A double-pump system based on a screw drive electric submersible pump and a control method thereof

Abstract

The application belongs to the technical field of oil and gas exploitation and booster delivery pump, and discloses a double-pump system based on a screw rod driving submersible electric pump and a control method thereof. The system comprises: an upper pump system installed on the upper part of a motor system and used for completing oil suction and discharge processes through driving power of the motor system; a lower pump system installed on the lower part of the motor system and used for completing the oil discharge and suction processes through driving power of the motor system and synchronous reverse operation with the upper pump system; and a motor system used for completing the oil suction and discharge processes of the upper and lower pump systems through provided driving power. Compared with the traditional motor direct drive mode, the screw rod driving mode has higher energy utilization rate. The system can be long-term and stable operated in deep well, high pressure, high temperature or high viscosity environment, effectively adapts to complex working conditions, and reduces maintenance cost.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of oil and gas exploitation and booster delivery pump, and particularly relates to a double-pump system based on a lead screw driven electric submersible pump and a control method thereof. BACKGROUND

[0002] In the process of oilfield exploitation, electric submersible pump systems are widely used for deep well liquid lifting to improve oil well productivity. In deep well, high pressure or high viscosity fluid working conditions, the traditional electric submersible pump system faces many challenges, such as limited head, high energy consumption, large axial force and high maintenance cost. The head of a single-stage pump is limited, and if a higher liquid level needs to be lifted, the number of pump stages usually needs to be increased, but too many stages not only reduce system efficiency, but also increase mechanical loss. The traditional electric submersible pump mainly relies on the direct drive of the motor to drive the impeller or screw, and the long shaft transmission structure often leads to large power loss, and due to the unbalanced liquid pressure, it is easy to produce excessive axial force, aggravate equipment wear and tear, and shorten the service life.

[0003] Cascade pumps realize higher head and flow by connecting two or more stages of pumps in series to adapt to deep well and high viscosity working conditions. Most of the existing double-pump systems have an upper and lower distributed structure, which causes the center of gravity of the system to deviate, making it inconvenient to install underground and affecting its running stability. The traditional motor is usually placed at the top or bottom of the system, which causes the transmission chain to be long, thereby increasing mechanical loss and failure rate. In the harsh environment of high temperature and high pressure underground, the traditional motor driving mode has the risk of overload and poor cooling effect, affecting the long-term running stability. SUMMARY

[0004] To overcome the problems in the related art, the present application provides a double-pump system based on a lead screw driven electric submersible pump and a control method thereof. The present application realizes the suction and discharge of liquid by rotating the lead screw to drive the polished rod to reciprocate and then make the plunger reciprocate linearly. The system can adapt to the complex environment of the seabed and can operate efficiently and stably in the case of high viscosity and multiphase fluid.

[0005] The technical solution is as follows: a double-pump system based on a lead screw driven electric submersible pump, comprising:

[0006] An upper pump system installed at the upper part of the motor system and used to complete the oil suction and discharge processes through the driving power of the motor system;

[0007] A lower pump system installed at the lower part of the motor system and used to complete the oil discharge and suction processes through the driving power of the motor system and in reverse operation synchronously with the upper pump system;

[0008] The motor system, by providing driving power, completes the oil suction and discharge processes of the upper and lower pump systems.

[0009] Further, the upper pump system comprises an oil pipe, an upper pump oil inlet cavity cover plate, an upper pump oil inlet valve, an upper pump oil discharge valve, an upper pump working cavity end cover, an upper pump cylinder body, an upper pump plunger, an upper pump lower end cover, and a hose;

[0010] The upper pump oil inlet cavity cover plate is installed on the top of the upper pump cylinder body;

[0011] The upper pump oil inlet cavity cover plate and the upper pump working cavity end cover form an oil discharge cavity therebetween;

[0012] The oil discharge cavity, together with the upper pump oil inlet cavity cover plate and the upper pump working cavity end cover, forms an upper oil inlet cavity, the upper pump plunger and the upper pump working cavity end cover form an upper working cavity, and the upper pump plunger and the upper pump lower end cover form a lower cavity; the upper pump plunger is movably accommodated in the upper pump cylinder body;

[0013] The upper pump working cavity end cover is installed on the upper end of the upper pump cylinder body, and a one-way closed upper pump oil inlet valve is fixed in the upper oil inlet cavity;

[0014] A one-way closed upper pump oil discharge valve is fixed in the oil discharge cavity;

[0015] The upper pump lower end cover is installed on the bottom of the upper pump cylinder body.

[0016] The upper pump working cavity end cover is provided with an upper oil inlet passage for communicating the upper oil inlet cavity and the upper working cavity, and is provided with an oil discharge passage for communicating the upper working cavity and the oil discharge cavity.

