Motor-driven safety relief valve for shale oil exploitation fracturing

Abstract

The invention discloses a motor-driven safety relief valve for shale oil exploitation fracturing. Comprising a servo motor, a speed reducer fixedly arranged on the lower portion of the servo motor, a speed reducer output shaft fixedly arranged on the lower portion of the speed reducer, a driving sleeve arranged outside the speed reducer output shaft in a sleeving mode, a driving nut fixedly arranged at the lower end of the driving sleeve and rotating coaxially with the driving sleeve, and a valve body provided with a valve cavity. A valve rod in threaded connection with the driving nut is movably arranged in the valve rod sleeve and the upper valve seat, a pressure relief valve element matched with the upper valve seat is arranged on the lower portion of the valve rod, a valve cavity annular groove is formed in the periphery of the valve cavity, a pressure sensor and a valve body liquid inlet are arranged on the two sides of the valve cavity annular groove respectively, and a valve rod sleeve cavity is formed in the lower portion of the valve rod sleeve. The valve rod sleeve cavity communicates with the valve cavity annular groove through a plurality of valve rod sleeve cavity liquid inlets formed in the radial direction, and a valve body liquid outlet is formed in the bottom of the valve cavity. Liquid pressure is collected through the pressure sensor, the servo motor is controlled to drive the valve rod to move, and active control over opening and closing of the safety relief valve is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of shale oil exploitation equipment, and more specifically, to a motor-driven safety pressure relief valve for shale oil exploitation fracturing. Background Art

[0002] During shale oil fracturing operations, the working pressure of the fracturing fluid is as high as 120 MPa. Therefore, a safety pressure relief valve must be installed on the fracturing fluid delivery pipeline to prevent the working pressure of the fracturing fluid from exceeding the set maximum pressure and causing production safety accidents. Therefore, the safety pressure relief valve is one of the core equipment in shale gas fracturing operations.

[0003] There are two structures of safety pressure relief valves currently used in shale oil extraction fracturing, one is a safety pressure relief valve based on spring preload, and the other is a safety pressure relief valve based on safety pin; when the safety pressure relief valve based on spring preload is working, once the fracturing fluid pressure is higher than the set safety pressure, the safety pressure relief valve overcomes the spring preload and automatically works to relieve pressure, and can recover by itself after pressure relief, which does not affect the continuity of shale oil extraction fracturing production, but the safety pressure relief valve based on spring preload has a small pressure relief flow and a slow pressure relief speed when working, so the response speed to the safety pressure is slow; when the safety pressure relief valve based on safety pin is working, when the fracturing fluid pressure is higher than the set When the safety pressure is reached, the safety pin will be cut off to release the pressure. The pressure relief flow is large and the pressure relief speed is fast, so the response speed to the safety pressure is fast. However, once the safety pin is cut off, the safety relief valve cannot recover by itself, thus affecting the continuity of shale oil fracturing production. In addition, the safety relief valve based on the safety pin has deviations in the material properties of the safety pin or deviations in the parameters during the heat treatment process, which will cause differences in the consistency of the strength of the safety pin. This difference causes the pressure relief valve to deviate from the set safety pressure. When the pressure relief valve is higher than the set safety pressure, it is easy to cause pipeline rupture or other equipment leakage, thereby causing production safety accidents. Due to the above-mentioned defects of the existing safety relief valves for shale oil fracturing, they need to be improved. Summary of the invention

[0004] The purpose of the present invention is to provide a motor-driven safety pressure relief valve for shale oil extraction and fracturing, which collects liquid pressure through a pressure sensor, controls the servo motor to drive the valve stem movement, and realizes active control of the safety pressure relief valve switch.

