe can smoothly pass through the double-connector and settle into the sand settling tailpipe, reducing the risk of accumulation due to structural interference in the flow channel. Furthermore, the sand settling channel and the inlet channel do not interfere with each other. The synergistic effect of active centrifugal sorting combined with longitudinally penetrating discharge reduces the sand concentration in the fluid at the stator assembly outlet, effectively reducing the amount of sand and gravel settling back into the stator cavity and minimizing secondary accumulation of settled sand and gravel near the inlet. This reduces the probability of screw pump jamming and decreases wear.

[0017] To address the problem of existing perforated plate filters creating dead zones at the edges that cause sand and gravel accumulation and blockage, a centralizing block with multiple guide claws is adopted. The guide claws extend radially, creating a large fan-shaped gap between adjacent guide claws and constructing a radially fully open flow channel. While maintaining the coaxiality of the stator assembly and the outer tube, it reduces the obstruction of the inner wall of the outer tube and adapts to the spiral downward movement trajectory of sand and gravel under centrifugal force. This allows high-concentration sand-containing fluid to pass through the centralizing block area with low resistance, reducing the risk of sand and gravel bridging or accumulating at the constriction of the flow channel and improving the flow efficiency of the sedimentation channel.

[0018] The sedimentation channel is configured as a straight hole running through the axial direction, which allows the gravel to settle directly by gravity, reducing the resistance of the gravel to descend and ensuring the continuity of sedimentation.

[0019] A guide surface is provided on the guide claw to guide the rotor into the stator assembly, ensuring that the rotor can slide smoothly into the stator assembly during installation, thus solving the problem of difficulty in aligning a long rotor with the stator assembly.

[0020] Based on the configuration scheme of pre-connecting different numbers of tubing to form a sand-sinking tailpipe according to the sand content, the sand-sinking space is transformed from a fixed capacity to an adjustable capacity by utilizing the scalability of standard tubing. This can extend the effective service time of the sand-sinking device for oil wells with different geological conditions, effectively reduce the frequency of well workover operations forced due to sand filling, and improve the economic benefits of oil well production.

[0021] The various structures in this invention are not simply pieced together, but rather establish a complete fluid dynamics sand control logic. In the initial position, an exposed rotor throws sand toward the wall. During the flow guidance process, a claw-type straightening block without edge obstruction allows the sand to flow downward along the wall. The sand and gravel are directly discharged to the bottom through a double-through connector to achieve separation from the well fluid. Finally, the sand and gravel are stored in a variable-length tailpipe. These four links are interlocked and together solve the technical defects of low efficiency of passive sand control and easy blockage of dead corners in the flow channel in the existing technology. Attached Figure Description

[0022] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0023] Figure 1 This is a schematic diagram of the structure of a sedimentation screw pump in one or more embodiments of the present invention.

[0024] Figure 2 This is a schematic diagram of the rotor structure in one or more embodiments of the present invention.

[0025] Figure 3 This is a schematic diagram of the stator assembly installed inside the outer tube in one or more embodiments of the present invention.

[0026] Figure 4 This is a schematic diagram of the straightening frame in one or more embodiments of the present invention.

[0027] Figure 5 This is a top view schematic diagram of the straightening frame in one or more embodiments of the present invention.

[0028] Figure 6 This is a schematic diagram of the structure of a double-through connector in one or more embodiments of the present invention.

[0029] Figure 7 This is a structural schematic diagram of a connector component in one or more embodiments of the present invention.

[0030] Figure 8 This is a structural schematic diagram of a double-pass component in one or more embodiments of the present invention.

[0031] Figure 9 This is an axial view of the double-pass member in one or more embodiments of the present invention.

[0032] Among them, 1. Pump coupling; 2. Rotor; 3. Centralizing block; 31. Guide claw; 4. Stator assembly; 5. Outer pipe; 51. Annular sand settling space; 6. Intermediate coupling; 7. Limiter; 8. Double-pass connector; 81. Connector component; 82. Double-pass component; 83. Liquid inlet channel; 84. Sand settling channel; 9. Oil pipe coupling; 10. Sand settling tailpipe; 11. Blind plug. Detailed Implementation

[0033] Example 1 In a typical embodiment of the present invention, such as Figures 1-9 As shown, a sedimentation screw pump is presented.