[0017] The upper pump oil discharge valve is installed on the upper part of the oil discharge passage; the oil discharge passage is in the shape of a semi-circular ring.

[0018] Static sealing devices are arranged between the upper pump oil inlet cavity cover plate and the upper pump cylinder body, and between the upper pump working cavity end cover and the upper pump cylinder body;

[0019] The upper end of the hose is provided with an upper through hole; the oil pipe is internally provided with a lower pump oil discharge valve of a lower pump system; and the upper through hole is communicated with the oil pipe through the lower pump oil discharge valve.

[0020] The upper end of the hose is threadedly connected with the upper pump oil inlet cavity cover plate; the hose is fixed by a metal support and a clamp; and a limit detection device for monitoring the vibration state of the hose in real time is arranged in the middle of the hose.

[0021] The upper pump oil inlet cavity cover plate and the upper pump working cavity end cover are provided with an oil inlet hole communicated with the hose;

[0022] The hose is used for connecting a lower pump oil discharge port of the lower pump system and the oil pipe;

[0023] The dynamic sealing device is sealed by a V-shaped sealing ring matched with a check ring, and a dustproof ring and a sand throwing ring are arranged outside for multi-layer protection.

[0024] The motor system comprises an upper pump light rod, a screw rod, a screw nut, a motor rotor, a motor stator, a motor shell, and a lower pump light rod.

[0025] The motor stator is installed on the motor shell.

[0026] The screw nut is fixedly connected with the motor rotor through a spline, and drives the screw nut to drive the screw rod to reciprocate.

[0027] The lower pump system comprises a lower pump plunger connected with the lower pump light rod of the motor system, and the lower pump plunger is freely slidably accommodated in a lower pump cylinder body.

[0028] The lower pump cylinder body is provided with a lower pump liquid discharge between the lower pump cylinder body and a lower working cavity end cover.

[0029] The lower pump plunger and the lower working cavity end cover form a lower pump working cavity.

[0030] The lower working cavity end cover and the lower pump oil inlet cavity cover plate are provided with a lower pump liquid inlet between them.

[0031] The lower working cavity end cover and the lower pump oil inlet cavity cover plate form a lower pump liquid inlet cavity.

[0032] The lower pump liquid inlet cavity contains a lower pump liquid inlet valve installed on the lower working cavity end cover.

[0033] The lower working cavity end cover is provided with a lower pump oil liquid conveying channel communicating with the lower pump working cavity and the lower pump liquid inlet cavity.

[0034] Static sealing devices are arranged between the lower pump oil inlet cavity cover plate and the lower pump cylinder body, and between the lower working cavity end cover and the lower pump cylinder body.

[0035] The lower pump light rod of the motor system and the lower pump cylinder body are sealed by a dynamic sealing device, and the dynamic sealing device is sealed by a V-shaped sealing ring matched with a check ring, and a dustproof ring and a sand throwing ring are arranged outside for multi-layer protection.

[0036] Another object of the present application is to provide a control method of a double pump system based on a screw rod driven submersible electric pump, which comprises the following steps:

[0037] The screw nut is fixedly connected to the hollow motor rotor through a spline, the motor rotor drives the screw nut to rotate forward and reversely, thereby driving the screw threadedly matched screw rod to move linearly in the axial direction, the upper part of the screw rod is an upper pump light rod, the upper pump light rod is connected with an upper pump plunger, the up-down reciprocating movement of the upper pump plunger realizes the periodic change of the volume of the motor integrated pump cylinder, when the screw rod reverses, the upper pump light rod moves downward, driving the upper pump plunger to move downward, the volume of the upper working chamber increases, under the action of the pressure difference, the oil enters the upper working chamber through the upper pump liquid inlet valve, the suction process of the upper pump system is completed, at the same time, the lower pump light rod moves downward, driving the lower pump plunger to move downward, the volume of the lower pump working chamber decreases, the oil pressure increases, the oil is discharged through the hose, and the discharge process of the lower pump system is completed.

[0038] When the screw rod rotates forward, the upper pump light rod moves upward, driving the upper pump plunger to move upward, the volume of the upper working chamber decreases, the oil pressure increases, the oil is discharged through the upper pump liquid outlet valve, the discharge process of the upper pump system is completed, at the same time, the lower pump light rod moves upward, driving the lower pump plunger to move upward, under the action of the pressure difference, the oil enters the lower pump working chamber through the lower pump liquid inlet valve, the suction process of the lower pump system is completed.

[0039] The upper pump system and the lower pump system are in the continuous suction process and the discharge process, a limit detection device is arranged in the middle of the hose, for monitoring the vibration state of the hose in real time, when the shaking amplitude or frequency exceeds the set threshold value, the control system issues an alarm or executes a speed reduction or shutdown operation.