[0005] The technical solution adopted by the present invention to solve this technical problem is: to provide a motor-driven safety pressure relief valve for shale oil extraction and fracturing, comprising: a pressure relief valve, a drive connection assembly, and a drive assembly connected to the pressure relief valve through the drive connection assembly; The drive assembly includes a servo motor, a reducer fixedly mounted at the lower part of the servo motor and a reducer output shaft fixedly mounted at the lower part of the reducer, the drive connection assembly includes a drive sleeve mounted outside the reducer output shaft and a drive nut fixedly mounted at the lower end of the drive sleeve and coaxially rotating with the drive sleeve, the pressure relief valve includes a valve body provided with a valve cavity, a valve stem sleeve, an upper valve seat and a lower valve seat are sequentially arranged in the valve cavity from top to bottom, a valve stem which is movably arranged in the valve stem sleeve, the upper valve seat and the lower valve seat and is connected to the drive nut by a thread, a pressure relief valve core which cooperates with the upper valve seat is provided at the lower part of the valve stem, the pressure relief valve core and the valve stem are an integral structure or a split structure, a valve cavity annular groove is provided at the outer periphery of the valve cavity, pressure sensors and a valve body liquid inlet are respectively provided on the two side walls of the valve cavity annular groove, a valve stem sleeve cavity is provided at the lower part of the valve stem sleeve, the valve stem sleeve cavity is connected with the valve cavity annular groove through a plurality of valve stem sleeve cavity liquid inlets arranged radially, and a valve body liquid outlet is provided at the bottom of the valve cavity.

[0006] Preferably, in the motor-driven safety pressure relief valve for shale oil extraction and fracturing, the drive nut and the drive sleeve are both cylindrical, a plurality of drive nut bosses are evenly arranged on the upper end of the drive nut, a bearing positioning shoulder is arranged on the outer periphery of the lower part of the drive nut, a plurality of drive sleeve key grooves are arranged on the inner peripheral surface of the drive sleeve, and a plurality of drive sleeve end grooves are arranged at the position of the drive nut boss at the lower end of the drive sleeve; The end groove of the drive sleeve matches the boss of the drive nut; A plurality of flat keys are arranged on the output shaft of the reducer at positions corresponding to the keyways of the drive sleeve, and the flat keys match the keyways of the drive sleeve.

[0007] Preferably, in the motor-driven safety pressure relief valve for shale oil extraction and fracturing, the drive connection assembly further comprises a connecting flange sleeve and a thrust bearing; The connecting flange sleeve is arranged outside the driving sleeve and the driving nut. The upper and lower ends of the connecting flange sleeve are fixedly connected to the lower end of the reducer and the upper end of the pressure relief valve respectively. Several thrust bearings are respectively arranged on the upper end face and the lower end face of the bearing positioning shoulder. The driving nut is rotatably connected to the connecting flange sleeve through the thrust bearing.

[0008] Preferably, in the motor-driven safety pressure relief valve for shale oil extraction and fracturing, the upper valve seat is annular, with an upper valve seat cavity in the middle, the upper part of the upper valve seat cavity is the valve seat working surface, the upper part of the pressure relief valve core is the pressure relief valve core working surface, the valve seat working surface and the pressure relief valve core working surface are both conical surfaces, and the pressure relief valve core and the upper valve seat are matched through the conical surface.

[0009] Preferably, in the motor-driven safety pressure relief valve for shale oil extraction and fracturing, the lower valve seat comprises a circular plate-shaped lower valve seat body and an inverted cone-shaped valve stem lower support seat arranged at the lower part of the lower valve seat body, a countersunk hole is provided in the middle of the upper part of the lower valve seat body, a plurality of through liquid holes are evenly distributed at the bottom of the countersunk hole, a valve stem support hole is provided in the middle of the valve stem lower support seat, and a through hole is provided at the bottom of the valve stem support hole.

[0010] Preferably, in the motor-driven safety pressure relief valve for shale oil extraction and fracturing, the upper end of the valve stem is an upper screw head, the upper screw head is threadedly connected to the drive nut, and the lower end of the pressure relief valve core is a lower support head, and the lower support head is arranged in the valve stem support hole.