[0034] Currently, the sand-sinking or sand-prevention structures of screw pumps are insufficient to effectively reduce the amount of sand and gravel deposited above the stator. This results in a large amount of sand and gravel flowing back into the stator assembly 4 during the sand and gravel discharge process, causing pump start-up difficulties and abnormal wear. Due to structural limitations, bridging and blockages are also prone to occur in the sand-sinking discharge path, causing the sand-sinking channel 84 to fail and exacerbating the problem of sand and gravel entering the stator assembly 4. Based on this, this embodiment provides a sand-sinking screw pump with an exposed section of rotor 2 that does not cooperate with the stator assembly 4. The centrifugal force of rotor 2 during rotation is used to throw out the sand and gravel in the sand-containing fluid, thereby pre-removing the sand and gravel. A double-connector 8 is provided so that the settled sand and gravel can pass through and fall into the sand-sinking tailpipe 10. The inlet channel 83 and the sand-sinking channel 84 are isolated from each other, thereby reducing the sand concentration in the fluid at the outlet of the stator assembly 4 and reducing the secondary accumulation of settled sand and gravel at the inlet, reducing the probability of the screw pump jamming and reducing wear.

[0035] like Figures 1-9 As shown, the sedimentation screw pump achieves the pumping of fluids and the active separation and collection of sand and gravel through the coordinated configuration of rotor 2, stator assembly 4, outer pipe 5, double-connector 8 and sedimentation tail pipe 10.

[0036] The outer tube 5 is fitted outside the stator assembly 4, forming an annular sand settling space 51 between the stator assembly 4 and the inner wall of the outer tube 5. The lower end of the outer tube 5 is connected to the sand settling tailpipe 10 via a double-connector 8. The rotor 2 is installed inside the stator assembly 4. The upper part of the rotor 2 has an exposed section extending beyond the upper end face of the stator assembly 4. The exposed section is used to generate centrifugal force when rotating to throw sand and gravel toward the inner wall of the outer tube 5 so that it falls into the annular sand settling space 51. The double-connector 8 has a longitudinally penetrating sand settling channel 84 and a fluid inlet channel 83 isolated from the sand settling channel 84. The annular sand settling space 51 is connected to the sand settling tailpipe 10 via the sand settling channel 84, and the fluid inlet channel 83 is connected to the external well fluid and the fluid inlet of the stator assembly 4.

[0037] In a screw pump, the rotor 2 is typically a helical component, installed inside the stator assembly 4, which pressurizes and transports fluid through rotational motion. The stator assembly 4 has an elastic bushing with a helical cavity, which cooperates with the rotor 2 to form a sealed chamber for pumping fluid. The rotor 2 and the stator assembly 4 constitute the core pumping unit of the screw pump, while the outer tube 5 provides external support and protection for the entire unit.

[0038] Specifically, the annular settling space 51 can have a uniform radial width, or its radial width can vary along the axial direction to adapt to different hydrodynamic requirements. The annular settling space mainly provides a channel for the separated sand and gravel to settle downwards.

[0039] The double-connector 8 can be fixed to the outer pipe 5 and the sedimentation tailpipe 10 by means of threaded connection, flange connection, or welding. The sedimentation tailpipe 10 is connected below the double-connector 8 and serves as a container for collecting and storing sand and gravel. The length of the sedimentation tailpipe 10 can be set according to actual application requirements; for example, it can be a single pipe segment or multiple pipe segments connected in series.

[0040] The rotor 2 is installed within the stator assembly 4 to form the pumping mechanism of the screw pump. The exposed section also has a helical structure, and its specific length and diameter can be adjusted according to the characteristics of the pumped fluid and the required centrifugal force.