[0040] In combination with all the technical solutions described above, the present application has the following beneficial effects:

[0041] Firstly, the present application is based on a screw rod driven submersible electric pump double pump system, which comprises a tubing, an oil inlet cavity cover plate, a liquid inlet valve, a liquid outlet valve, an upper working chamber end cover, a cylinder body, a plunger, a light rod, an upper pump lower end cover, a motor system, a hose and a lower pump liquid outlet valve, the screw rod is driven to rotate up and down reciprocating movement by the motor, the light rod is driven to move by the plunger in the form of the screw rod driving the light rod, so as to realize oil and gas lifting and conveying, and ensure high energy efficiency, high displacement conveying of multi-phase fluids such as high viscosity, gas-liquid mixed phase, high solid impurity containing crude oil and the like under high sand content and various chemical environments.

[0042] Secondly, the present application adopts a screw rod driving technology and a motor centrally arranged, and the two pumps are respectively located at the upper and lower ends of the motor. The design reduces the overall gravity center of the system, so that the motor can efficiently drive the double pump work through the screw rod mechanism. The screw rod driving system adopts a screw transmission structure to convert the rotary motion of the screw rod into linear motion. Compared with the traditional motor direct drive mode, the screw rod driving mode has higher energy utilization rate, the system can be stably operated for a long time under deep well, high pressure, high temperature or high viscosity environment, effectively adapts to complex working conditions, and reduces maintenance cost.

[0043] Third, compared with the traditional motor direct drive, the energy utilization rate of the screw drive is higher, and the energy consumption is lower; The system can adapt to complex working conditions such as deep well and high pressure; The structural design of the double pump can improve the oil delivery efficiency, increase the production capacity, and promote the upgrading of oil and gas exploitation equipment. The traditional submersible electric pump has problems such as limited head, insufficient energy utilization rate, and poor reliability, and most of the existing cascade pumps have unreasonable structure. The present application solves the above technical difficulties with the innovative structure of "motor centering + double pump screw drive".

[0044] Fourth, for a long time, in complex environments such as deep well and high viscosity, submersible electric pumps have low efficiency, pump body is easy to wear, and maintenance is difficult. The double pump system based on the screw drive submersible electric pump proposed in the present application combines its optimized sealing design to realize long-term stable operation in such environment, and solves this industry problem. And it is generally believed that the sealing of screw drive is difficult, and it is not suitable for complex environment in the well. The present application uses the indirect transmission structure design of "screw-rod-plunger" to convert the sealing of screw to the sealing of rod, while retaining the high efficiency driving characteristics of screw drive, proving its applicability and efficiency in the well. BRIEF DESCRIPTION OF DRAWINGS

[0045] The accompanying drawings, which are incorporated into the specification and constitute part of it, illustrate embodiments consistent with the present disclosure and, together with the specification, serve to explain the principles of the present disclosure;

[0046] Fig. 1 is a schematic diagram of the double pump system based on the screw drive submersible electric pump provided by the embodiment of the present application;

[0047] Fig. 2 is a schematic diagram of the motor system provided by the embodiment of the present application;

[0048] In the figure:

[0049] 1, oil pipe; 2, upper pump oil inlet cavity cover plate; 3, upper pump liquid inlet valve; 4, upper pump liquid outlet valve; 5, upper working chamber end cover; 6, upper pump cylinder body; 7, upper pump plunger; 8, dynamic sealing device; 9, upper pump lower end cover;

[0050] 10, motor system; 101, upper pump rod; 102, screw; 103, screw nut; 104, motor rotor; 105, motor stator; 106, motor housing; 107, lower pump rod;

[0051] 11, hose; 12, lower pump liquid outlet valve; 13, upper through hole; 14, liquid inlet hole; 15, upper liquid inlet passage; 16, liquid outlet passage; 17, lower pump plunger; 18, lower pump cylinder body; 19, lower working chamber end cover; 20, lower pump liquid outlet; 21, lower pump oil inlet cavity cover plate; 22, lower pump liquid inlet; 23, lower pump liquid inlet valve; 24, lower pump oil liquid conveying passage;

[0052] A1, upper inlet chamber; A2, lower pump inlet chamber; B1, upper working chamber; B2, lower pump working chamber; C, discharge chamber. DETAILED DESCRIPTION

[0053] In order to make the above objectives, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application are described in detail below with reference to the drawings. In the following description, a large number of specific details are set forth in order to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the scope of the present application, so the present application is not limited to the specific embodiments disclosed below.