[0011] Preferably, the motor-driven safety pressure relief valve for shale oil extraction and fracturing, the pressure relief valve also includes an upper end cover, the upper end cover is arranged between the valve body and the drive connection assembly, the inner circumferential surface of the upper end cover is provided with a guide groove, the upper part of the valve stem is fixedly provided with a guide key, and the guide key cooperates with the guide groove.

[0012] Preferably, in the motor-driven safety pressure relief valve for shale oil extraction and fracturing, the cross-sectional size of the pressure relief valve core is larger than the cross-sectional size of the valve stem on the upper part of the pressure relief valve core.

[0013] Preferably, in the motor-driven safety pressure relief valve for shale oil extraction and fracturing, the valve stem sleeve cavity liquid inlet opening is arranged on the valve stem sleeve cavity with an upward tilt.

[0014] Preferably, in the motor-driven safety pressure relief valve for shale oil extraction and fracturing, a sensor mounting hole is provided on one side wall of the valve chamber ring groove, and the pressure sensor is fixedly arranged in the sensor mounting hole.

[0015] The present invention includes at least the following beneficial effects: a motor-driven safety pressure relief valve for shale oil extraction and fracturing disclosed in the present invention is provided with a driving component and a pressure sensor, wherein the liquid pressure in the pressure relief valve is collected by the pressure sensor to control the action of the driving component; the action of the driving component drives the action of the pressure relief valve to actively control the opening or closing of the pressure relief valve; the safety pressure relief valve has the advantages of accurate pressure control, self-recovery and fast response speed, thus solving the defects of the existing safety pressure relief valve for shale oil extraction and fracturing and ensuring the continuity and safety of shale oil extraction and fracturing production.

[0016] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the structure of a motor-driven safety pressure relief valve for shale oil extraction and fracturing; Figure 2 It is a schematic diagram of the structure of a driving component in a motor-driven safety pressure relief valve for shale oil extraction and fracturing; Figure 3 This is a schematic diagram of the structure of a valve body in a motor-driven safety pressure relief valve for shale oil extraction and fracturing; Figure 4This is a schematic diagram of the structure of a valve stem sleeve in a motor-driven safety pressure relief valve for shale oil extraction and fracturing; Figure 5 This is a schematic diagram of the structure of an upper valve seat in a motor-driven safety pressure relief valve for shale oil extraction and fracturing; Figure 6 It is a schematic diagram of the structure of the lower valve seat in a motor-driven safety pressure relief valve for shale oil extraction and fracturing; Figure 7 This is a schematic diagram of the structure of a valve stem in a motor-driven safety pressure relief valve for shale oil extraction and fracturing; Figure 8 It is a schematic diagram of the structure of a driving component in a motor-driven safety pressure relief valve for shale oil extraction and fracturing; Fig. 9 It is a schematic diagram of the structure of a driving connection assembly in a motor-driven safety pressure relief valve for shale oil extraction and fracturing; Fig.10 It is an axonometric view of a drive sleeve in a motor-driven safety pressure relief valve for shale oil extraction and fracturing; Fig.11 This is an axonometric view of a drive nut in a motor-driven safety relief valve for shale oil extraction and fracturing; Explanation of reference numerals: 1. pressure relief valve; 1.1. upper end cover; 1.2. valve body; 1.2.1. valve cavity; 1.2.2. valve cavity ring groove; 1.2.3. valve body liquid inlet; 1.2.4. sensor mounting hole; 1.2.5. valve body liquid outlet; 1.3. valve stem sleeve; 1.3.1. valve stem sleeve cavity; 1.3.2. valve stem sleeve cavity liquid inlet; 1.4. upper valve seat; 1.4.1. valve seat working surface; 1.4.2. upper valve seat cavity; 1.5. lower valve seat; 1.5.1. lower valve seat body; 1.5.2. valve stem lower support seat; 1.5.3. liquid hole; 1.5.4. Stem support hole; 1.6, valve stem; 1.6.1, upper screw head; 1.6.2, pressure relief valve core; 1.6.3, guide key; 1.6.4, lower support head; 1.7, pressure sensor; 2, drive assembly; 2.1, servo motor; 2.2, reducer; 2.2.1, reducer output shaft; 3, drive connection assembly; 3.1, connecting flange sleeve; 3.2, drive sleeve; 3.2.1, drive sleeve keyway; 3.2.2, drive sleeve end groove; 3.3, drive nut; 3.3.1, drive nut boss; 3.3.2, bearing locating shoulder; 3.4, thrust bearing. DETAILED DESCRIPTION