[0041] When the rotor 2 rotates, the exposed section can disturb the surrounding fluid and generate centrifugal force. As a result, the sand and gravel in the fluid are thrown towards the inner wall of the outer tube 5 under the action of centrifugal force. After being thrown towards the inner wall of the outer tube 5, the sand and gravel will fall along the inner wall of the outer tube 5 into the annular sand settling space 51 and sink, eventually falling into the annular sand settling space 51.

[0042] The liquid inlet channel 83 can be composed of multiple holes or annular chambers and is physically isolated from the sedimentation channel 84 to prevent the sedimented gravel from mixing with the inlet fluid. Gravel descending from the annular sedimentation space 51 can enter the sedimentation channel 84 and further settle into the sedimentation tailpipe 10, ensuring smooth discharge of gravel and avoiding accumulation at the flow channel transition point.

[0043] External well fluid enters through inlet channel 83 and is then guided to the inlet of stator assembly 4, thus entering the pumping chamber of the screw pump. The isolation between inlet channel 83 and sand-retaining channel 84 ensures that the fluid entering the pumping chamber has a low sand content, thereby protecting the normal operation of the screw pump.

[0044] In this embodiment, the screw pump for sand settling actively separates sand and gravel in the well fluid by using an exposed section of rotor 2 above the stator assembly 4 and the centrifugal force generated by its rotation. The sand and gravel are thrown towards the inner wall of the outer pipe 5 and descend along the annular sand settling space 51. Combined with the sand settling channel 84 that runs longitudinally through the double-connector 8 and is isolated from the fluid inlet channel 83, it ensures that the sand and gravel can smoothly settle into the sand settling tailpipe 10, effectively avoiding the risks of sand and gravel falling back and depositing, flow channel blockage, and pump jamming in traditional solutions. As a result, the sand concentration in the fluid at the inlet of the stator assembly 4 is reduced, the wear of sand and gravel on the pump body is reduced, and the operational reliability and service life of the screw pump are improved.

[0045] As the gravel flows down the annular settling space 51, if there is an obstruction in the flow channel of the gravel into the annular settling space 51, it will cause the gravel to accumulate or flow poorly, affecting the settling efficiency. To address this, this embodiment also provides a straightening block 3 installed on the upper end of the stator assembly 4. The straightening block 3 maintains the relative position between the stator assembly 4 and the outer tube 5. The straightening block 3 has multiple radially extending guide claws 31, and an open flow channel is formed between adjacent guide claws 31 for the gravel to pass through and adhere to the inner wall of the outer tube 5.

[0046] Specifically, the centering block 3 ensures that the axis of the stator assembly 4 remains substantially aligned with the axis of the outer tube 5 when it is fitted inside the outer tube 5, thereby maintaining the uniformity of the annular sedimentation space 51. The centering block 3 can be annular, segmented annular, or have a structure with support arms to provide stable support and positioning. The centering block 3 effectively maintains the relative position between the stator assembly 4 and the outer tube 5, ensuring that the annular sedimentation space 51 maintains a relatively uniform width along its entire length. This avoids excessively narrow local flow channels due to the eccentricity of the stator assembly 4, thereby reducing the risk of gravel accumulation within the annular sedimentation space 51 and ensuring smooth downward flow of gravel.

[0047] like Figure 1 and Figure 3 As shown, the outer periphery of the straightening block 3 contacts the inner wall of the outer tube 5, and the inner periphery of the straightening block 3 contacts the outer wall of the stator assembly 4, thereby supporting and positioning the stator assembly 4 in the radial direction.

[0048] like Figure 4 and Figure 5 As shown, the centering block 3 has multiple radially extending guide claws 31. The guide claws 31 are structures extending radially from the centering block 3 for support and guidance. They maintain the relative position of the stator assembly 4 and the outer tube 5 and also guide the downward movement of gravel. Specifically, the guide claws 31 can be blade-shaped, strip-shaped, or columnar, extending radially outward from the main body of the centering block 3. The number of guide claws 31 can be designed according to actual needs, such as three, four, or more, to provide stable support.