[0054] The innovation of the present application is that the motor position is placed in the middle of the system, the upper pump system and the lower pump system are respectively installed on the upper and lower parts of the motor system 10, the lead screw 102 is integrally machined with the upper and lower pump light rods 107, the rotation reciprocating motion of the lead screw 102 is realized by the spline connection of the lead screw nut 103 and the motor rotor 104, and the double pump is driven to complete the suction and discharge process synchronously; at the same time, the sealing device and the vibration monitoring mechanism are optimized, compared with the traditional cascade pump mode, the energy utilization rate is higher, and the system can adapt to complex working conditions such as deep well and high pressure, and solves the problems of gravity deviation and large transmission loss of the traditional system.

[0055] In embodiment 1, the double pump system based on the lead screw driven submersible electric pump provided by the present application comprises:

[0056] The upper pump system is installed on the upper part of the motor system 10 and is used to complete the oil suction process and the discharge process by the driving power of the motor system 10;

[0057] The lower pump system is installed on the lower part of the motor system 10 and is used to complete the discharge process and the oil suction process by the driving power of the motor system 10 and the reverse operation synchronously with the upper pump system;

[0058] The motor system 10 completes the oil suction process and the discharge process of the upper pump system and the lower pump system by the driving power provided.

[0059] As shown in Figs. 1-2 The upper pump system comprises an oil pipe 1, an upper pump inlet chamber cover plate 2, an upper pump inlet valve 3, an upper pump discharge valve 4, an upper working chamber end cover 5, an upper pump cylinder body 6, an upper pump plunger 7, an upper pump lower end cover 9 and a hose 11;

[0060] The upper pump inlet chamber cover plate 2 is installed on the top of the upper pump cylinder body 6, and the upper through hole 13 is formed in the upper part of the hose 11; the oil pipe 1 is internally provided with the lower pump discharge valve 12 of the lower pump system; the upper through hole 13 is communicated with the oil pipe 1 through the lower pump discharge valve 12;

[0061] The hose 11 is used to connect the lower pump drain port 20 of the lower pump system and the oil pipe 1 to realize the delivery of oil.

[0062] An inlet hole 14 communicating with a hose 11 is provided between the upper pump inlet chamber cover plate 2 and the upper working chamber end cover 5 to control the inlet and outlet flow of oil.

[0063] A drain chamber C is formed between the upper pump inlet chamber cover plate 2 and the upper working chamber end cover 5;

[0064] The drain chamber C, together with the upper pump inlet chamber cover 2 and the upper working chamber end cover 5, forms the upper inlet chamber A1; the upper pump plunger 7 and the upper working chamber end cover 5 form the upper working chamber B1; and the upper pump plunger 7 and the upper pump lower end cover 9 form the lower chamber. The upper pump plunger 7 is movably housed within the upper pump cylinder 6.

[0065] The upper pump plunger 7 reciprocates within the upper working chamber B1 to achieve the intake and discharge of liquid.

[0066] The upper working chamber end cover 5 is installed on the upper end of the upper pump cylinder 6, and a one-way closing upper pump inlet valve 3 is fixed in the upper inlet chamber A1.

[0067] A one-way closing upper pump drain valve 4 is fixed inside the drain chamber C.

[0068] The lower end cover 9 of the upper pump is installed at the bottom of the upper pump cylinder 6, providing support for the upper pump guide rod 101 of the motor system 10, so that the upper pump guide rod 101 can stably drive the upper pump plunger 7 to move up and down. The upper pump plunger 7 is installed inside the upper pump cylinder 6 and is driven by the upper pump guide rod 101 to realize reciprocating up and down movement;

[0069] The upper working chamber end cap 5 is provided with an upper liquid inlet channel 15 for connecting the upper liquid inlet chamber A1 and the upper working chamber B1; and a liquid outlet channel 16 for connecting the upper working chamber B1 and the liquid outlet chamber C.

[0070] The upper pump drain valve 4 is installed at the upper part of the drain channel 16; the drain channel 16 is semi-circular.

[0071] For example, a static sealing device is provided between the upper pump inlet chamber cover plate 2 and the upper pump cylinder 6 to prevent oil leakage; a static sealing device is provided between the upper working chamber end cover 5 and the upper pump cylinder 6.

[0072] For example, such as Fig. 2 As shown, the motor system 10 includes an upper pump guide rod 101, a lead screw 102, a lead screw nut 103, a motor rotor 104, a motor stator 105, a motor housing 106, and a lower pump guide rod 107. The lead screw 102 is integrally machined with the upper pump guide rod 101 and the lower pump guide rod 107, and the lead screw 102 and the lead screw nut 103 achieve linear reciprocating motion through threaded engagement.