[0018] The present invention is described in detail and completely below in conjunction with the accompanying drawings. A person of ordinary skill in the art will be able to implement the present invention based on these descriptions. Before describing the present invention in conjunction with the accompanying drawings, it should be particularly pointed out that the technical solutions and technical features provided in each part of the present invention, including the following description, can be combined with each other without conflict.

[0019] In addition, the embodiments of the present invention involved in the following description are generally only a part of the embodiments of the present invention, rather than all the embodiments. Therefore, based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0020] The present invention is further described in detail below with reference to the accompanying drawings and embodiments, and its specific implementation process is as follows: Figure 1-11 As shown, the present invention provides a motor-driven safety pressure relief valve for shale oil extraction and fracturing, comprising: a pressure relief valve 1, a drive connection component 3 and a drive component 2 that is transmission-connected to the pressure relief valve 1 through the drive connection component 3; the drive component 2 drives the pressure relief valve 1 to realize an opening or closing action.

[0021] The driving assembly 2 comprises a servo motor 2.1, a reducer 2.2 fixedly mounted below the servo motor 2.1 and a reducer output shaft 2.2.1 fixedly mounted below the reducer 2.2. The rotation of the servo motor 2.1 is decelerated by the reducer 2.2 and then outputted through the reducer output shaft 2.2.1. The servo motor operates in a closed-loop feedback control mode.

[0022] The drive connection assembly 3 includes a drive sleeve 3.2 sleeved on the output shaft 2.2.1 of the reducer and a drive nut 3.3 fixed at the lower end of the drive sleeve 3.2 and coaxially rotating with the drive sleeve 3.2. The pressure relief valve 1 includes a valve body 1.2 provided with a valve cavity 1.2.1, in which a valve stem sleeve 1.3, an upper valve seat 1.4 and a lower valve seat 1.5 are arranged from top to bottom in the valve cavity 1.2.1. A valve stem 1.6 threadedly connected to the drive nut 3.3 is movably arranged in the valve stem sleeve 1.3, the upper valve seat 1.4 and the lower valve seat 1.5. When the output shaft 2.2.1 of the reducer rotates, the drive sleeve 3.2 drives the drive nut 3.3 to rotate, and the drive nut 3.3 rotates to drive the valve stem 1.6 to move upward or downward.

[0023] A pressure relief valve core 1.6.2 is provided at the lower part of the valve stem 1.6 to cooperate with the upper valve seat 1.4. In one embodiment, the pressure relief valve core 1.6.2 and the valve stem 1.6 are an integral structure, and in another embodiment, the pressure relief valve core 1.6.2 and the valve stem 1.6 are a separate structure. In the latter embodiment, the pressure relief valve core 1.6.2 is annular, and is provided with an outer cylindrical surface of a lower support head 1.6.4, and is fixedly connected to the valve stem 1.6 through a safety pin; A valve cavity annular groove 1.2.2 is provided on the periphery of the valve cavity 1.2.1, and pressure sensors 1.7 and valve body liquid inlet 1.2.3 are provided on both side walls of the valve cavity annular groove 1.2.2, respectively. A valve stem sleeve cavity 1.3.1 is provided at the lower part of the valve stem sleeve 1.3, and the valve stem sleeve cavity 1.3.1 is communicated with the valve cavity annular groove 1.2.2 through a plurality of valve stem sleeve cavity liquid inlets 1.3.2 arranged radially, and a valve body liquid outlet 1.2.5 is provided at the bottom of the valve cavity 1.2.1. In this embodiment, a preferred implementation scheme is that the valve stem sleeve 1.3 is cylindrical, with a through hole in the middle, two sealing ring grooves are provided at the upper part of the through hole, a valve stem sleeve cavity 1.3.1 is provided at the lower part of the through hole, and four valve stem sleeve cavity liquid inlets 1.3.2 are evenly distributed on the side walls of the valve stem sleeve cavity 1.3.1.