[0049] An open flow channel is formed between adjacent guide claws 31, allowing sand and gravel to adhere to the inner wall of the outer pipe 5 and pass through. Because sand and gravel tend to flow downwards along the inner wall of the outer pipe 5 under centrifugal force, the open channel minimizes obstruction to the flow of sand and gravel, preventing bridging or accumulation at the centering block 3. Sufficient gaps are left between the guide claws 31, forming a fan-shaped or near-fan-shaped flow channel. The width and height of the flow channel should be sufficient to allow high-concentration sand-containing fluid to pass through, avoiding dead zones and clogging problems that may occur with traditional filtration structures. This improves the flow efficiency and reliability of the entire sand settling channel 84, ensures the stable operation of the screw pump, and reduces the probability of pump jamming and wear.

[0050] like Figure 1 , Figure 2 As shown, the exposed section drives the fluid to generate a spiral centrifugal force when rotating. The upper end of the guide claw 31 extends above the upper end face of the stator assembly 4, and the guide claw 31 is provided with a guide surface to guide the rotor 2 into the stator assembly 4.

[0051] Helical centrifugal force refers to the phenomenon where, while the fluid moves outward under radial centrifugal force, the helical structure and rotation direction of rotor 2 also cause the fluid to tend to move axially downward under the influence of gravity. Because the helical blades or their surface structure in the exposed section of rotor 2 interact with the fluid during rotation, rotational momentum and axial momentum are transferred to the fluid. By generating helical centrifugal force, sand and gravel in the fluid can be more effectively thrown towards the inner wall of the outer tube 5, and as they are thrown out, they gain a downward helical motion component due to gravity, thus promoting the helical downward movement of the sand and gravel along the inner wall of the outer tube 5.

[0052] The upper end of the guide claw 31 extends above the upper end face of the stator assembly 4, thereby expanding the effective working area of ​​the guide claw 31 upward and covering the initial area of ​​the exposed section of the rotor 2 for centrifugal separation. This allows the guide claw 31 to intervene in the guidance process of the sand earlier. When the sand is just thrown towards the inner wall of the outer tube 5 by the exposed section, it can be blocked by the guide claw 31 and guided into the annular sand settling space 51. This helps to prevent the sand from forming eddies or accumulating near the upper end face of the stator assembly 4, ensuring that the sand can smoothly descend along the inner wall of the outer tube 5 and reducing the risk of the sand re-entering the main fluid flow.

[0053] The guide claw 31 is provided with a guide surface to guide the rotor 2 into the stator assembly 4. The guide surface is a smooth surface with an inclination or curvature. When the rotor 2 is inserted into the stator assembly 4, the front end of the rotor 2 is guided to enter the inner cavity of the stator assembly 4 accurately and smoothly, which improves assembly efficiency and safety, and ensures that the rotor 2 is correctly aligned in the stator assembly 4, thereby ensuring the normal operation performance of the pump.

[0054] like Figure 6 , Figure 7 and Figure 8 As shown, the double-port connector 8 includes a double-port housing and a double-port component 82. The double-port housing serves as the external structure of the double-port connector 8, with its upper end connected to the outer pipe 5 and its lower end connected to the sand-removing pipe, and is externally fitted over the double-port component 82. The double-port component 82 is fixed inside the double-port housing, and the outer wall of the double-port housing provides structural strength and sealing, protecting the double-port component 82. A fluid inlet channel 83 is formed on the double-port component 82. To allow external well fluid to enter the fluid inlet channel 83 on the double-port component 82, an inlet hole communicating with the fluid inlet channel 83 is provided on the side wall of the double-port housing. The inlet hole is aligned with and communicates with the fluid inlet channel 83 on the double-port component 82, thus forming a continuous fluid inlet path from the external environment to the internal fluid inlet channel 83 of the double-port component 82.