[0073] The upper pump light rod 101 of the motor system 10 is sealed from the upper pump lower end cover 9 by a dynamic sealing device 8. The dynamic sealing device 8 is sealed by a V-shaped sealing ring cooperating with a retaining ring. A dustproof ring and a sand throwing ring are arranged on the outside to achieve multi-layer protection, prevent oil and impurities from flowing into the motor system 10, and improve the service life.

[0074] The motor stator 105 is installed on the motor housing 106.

[0075] The lead screw 102 is designed to have a length greater than the stroke of the upper pump plunger 7. The lead screw nut 103 is fixedly connected to the motor rotor 104 through a spline. A forward and reverse logic is set in the servo motor, which is switched by a controller to realize forward and reverse rotation, thereby driving the lead screw nut 103 to drive the lead screw 102 to move reciprocally. In combination with the limiting device, the motor system 10 can accurately control the movement stroke, speed and reversing time of the plunger, and ensure the synchronization of the double pump suction and discharge.

[0076] The upper end of the hose 11 is threadedly connected to the upper pump oil inlet cavity cover plate 2, and the lower end of the hose 11 is connected to the lower pump cylinder body 18 through a threaded joint and a high-pressure clamp. The connection is stable and convenient for maintenance. The hose 11 is fixed by a metal bracket and a clamp. In order to prevent the hose 11 from shaking during operation, a limiting detection device is arranged in the middle of the hose 11 to monitor the vibration state of the hose 11 in real time, and transmit the data to the control system. The control system presets a shaking amplitude threshold value. When the shaking amplitude or frequency exceeds the set threshold value, the control system can issue an alarm or perform a speed reduction or shutdown operation, thereby improving the stability and reliability of the system.

[0077] As shown in Fig. 1 , Fig. 2 ,

[0078] The lower pump system comprises a lower pump plunger 17 connected to a lower pump light rod 107; the lower pump plunger 17 is freely slidably accommodated in a lower pump cylinder body 18;

[0079] A lower pump liquid discharge port 20 is formed between the lower pump cylinder body 18 and a lower working cavity end cover 19; the lower pump liquid discharge port 20 is communicated with the oil pipe 1 through the hose 11; and the liquid is delivered to the ground;

[0080] The lower pump plunger 17 and the lower working cavity end cover 19 form a lower pump working cavity B2;

[0081] A lower pump liquid inlet port 22 is formed between the lower working cavity end cover 19 and a lower pump oil inlet cavity cover plate 21;

[0082] The lower working cavity end cover 19 and the lower pump oil inlet cavity cover plate 21 form a lower pump liquid inlet cavity A2;

[0083] The lower pump inlet cavity A2 contains the lower pump inlet valve 23 installed on the lower working cavity end cover 19;

[0084] The lower pump oil delivery channel 24 is formed on the lower working cavity end cover 19 and communicates with the lower pump working cavity B2 and the lower pump inlet cavity A2;

[0085] Exemplarily, the static sealing device is arranged between the lower pump inlet cavity cover plate 21 and the lower pump cylinder 18 to prevent oil leakage; and the static sealing device is arranged between the lower working cavity end cover 19 and the lower pump cylinder 18.

[0086] Exemplarily, the dynamic sealing device 8 is arranged between the lower pump light rod 107 of the motor system 10 and the lower pump cylinder 18 to realize sealing, the dynamic sealing device 8 realizes sealing through cooperation of the V-shaped sealing ring and the retainer, and the dustproof ring and the sand throwing ring are arranged on the outer side to realize multi-layer protection, so that oil and impurities are prevented from flowing into the motor system 10 and the service life is improved.

[0087] Exemplarily, the present application provides a control method of the double-pump system based on the screw rod driving submersible electric pump, which comprises the following steps:

[0088] The screw nut 103 is fixedly connected to the hollow motor rotor 104 through the spline, the motor rotor 104 drives the screw nut 103 to rotate reversely, thereby driving the screw rod 102 which is threadedly matched with the screw nut 103 to perform linear reciprocating motion in the axial direction; the upper part of the screw rod 102 is the upper pump light rod 101, the upper pump light rod 101 is connected with the upper pump plunger 7, and the periodic change of the volume of the motor integrated pump cylinder is realized through the up-down reciprocating motion of the upper pump plunger 7; when the screw rod 102 reversely rotates, the upper pump light rod 101 moves downward, thereby driving the upper pump plunger 7 to move downward, the volume of the upper working cavity B1 increases, and the oil enters the upper working cavity B1 through the upper pump inlet valve 3 under the action of the pressure difference, thereby completing the suction process of the upper pump system; at the same time, the lower pump light rod 107 moves downward, thereby driving the lower pump plunger 17 to move downward, the volume of the lower pump working cavity B2 decreases, the oil pressure increases, the oil is discharged through the hose 11, thereby completing the discharge process of the lower pump system; when the screw rod 102 rotates forward, the upper pump light rod 101 moves upward, thereby driving the upper pump plunger 7 to move upward, the volume of the upper working cavity B1 decreases, the oil pressure increases, the oil is discharged through the upper pump discharge valve 4, thereby completing the discharge process of the upper pump system; at the same time, the lower pump light rod 107 moves upward, thereby driving the lower pump plunger 17 to move upward, the oil enters the lower pump working cavity B2 through the lower pump inlet valve 23 under the action of the pressure difference, thereby completing the suction process of the lower pump.