[0024] In the above technical solution, when the motor-driven safety pressure relief valve for shale oil exploitation fracturing is working, the fracturing fluid delivery pipeline is connected to the valve body liquid inlet 1.2.3 of the safety pressure relief valve through the bypass pipeline, the valve body liquid outlet 1.2.5 of the safety pressure relief valve is connected to the fracturing fluid storage tank through the return liquid pipeline, and the pressure sensor 1.7 and the servo motor 2.1 are electrically connected to the control system of the shale oil exploitation fracturing system. When the ultra-high pressure liquid enters the valve cavity annular groove 1.2.2 from the valve body liquid inlet 1.2.3, the pressure sensor 1.7 detects the ultra-high pressure liquid pressure in the valve cavity annular groove 1.2.2 and transmits it to the control system. When the control system determines that the ultra-high pressure liquid pressure in the valve cavity annular groove 1.2.2 exceeds the set working pressure, the servo motor 2.1 is controlled to work and the pressure relief valve 1 is opened for pressure relief; when the control system determines that the ultra-high pressure liquid pressure in the valve cavity annular groove 1.2.2 is less than the set working pressure, the servo motor 2.1 is controlled to work and the pressure relief valve 1 is closed, thereby realizing the active opening or closing of the pressure relief valve 1. Since the safety pressure relief valve adopts the pressure sensor 1.7 to collect the liquid pressure in the pressure relief valve 1, it has the advantage of accurate pressure control; since the servo motor 2.1 is used to drive the pressure relief valve 1 to act in both directions, it has the advantages of self-recovery after pressure relief and fast response speed; the safety pressure relief valve solves many defects of the existing safety pressure relief valves for shale oil extraction and fracturing, and ensures the continuity and safety of shale oil extraction and fracturing production.

[0025] Furthermore, in the motor-driven safety pressure relief valve for shale oil extraction and fracturing, the drive nut 3.3 and the drive sleeve 1.3 are both cylindrical, and the drive nut 3.3 and the drive sleeve 1.3 are both rotatably arranged in the flange cavity of the connecting flange sleeve 3.1, and the upper end surface of the drive nut 3.3 is evenly distributed with a plurality of drive nut bosses 3.3.1, the lower outer periphery of the drive nut 3.3 is provided with a bearing positioning shoulder 3.3.2, the inner circumferential surface of the drive nut 3.3 is provided with a T-type thread, the inner circumferential surface of the drive sleeve 1.3 is provided with a plurality of drive sleeve key grooves 3.2.1, and the lower end surface of the drive sleeve 1.3 is provided with a plurality of drive sleeve end grooves 3.2.2 at positions corresponding to the drive nut bosses 3.3.1; in the present embodiment, a preferred implementation scheme is that the number of the drive sleeve end grooves 3.2.2 and the number of the drive nut bosses 3.3.1 are both four.

[0026] The drive sleeve end groove 3.2.2 matches the drive nut boss 3.3.1; The reducer output shaft 2.2.1 is provided with a plurality of flat keys at positions corresponding to the drive sleeve key slots 3.2.1, and the flat keys match the drive sleeve key slots 3.2.1. The reducer output shaft 2.2.1 is inserted into the inner hole of the drive sleeve 3.2, and the reducer output shaft 2.2.1 and the drive sleeve 3.2 are connected by flat keys.

[0027] Furthermore, in the motor-driven safety pressure relief valve for shale oil extraction and fracturing, the drive connection assembly 3 further includes a connecting flange sleeve 3.1 and a thrust bearing 3.4; The connecting flange sleeve 3.1 is sleeved outside the driving sleeve 3.2 and the driving nut 3.3. The upper and lower ends of the connecting flange sleeve 3.1 are fixedly connected to the lower end of the reducer 2.2 and the upper end of the pressure relief valve 1 respectively. A plurality of thrust bearings 3.4 are respectively arranged on the upper and lower end surfaces of the bearing positioning shoulder 3.3.2. The driving nut 3.3 is rotatably connected to the connecting flange sleeve 3.1 through the thrust bearing 3.4.