[0055] like Figure 6 , Figure 8 and Figure 9 As shown, the double-through connector 8 has a longitudinally penetrating sand-collecting channel 84 and a liquid inlet channel 83 isolated from the sand-collecting channel 84. The liquid inlet channel 83 is formed on the double-through component 82, and a liquid inlet hole communicating with the liquid inlet channel 83 is formed on the side wall of the double-through housing. The double-through connector 8 also includes a connector component 81, which connects the liquid inlet channel 83 and the liquid inlet of the stator assembly 4.

[0056] The connector component 81 provides a transition path between the fluid inlet channel 83 inside the double-connector 8 and the fluid inlet of the stator assembly 4. The connector component 81 can be a tubular or irregularly shaped connector with specific shapes and sizes, its two ends respectively mate with the fluid inlet channel 83 and the fluid inlet of the stator assembly 4. In terms of material selection, corrosion-resistant metal materials (such as stainless steel or alloy steel) or high-strength engineering plastics can be selected according to the corrosiveness and pressure requirements of the downhole environment. To ensure the sealing of the connection, the connector component 81 is usually used with sealing rings (such as O-rings) or a conical seal structure. Furthermore, the connector component 81 can also be connected via threaded connections, flange connections, or snap-fit ​​connections, depending on the ease of assembly and disassembly requirements.

[0057] Specifically, such as Figure 6 and Figure 9 As shown, the settling channel 84 inside the double-through joint 8 is a straight hole extending along the axis of the double-through component 82. By configuring the settling channel 84 as a straight hole extending along the axis, the gravel can settle directly under gravity, reducing the resistance to the downward movement of the gravel and ensuring the continuity of the settling process.

[0058] The settling channel 84 guides the centrifugally separated sand and gravel downwards from the annular settling space 51 and ultimately into the settling tailpipe 10, preventing sand and gravel from accumulating or clogging in the double-pass joint 8 area. The settling channel 84 extends along the axis of the double-pass component 82, specifically, the centerline of the settling channel 84 coincides with or is parallel to the axis of the double-pass component 82. The settling channel 84 can be formed by machining inside the double-pass component 82, for example, by drilling, boring, or casting followed by finishing. The inner wall of the straight hole can be polished or made of wear-resistant material to reduce frictional resistance. The diameter of the straight hole should be configured according to the expected sand and gravel particle size and flow rate to effectively prevent bridging even under high sand content conditions.

[0059] In addition, such as Figure 8 and Figure 9As shown, the sedimentation channels 84 in this embodiment can be configured as multiple channels, which can be arranged at intervals according to requirements. For example, multiple sedimentation channels 84 can be distributed in a straight or curved array, or distributed at intervals around the axis of the double-pass component 82, so as to adapt to the annular sedimentation space 51 above it, so that the sand and gravel falling along the ring in the annular sedimentation space 51 can be diverted to multiple sedimentation channels 84, and sink down along the sedimentation channels 84, pass through the double-pass connector 8, and smoothly enter the sedimentation tailpipe 10.

[0060] The settling channel 84 within the double-through joint 8 is configured as a straight hole extending along the axis of the double-through component 82. This simplifies the movement path of the sand and eliminates potential obstructions, dead angles, or diameter change areas that may exist in traditional curved or complex channels, thereby reducing the frictional resistance and collision probability of the sand and gravel moving within the channel. Since the sand and gravel primarily descend under gravity, the straight hole structure utilizes gravitational potential energy to ensure direct and rapid settling, reducing energy loss and velocity reduction caused by channel tortuosity. This effectively prevents the risk of bridging, accumulation, or blockage of high-concentration sand-containing fluid in the area of ​​the double-through joint 8.

[0061] like Figure 1 As shown, the liquid inlet of the stator assembly 4 is formed by the limiter 7. The upper end of the limiter 7 is connected to the lower end of the stator assembly 4 through the intermediate clamp 6, and the lower end of the limiter 7 is connected to the double-through connector 8.