[0089] The opening directions of the upper pump inlet valve 3, the upper pump discharge valve 4 and the lower pump discharge valve 12 are all toward the direction of the oil pipe 1, so as to ensure that the flow directions of the liquids are consistent.

[0090] The valve cores of the upper pump inlet valve 3, the upper pump discharge valve 4 and the lower pump discharge valve 12 are all spherical, so as to ensure that the flow of the liquids is not hindered.

[0091] The lead screw 102 adopts a ball screw or a threaded screw to adapt to different working requirements.

[0092] The example realizes the forward and reverse rotation of the lead screw 102 by connecting a servo motor or a bidirectional motor, and guarantees efficient and stable operation.

[0093] As can be seen from the above examples, in order to guarantee that the upper pump plunger 7 does not rotate during movement, the inner wall surface of the upper pump cylinder body 6 and the outer wall surface of the upper pump plunger 7 can be matched by a key groove, or a cylinder body and a plunger structure with a non-circular section are adopted. The motor system 10 is located in the middle of the double-pump system, the lead screw 102 is integrally machined with the upper and lower pump light rods 107, and the forward and reverse reciprocating motion of the lead screw 102 causes the light rod to reciprocate, thereby driving the plunger to reciprocate.

[0094] In order to improve the sealing performance, a static sealing device is arranged between the upper pump oil inlet cavity cover plate 2 and the upper pump cylinder body 6 to prevent oil leakage. A static sealing device is also arranged between the upper working cavity end cover 5 and the upper pump cylinder body 6 to prevent high-pressure oil from leaking into the liquid inlet cavity. A dynamic sealing device 8 is arranged between the light rod and the end cover to reduce wear and improve system life.

[0095] The double-pump system of the present application adopts a ball screw or a threaded screw, and the forward and reverse rotation of the lead screw 102 can be realized by a motor. The upper end of the hose 11 is threadedly connected with the upper pump oil inlet cavity cover plate 2, and the lower end is connected with the lower pump cylinder body 18 by a threaded joint and a high-pressure clamp to guarantee stable installation and facilitate maintenance. In addition, the hose 11 is fixed by a metal bracket and a clamp to avoid shaking of the hose 11, improve the stability of the system, and ensure reliable operation of the system under high-load working conditions. The material of the hose 11 is selected to be a polyurethane high-pressure hose to be suitable for high-sand oil wells and also suitable for deep wells.

[0096] In order to guarantee the sealing performance of the system, the lead screw 102 in the present application does not directly contact the plunger, but adopts a structure in which the lead screw connects the light rod, and the light rod connects the plunger. Compared with the structure in which the lead screw 102 directly connects the plunger, the sealing of the structure is easier to realize.

[0097] As can be seen from the above examples, the double-pump system based on the lead screw driven submersible electric pump proposed in the present application adopts lead screw driving technology to enable the pump to realize higher fluid delivery efficiency under the same power condition, and significantly improve the energy conversion efficiency.

[0098] The double-pump system based on the lead screw driven submersible electric pump proposed in the present application, since the lead screw 102 does not directly contact the plunger, but connects the light rod to drive the plunger, the sealing at the end cover is easier, and the service life of the lead screw 102 is improved, and the risk of failure caused by wear is reduced.

[0099] It can be understood that if the lead screw 102 directly drives the plunger movement, the seal needs to be arranged around the lead screw 102, and the lead screw 102 has a spiral groove and a rotating movement, which is difficult to seal efficiently. In the structure, the lead screw 102 drives the light rod, and then the light rod pushes the plunger to reciprocate, and the sealing of the light rod is easier than the sealing of the lead screw 102.

[0100] The double-pump system based on the lead screw driven submersible electric pump provided in the application has a double-pump parallel working structure, reduces the complexity of the pump body, is easy to install and maintain, and is especially suitable for use in difficult-to-access environments.

[0101] The double-pump system based on the lead screw driven submersible electric pump provided in the application adopts wear-resistant materials and an optimized structure design, can stably operate in a fluid containing sand and impurities, and improves the durability and reliability of the equipment.

[0102] The double-pump system based on the lead screw driven submersible electric pump provided in the application has a double-pump parallel working structure, reduces the complexity of the pump body, is easy to install and maintain, and is especially suitable for use in difficult-to-access environments.