[0028] In the above technical solution, the connecting flange sleeve 3.1 is provided with connecting flanges at both ends, the upper connecting flange is fixedly connected to the lower end face of the reducer 2.2, the lower connecting flange is fixedly connected to the upper end of the pressure relief valve 1, a flange cavity is provided in the middle of the connecting flange sleeve 3.1, and a step ring is provided near the lower part of the flange cavity. The drive sleeve end groove 3.2.2 and the drive nut boss 3.3.1 are rotatably arranged in the flange cavity of the connecting flange sleeve 3.1, and two sets of thrust bearings 3.4 are arranged, one set is arranged between the upper end face of the bearing positioning shoulder 3.3.2 of the drive nut 3.3 and the lower end face of the step ring of the connecting flange sleeve 3.1, and the other set is arranged between the lower end face of the bearing positioning shoulder 3.3.2 of the drive nut 3.3 and the upper end face of the pressure relief valve 1.

[0029] Furthermore, in the motor-driven safety pressure relief valve for shale oil extraction and fracturing, the upper valve seat 1.4 is annular, with an upper valve seat cavity 1.4.2 in the middle, the upper part of the upper valve seat cavity 1.4.2 is the valve seat working surface 1.4.1, the upper part of the pressure relief valve core 1.6.2 is the pressure relief valve core working surface, the valve seat working surface 1.4.1 and the pressure relief valve core working surface are both conical surfaces, the pressure relief valve core 1.6.2 and the upper valve seat 1.4 are matched through the conical surface, when the pressure relief valve 1 is closed, the conical surface matching has the advantage of good sealing, thereby preventing the pressure relief valve 1 from leaking in the non-pressure relief state.

[0030] Furthermore, in the motor-driven safety pressure relief valve for shale oil extraction and fracturing, the lower valve seat 1.5 comprises a circular plate-shaped lower valve seat body 1.5.1 and an inverted cone-shaped valve stem lower support seat 1.5.2 arranged at the lower part of the lower valve seat body 1.5.1, a countersunk hole is provided in the middle of the upper part of the lower valve seat body 1.5.1, and a plurality of through liquid holes 1.5.3 are evenly distributed at the bottom of the countersunk hole, a valve stem support hole 1.5.4 is provided in the middle of the valve stem lower support seat 1.5.2, and a through hole is provided at the bottom of the valve stem support hole 1.5.4 to prevent air entrapment when the valve stem 1.6 moves.

[0031] Furthermore, in the motor-driven safety pressure relief valve for shale oil extraction and fracturing, the upper end of the valve stem 1.6 is an upper screw head 1.6.1, and the upper screw head 1.6.1 is threadedly connected to the drive nut 3.3, and the lower end of the pressure relief valve core 1.6.2 is a lower support head 1.6.4, and the lower support head 1.6.4 is arranged in the valve stem support hole 1.5.4.

[0032] In the above technical solution, the valve stem sleeve 1.3 and the valve stem support hole 1.5.4 of the lower valve seat 1.5 form a double sliding support for the valve stem 1.6. When the pressure relief valve 1 is relieving pressure, the ultra-high pressure liquid has an extremely high flow rate in the pressure relief valve 1. The valve stem 1.6 is very likely to vibrate under the impact of the high-speed flow of the ultra-high pressure liquid. When the valve stem 1.6 is supported at both ends, the vibration of the valve stem when the liquid flows through the pressure relief valve can be greatly reduced, thereby preventing the valve stem from breaking due to vibration.