[0062] The limiter 7 employs a structure adapted to the inlet size of the stator assembly 4 and the mating position size of the double-connector 8, such as a cylindrical or annular structure. The inner diameter and length of the limiter 7 are selected according to the size of the mating position and the distance between the stator assembly 4 and the double-connector 8. The inner wall of the limiter 7 is smooth to reduce fluid resistance. In some embodiments, the limiter 7 may be made of a wear-resistant material to withstand long-term scouring by sand-containing fluids.

[0063] The upper end of the limiter 7 is connected to the lower end of the stator assembly 4 via an intermediate clamp 6. The intermediate clamp 6 serves as a connecting component to achieve both mechanical connection and fluid sealing between the limiter 7 and the stator assembly 4. The intermediate clamp 6 can be fixed to the limiter 7 and the stator assembly 4 using methods such as threaded connection, flange connection, or welding. For example, the two ends of the intermediate clamp 6 can be machined with internal and external threads respectively to allow for threaded connection with the limiter 7 and the lower end of the stator assembly 4, ensuring a firm and airtight connection and preventing fluid leakage or sand intrusion.

[0064] The lower end of the limiter 7 is connected to the double-through connector 8. The lower end of the limiter 7 is connected to the double-through connector 8 to establish a direct and continuous fluid passage from the fluid inlet channel 83 of the double-through connector 8 to the fluid inlet of the stator assembly 4, so that the well fluid in the fluid inlet channel 83 can smoothly pass through the limiter 7 and enter the stator assembly 4. In order to ensure the sealing of the connection position, the connection can be achieved by precision machining, or the sealing effect can be enhanced by auxiliary structures such as sealing rings.

[0065] like Figure 1 and Figure 3 As shown, the sand-sinking tailpipe 10 is composed of multiple sections of tubing connected together, and a blind plug 11 is provided at the bottom of the sand-sinking tailpipe 10. The sand-sinking tailpipe 10 can be composed of multiple sections of standard tubing connected in series by means of threaded connection, etc. The modular design allows the overall length and internal volume of the sand-sinking tailpipe 10 to be flexibly adjusted according to the actual sand content of the oil well and the expected sand-sinking cycle.

[0066] For example, in oil wells with high sand content, more tubing segments can be connected in series to increase sand-settling capacity and extend service life; while in oil wells with low sand content, the number of tubing segments can be reduced to lower costs and simplify downhole operations. The blind plug 11 is used to seal the lower end of the sand-settling tailpipe 10, ensuring that the sand and accompanying fluids settled within are effectively trapped, preventing them from re-entering the wellbore or mixing with the well fluid, thereby maintaining the stability of the sand-settling effect.

[0067] like Figure 1 As shown, a pump coupling 1 is installed at the top of the outer pipe 5. The pump coupling 1 can have a ring-shaped or cylindrical structure to facilitate the connection between the outer pipe 5 and external pipelines. To facilitate the connection between the pump coupling 1, the outer pipe 5, and the external pipelines, corresponding snap-fit ​​connections or threads can be provided on the pump coupling 1 and the outer pipe 5, so that the pump coupling 1 and the upper end of the outer pipe 5 are connected by snap-fit ​​or threaded engagement, forming a good connection and seal. The sealing effect can also be enhanced by adding sealing gaskets or sealing rings. The size and specifications of the pump coupling 1 are adapted to the outer pipe 5 and the external pipelines. The pump coupling 1 can be sleeved on the outer pipe 5 and the external pipelines for connection, or one end of the pump coupling 1 can be externally threaded to fit the internal thread provided on the upper end of the outer pipe 5, thereby establishing an embedded connection with the outer pipe 5.

[0068] Example 2 In another typical embodiment of the present invention, such as Figures 1-9 As shown, a method for operating a sedimentation screw pump is provided, utilizing the sedimentation screw pump as described in Example 1, including the following steps: The rotor 2 is driven to rotate, and the external well fluid enters through the inlet channel 83, which is isolated from the sand-falling channel 84, inside the double-through connector 8, and is transported to the inlet of the stator assembly 4, and is transported upward under the drive of the rotor 2; The exposed section extending from the upper part of the rotor 2 to the upper end of the stator assembly 4 drives the fluid to rotate, generating centrifugal force and throwing the sand and gravel in the fluid toward the inner wall of the outer tube 5. The thrown-out gravel flows down along the annular sedimentation space 51 formed between the inner wall of the stator assembly 4 and the outer tube 5, passes through the longitudinally penetrating sedimentation channel 84 in the double-through joint 8, and settles into the sedimentation tail pipe 10 for storage.