[0103] In the above embodiments, the description of each embodiment focuses on different aspects, and the parts not described or recorded in a certain embodiment can be referred to the related description of other embodiments.

[0104] The following will theoretically analyze the positive effects of the application compared with the traditional submersible electric pump:

[0105] High energy utilization rate: the lead screw driving mode converts the rotating movement of the lead screw 102 into the linear movement of the light rod piston, and the transmission efficiency can reach 85%-95%, which is much higher than the transmission efficiency of the traditional submersible electric pump.

[0106] Low maintenance cost: the integrated lead screw 102 and light rod structure reduces part of the transmission components, the single maintenance time is reduced compared with the maintenance time of the traditional submersible electric pump, and the annual maintenance cost is expected to be reduced by 40%.

[0107] The above is only a preferred specific embodiment of the application, but the protection scope of the application is not limited thereto, and any modification, equivalent replacement and improvement within the technical range disclosed in the application and within the spirit and principles of the application should be covered within the protection scope of the application.

Claims

1. A dual pump system based on a screw drive electric submersible pump, characterized in that, The double-pump system comprises: The upper pump system is installed on the upper part of the motor system (10) and completes the oil suction and discharge processes by the driving power of the motor system (10); the upper pump system comprises an upper pump oil inlet cavity cover plate (2), an upper working cavity end cover (5), an upper pump cylinder body (6), an upper pump plunger (7) and an upper pump lower end cover (9); the upper pump oil inlet cavity cover plate (2) and the upper working cavity end cover (5) form a liquid discharge cavity (C); the liquid discharge cavity (C) and the upper pump oil inlet cavity cover plate (2) and the upper working cavity end cover (5) form an upper liquid inlet cavity (A1), the upper pump plunger (7) and the upper working cavity end cover (5) form an upper working cavity (B1), and the upper pump plunger (7) and the upper pump lower end cover (9) form a lower cavity; the upper pump plunger (7) is contained in the upper pump cylinder body (6); The motor system (10) completes the oil suction and discharge processes of the upper pump system and the lower pump system by the driving power provided by the motor system (10); the motor system (10) comprises an upper pump light rod (101), a lead screw (102), a lead screw nut (103) and a lower pump light rod (107); the lead screw (102) is integrally machined with the upper pump light rod (101) and the lower pump light rod (107), and the lead screw (102) and the lead screw nut (103) are threadedly engaged to realize linear reciprocating motion; The lower pump system is installed on the lower part of the motor system (10) and completes the oil discharge and suction processes by the driving power of the motor system (10) and in a reverse operation mode synchronously with the upper pump system; the lower pump system comprises a lower pump plunger (17) connected with the lower pump light rod (107), a lower pump cylinder body (18), a lower working cavity end cover (19) and a lower pump oil inlet cavity cover plate (21); the lower pump plunger (17) is freely slidably contained in the lower pump cylinder body (18); the lower pump cylinder body (18) and the lower working cavity end cover (19) are provided with a lower pump liquid discharge port (20); the lower pump plunger (17) and the lower working cavity end cover (19) form a lower pump working cavity (B2); and the lower working cavity end cover (19) and the lower pump oil inlet cavity cover plate (21) are provided with a lower pump liquid inlet port (22); The upper pump system further comprises an oil pipe (1), an upper pump liquid inlet valve (3), an upper pump liquid discharge valve (4) and a hose (11); The upper pump oil inlet cavity cover plate (2) is installed on the top of the upper pump cylinder body (6); The upper working cavity end cover (5) is installed on the upper end of the upper pump cylinder body (6) and is fixed with a one-way closed upper pump liquid inlet valve (3) in the upper liquid inlet cavity (A1); A one-way closed upper pump liquid discharge valve (4) is fixed in the liquid discharge cavity (C); The upper pump lower end cover (9) is installed on the bottom of the upper pump cylinder body (6); The upper pump oil inlet cavity cover plate (2) and the upper working cavity end cover (5) are provided with a liquid inlet hole (14) in communication with the hose (11); The hose (11) is used for connecting the lower pump liquid discharge port (20) of the lower pump system and the oil pipe (1). The upper pump light pole (101) of the motor system (10) and the upper pump lower end cover (9) are sealed by a dynamic sealing device (8), the dynamic sealing device (8) is sealed by cooperating with a V-shaped sealing ring and a check ring, and the outer side of the dynamic sealing device (8) is provided with a dustproof ring and a sand throwing ring multilayer protection.

2. The dual pump system based on a nutating electric submersible pump of claim 1, characterized in that, The upper working chamber end cover (5) is provided with an upper liquid inlet channel (15) for connecting the upper liquid inlet chamber (A1) and the upper working chamber (B1); and a liquid discharge channel (16) for connecting the upper working chamber (B1) and the liquid discharge chamber (C).