[0033] Furthermore, the motor-driven safety pressure relief valve for shale oil extraction and fracturing, the pressure relief valve 1 also includes an upper end cover 1.1, the upper end cover 1.1 is arranged between the valve body 1.2 and the drive connection assembly 3, the lower end surface of the upper end cover 1.1 abuts against the upper end surface of the valve stem sleeve 1.3, the inner circumferential surface of the upper end cover 1.1 is provided with a guide groove, the upper part of the valve stem 1.6 is fixedly provided with a guide key 1.6.3, the guide key 1.6.3 cooperates with the guide groove to prevent the valve stem 1.6 from rotating.

[0034] Furthermore, in the motor-driven safety pressure relief valve for shale oil extraction and fracturing, the cross-sectional size of the pressure relief valve core 1.6.2 is larger than the cross-sectional size of the valve stem 1.6 on the upper part of the pressure relief valve core 1.6.2. In the present embodiment, a preferred implementation scheme is that the cross-sectional size of the pressure relief valve core 1.6.2 is slightly larger than the cross-sectional size of the valve stem 1.6 on the upper part of the pressure relief valve core 1.6.2, that is, the valve stem 1.6 is always subjected to tension during operation, and the tension is not too large. When ultra-high pressure liquid enters the valve stem sleeve cavity 1.3.1, a downward force is applied to the valve stem 1.6 through the pressure relief valve core 1.6.2, so that the force exerted on the valve stem 1.6 in the ultra-high pressure liquid is the same as the opening direction of the valve stem 1.6, thereby ensuring the reliability of the opening of the pressure relief valve 1. At the same time, even if the valve stem 1.6 breaks, the pressure relief valve 1 is in an open state under the action of the ultra-high pressure liquid, thereby ensuring the safety of the shale gas extraction and fracturing operation.

[0035] Furthermore, in the motor-driven safety pressure relief valve for shale oil extraction and fracturing, the valve stem sleeve cavity liquid inlet 1.3.2 is inclined upwardly and arranged on the valve stem sleeve cavity 1.3.1 to reduce the speed at which ultra-high pressure liquid enters the valve stem sleeve cavity 1.3.1.

[0036] Furthermore, in the motor-driven safety pressure relief valve for shale oil extraction and fracturing, a sensor mounting hole 1.2.4 is provided on one side wall of the valve chamber ring groove 1.2.2, and the pressure sensor 1.7 is fixedly arranged in the sensor mounting hole 1.2.4.

[0037] During shale oil extraction and fracturing operations, the ultra-high pressure liquid in the fracturing fluid delivery pipeline enters the valve cavity annular groove 1.2.2 of the valve body 1.2 through the bypass pipeline, and then enters the valve stem sleeve cavity 1.3.1 through the valve stem sleeve cavity liquid inlet 1.3.2 of the valve stem sleeve 1.3; the pressure sensor 1.7 detects the ultra-high pressure liquid pressure in the valve cavity annular groove 1.2.2 in real time. When the pressure sensor 1.7 detects that the ultra-high pressure liquid pressure exceeds the system set value, the control system controls the servo motor 2.1 to rotate counterclockwise, and after being decelerated by the reducer 2.2, it rotates counterclockwise from the reducer output shaft 2.2.1; the reducer output shaft 2.2.1 drives the drive sleeve 3.2 to rotate counterclockwise, and the drive sleeve 3.2 drives the drive nut 3.3 to rotate counterclockwise, and the drive nut 3.3 rotates counterclockwise. The clockwise rotation drives the upper screw head 1.6.1 to move downward, thereby causing the valve stem 1.6 to move downward as a whole, and the pressure relief valve core 1.6.2 of the valve stem 1.6 to disengage from the valve seat working surface 1.4.1 of the upper valve seat 1.4, and the ultra-high pressure liquid in the pressure relief valve 1 is discharged from the valve body outlet 1.2.5, causing the pressure in the fracturing fluid delivery pipeline to drop; when the pressure sensor 1.7 detects in real time that the pressure value of the ultra-high pressure liquid in the valve cavity ring groove 1.2.2 is less than the set system setting value, the control system controls the servo motor 2.1 to rotate clockwise, driving the valve stem 1.6 to move upward as a whole, and the pressure relief valve core 1.6.2 of the valve stem 1.6 re-contacts the valve seat working surface 1.4.1 of the upper valve seat 1.4 to shut off the pressure relief valve 1, causing the pressure in the fracturing fluid delivery pipeline to rise.