[0069] Specifically, in the step of driving rotor 2 to rotate, rotor 2 is driven by an external power source, which can be a downhole motor or a surface drive device. Its rotational motion drives the screw pump to produce a pumping action. The external well fluid, i.e., the sand-containing fluid to be treated, first enters through the inlet channel 83 in the double-port connector 8. This inlet channel 83 is physically isolated from the sand settling channel 84, ensuring that the well fluid does not mix with the separated sand and gravel before entering the pumping area. The well fluid is then delivered to the inlet of the stator assembly 4, where it is drawn by the rotating rotor 2. Under the synergistic action of rotor 2 and stator assembly 4, the fluid is forced upward, beginning its journey within the pump. This process ensures a continuous supply of fluid and the start-up of the pump.

[0070] The centrifugal force generated by the exposed section of the rotor 2 extending from the upper end face of the stator assembly 4 drives the fluid to rotate, throwing sand and gravel in the fluid toward the inner wall of the outer pipe 5. When the fluid is pumped to the vicinity of the upper end face of the stator assembly 4, the exposed section of the rotor 2 directly contacts the fluid, generating centrifugal force. Since the density of sand and gravel is usually greater than that of fluid, under the action of centrifugal force, the sand and gravel will preferentially be thrown toward the inner wall of the outer pipe 5, achieving preliminary separation of fluid and sand and gravel. This separates most of the sand and gravel from the main fluid, preventing it from entering the pumping chamber inside the stator assembly 4, thereby reducing the sand concentration in the pumped fluid.

[0071] When the gravel reaches the area of ​​the double-through joint 8, it passes through the specially designed longitudinally continuous sedimentation channel 84 inside the double-through joint 8. The gravel enters the sedimentation tailpipe 10 through the sedimentation channel 84 for centralized storage, thereby achieving the separation of the gravel from the pumping fluid.

[0072] The length of the sand-sinking tailpipe 10 is determined in advance based on the sand content of the oil well, and the sand-sinking tailpipe 10 is constructed by connecting different numbers of oil pipes in series to match the sand storage requirements of the oil well.

[0073] Before the sand-falling screw pump is put into operation, the actual or predicted sand content data of the target oil well is analyzed to assess and plan the required effective volume of the sand-falling tailpipe 10. The sand content characteristics of the oil well can be obtained by comprehensively analyzing various information sources such as geological exploration reports, historical production data, and well test results. Based on this data, combined with the expected continuous operating cycle of the sand-falling screw pump and its sand-falling efficiency, the required total length of the sand-falling tailpipe 10 can be calculated. For example, if the daily sand production of a certain oil well is known to be a specific value, and it is expected that the sand-falling screw pump can operate continuously and stably for a preset period of time, then the minimum volume of the sand-falling tailpipe 10 should be able to meet the storage requirements of all settled sand and gravel during this period.

[0074] Oil pipes are standard pipes widely used in the petroleum industry. For example, standard oil pipe sections of different lengths (such as 2.5 meters, 5 meters, 7.5 meters, or 10 meters) or the same length but different quantities can be selected and connected using fittings such as oil pipe couplings 9, thereby flexibly assembling the required total length of the sand-sinking tailpipe 10. The modular and configurable design allows the length of the sand-sinking tailpipe 10 to be precisely adjusted according to predetermined storage requirements.

[0075] For oil wells with high sand content, more tubing can be connected in series to significantly increase the length of the sand-sinking tailpipe 10, thereby providing greater sand and gravel storage space and effectively extending the time interval between two well workover operations. Conversely, for oil wells with low sand content, a shorter sand-sinking tailpipe 10 can be configured to avoid unnecessary material waste and the complexity of downhole operations.