3. The dual pump system based on a nutating electric submersible pump of claim 2, characterized in that, The upper pump liquid discharge valve (4) is installed at the upper portion of the liquid discharge channel (16); and the liquid discharge channel (16) is arranged in a semicircular ring shape.

4. The dual pump system based on a nutating electric submersible pump of claim 1, characterized in that, Static sealing devices are arranged between the upper pump oil inlet chamber cover plate (2) and the upper pump cylinder body (6), and between the upper working chamber end cover (5) and the upper pump cylinder body (6); The upper portion of the hose (11) is provided with an upper through hole (13); the oil pipe (1) is internally provided with a lower pump liquid discharge valve (12) of a lower pump system; the upper through hole (13) is communicated with the oil pipe (1) through the lower pump liquid discharge valve (12); The upper end of the hose (11) is threadedly connected with the upper pump oil inlet chamber cover plate (2), the hose (11) is fixed by a metal support and a clamp, and a limit detection device for monitoring the vibration state of the hose (11) in real time is arranged in the middle of the hose (11).

5. The dual pump system based on a nutating electric submersible pump of claim 1, characterized in that, The motor system (10) further comprises a motor rotor (104), a motor stator (105) and a motor shell (106); the motor stator (105) is installed on the motor shell (106); the screw nut (103) is fixedly connected with the motor rotor (104) through a spline; and the screw nut (103) drives the screw rod (102) to make reciprocating motion.

6. The dual pump system based on a nutating electric submersible pump of claim 5, characterized in that, The lower working chamber end cover (19) and the lower pump oil inlet chamber cover plate (21) form a lower pump liquid inlet chamber (A2); The lower pump liquid inlet chamber (A2) contains a lower pump liquid inlet valve (23) installed on the lower working chamber end cover (19); The lower working chamber end cover (19) is provided with a lower pump oil liquid conveying channel (24) for connecting the lower pump working chamber (B2) and the lower pump liquid inlet chamber (A2).

7. The dual pump system based on a nutating electric submersible pump of claim 6, characterized in that, Static sealing devices are arranged between the lower pump oil inlet chamber cover plate (21) and the lower pump cylinder body (18), and between the lower working chamber end cover (19) and the lower pump cylinder body (18); The lower pump light pole (107) of the motor system (10) and the lower pump cylinder body (18) are sealed by a dynamic sealing device (8), the dynamic sealing device (8) is sealed by cooperating with a V-shaped sealing ring and a check ring, and the outer side is provided with a dustproof ring and a sand throwing ring multilayer protection.

8. A control method of a dual pump system based on a wire-rod driving electric submersible pump, characterized by, The control for the double-pump system based on the screw rod driven submersible electric pump according to any one of claims 5-7 comprises: The screw nut (103) is fixedly connected with the hollow motor rotor (104) through the spline, the motor rotor (104) drives the screw nut (103) to rotate forward and reversely, thereby driving the screw rod (102) threaded with the screw nut (102) to move linearly in the axial direction; the upper pump light rod (101) is connected with the upper pump plunger (7), and the up-and-down reciprocating movement of the upper pump plunger (7) realizes the periodic change of the volume of the motor integrated pump cylinder; when the screw rod (102) reverses, the upper pump light rod (101) moves downward, driving the upper pump plunger (7) to move downward, the volume of the upper working cavity (B1) increases, and under the action of the pressure difference, the oil enters the upper working cavity (B1) through the upper pump inlet valve (3), completing the suction process of the upper pump system, and at the same time, the lower pump light rod (107) moves downward, driving the lower pump plunger (17) to move downward, the volume of the lower pump working cavity (B2) decreases, the oil pressure rises, and the oil is discharged through the hose (11), completing the discharge process of the lower pump system; When the screw rod (102) rotates forward, the upper pump light rod (101) moves upward, driving the upper pump plunger (7) to move upward, the volume of the upper working cavity (B1) decreases, the oil pressure rises, and the oil is discharged through the upper pump discharge valve (4), completing the discharge process of the upper pump system, and at the same time, the lower pump light rod (107) moves upward, driving the lower pump plunger (17) to move upward, under the action of the pressure difference, the oil enters the lower pump working cavity (B2) through the lower pump inlet valve (23), completing the suction process of the lower pump system; The upper pump system and the lower pump system are in the continuous suction process and the discharge process, a limiting detection device is arranged in the middle of the hose (11), which is used for monitoring the vibration state of the hose (11) in real time; when the shaking amplitude or frequency exceeds the set threshold value, the control system issues an alarm or executes a speed reduction or shutdown operation.

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