[0076] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A sedimentation screw pump, characterized in that, Includes rotor, stator assembly, outer tube, double-connector, and sand-filled tailpipe; The outer tube is sleeved outside the stator assembly, and an annular sand settling space is formed between the stator assembly and the inner wall of the outer tube; the lower end of the outer tube is connected to the sand settling tail tube through a double-connector. The rotor is installed inside the stator assembly. The upper part of the rotor has an exposed section extending out of the upper end face of the stator assembly. The exposed section is used to drive the fluid to generate centrifugal force during rotation to throw the sand and gravel towards the inner wall of the outer tube so that it falls into the annular sand settling space. The dual-connector has a longitudinally connected sand settling channel and a fluid inlet channel isolated from the sand settling channel; the annular sand settling space is connected to the sand settling tailpipe via the sand settling channel, and the fluid inlet channel is connected to the external well fluid and the fluid inlet of the stator assembly.

2. The sedimentation screw pump as described in claim 1, characterized in that, It also includes a centering block located at the top of the stator assembly. The centering block maintains the relative position between the stator assembly and the outer tube. The centering block has multiple radially extending guide claws, and an open flow channel is formed between adjacent guide claws to allow gravel to adhere to the inner wall of the outer tube and pass through.

3. The sedimentation screw pump as described in claim 2, characterized in that, When the exposed section rotates, it drives the fluid to generate a spiral centrifugal force. The upper end of the guide claw extends above the upper surface of the stator assembly, and the guide claw is provided with a guide surface to guide the rotor into the stator assembly.

4. The sedimentation screw pump as described in claim 1, characterized in that, The double-pass connector includes a double-pass shell and a double-pass component. The upper end of the double-pass shell is connected to an outer pipe, the lower end is connected to a sand-collecting pipe, and it is sleeved on the double-pass component. The liquid inlet channel is opened on the double-pass component, and the side wall of the double-pass shell is provided with a liquid inlet hole that communicates with the liquid inlet channel.

5. The sedimentation screw pump as described in claim 4, characterized in that, The dual-connector also includes a connector component, which connects the liquid inlet channel and the liquid inlet of the stator assembly.

6. The sedimentation screw pump as described in claim 4 or 5, characterized in that, The sand-collecting channel inside the double-through joint is a straight hole that runs through the axis of the double-through component.

7. The sedimentation screw pump as described in claim 1, characterized in that, The liquid inlet of the stator assembly is formed by a limiter. The upper end of the limiter is connected to the lower end of the stator assembly through a middle clamp, and the lower end of the limiter is connected to a double-through connector.

8. The sedimentation screw pump as described in claim 1, characterized in that, The sand-sinking tailpipe is composed of multiple sections of oil pipe connected together, and a blind plug is provided at the bottom of the sand-sinking tailpipe.

9. A method for operating a sedimentation screw pump, utilizing the sedimentation screw pump as described in any one of claims 1-8, characterized in that, include: The rotor is driven to rotate, and the external well fluid enters through the inlet channel inside the double-through joint, which is isolated from the sand-settling channel, and is transported to the inlet of the stator assembly, where it is transported upward under the drive of the rotor. The exposed section extending from the upper part of the rotor to the upper end face of the stator assembly drives the fluid to rotate, generating centrifugal force and throwing the sand and gravel in the fluid toward the inner wall of the outer tube. The ejected gravel descends along the annular sedimentation space formed between the stator assembly and the inner wall of the outer tube, passes through the longitudinally penetrating sedimentation channel inside the double-connector, and settles into the sedimentation tailpipe for storage.

10. The operating method of the sedimentation screw pump as described in claim 9, characterized in that, The length of the sand-sinking tailpipe is determined in advance based on the sand content of the oil well, and different numbers of oil pipes are connected in series to form the sand-sinking tailpipe to match the sand storage requirements of the oil well.

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