[0038] When the valve stem 1.6 breaks during operation, the pressure relief valve 1 is also in an open state under the action of the ultra-high pressure liquid, thereby ensuring the safety of rock gas extraction and fracturing operations.

[0039] In the technical solution using a separate structure of the pressure relief valve core 1.6.2 and the valve stem 1.6, when the pressure of the ultra-high pressure liquid in the valve chamber ring groove 1.2.2 is greater than the system set pressure and exceeds a certain range, and the servo motor 2.1 still does not move, the pressure relief valve core 1.6.2 cuts off the safety pin under the action of the ultra-high pressure liquid pressure and slides downward to open the pressure relief valve 1; this technical solution enables the motor-driven safety pressure relief valve for shale oil extraction and fracturing to have a self-safety protection function, ensuring that the safety of shale gas extraction and fracturing operations can still be ensured when a control system or servo motor 2.1 fails.

[0040] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and the embodiments shown and described herein.

Claims

1. A motor-driven safety pressure relief valve for shale oil extraction and fracturing, characterized in that: include: A pressure relief valve, a drive connection assembly, and a drive assembly drivingly connected to the pressure relief valve via the drive connection assembly; The drive assembly includes a servo motor, a reducer fixedly mounted at the lower part of the servo motor and a reducer output shaft fixedly mounted at the lower part of the reducer, the drive connection assembly includes a drive sleeve mounted outside the reducer output shaft and a drive nut fixedly mounted at the lower end of the drive sleeve and coaxially rotating with the drive sleeve, the pressure relief valve includes a valve body provided with a valve cavity, a valve stem sleeve, an upper valve seat and a lower valve seat are sequentially arranged in the valve cavity from top to bottom, a valve stem which is movably arranged in the valve stem sleeve, the upper valve seat and the lower valve seat and is connected to the drive nut by a thread, a pressure relief valve core which cooperates with the upper valve seat is provided at the lower part of the valve stem, the pressure relief valve core and the valve stem are an integral structure or a split structure, a valve cavity annular groove is provided at the outer periphery of the valve cavity, pressure sensors and a valve body liquid inlet are respectively provided on the two side walls of the valve cavity annular groove, a valve stem sleeve cavity is provided at the lower part of the valve stem sleeve, the valve stem sleeve cavity is connected with the valve cavity annular groove through a plurality of valve stem sleeve cavity liquid inlets arranged radially, and a valve body liquid outlet is provided at the bottom of the valve cavity.

2. The motor-driven safety pressure relief valve for shale oil extraction and fracturing as claimed in claim 1, characterized in that: The drive nut and the drive sleeve are both cylindrical, the upper end of the drive nut is evenly provided with a plurality of drive nut bosses, the outer periphery of the lower part of the drive nut is provided with a bearing positioning shoulder, the inner peripheral surface of the drive sleeve is provided with a plurality of drive sleeve key grooves, and the lower end of the drive sleeve is provided with a plurality of drive sleeve end grooves at positions corresponding to the drive nut bosses; The end groove of the drive sleeve matches the boss of the drive nut; A plurality of flat keys are arranged on the output shaft of the reducer at positions corresponding to the keyways of the drive sleeve, and the flat keys match the keyways of the drive sleeve.

3. The motor-driven safety pressure relief valve for shale oil extraction and fracturing as claimed in claim 2, characterized in that: The drive connection assembly also includes a connecting flange sleeve and a thrust bearing; The connecting flange sleeve is arranged outside the driving sleeve and the driving nut. The upper and lower ends of the connecting flange sleeve are fixedly connected to the lower end of the reducer and the upper end of the pressure relief valve respectively. Several thrust bearings are respectively arranged on the upper end face and the lower end face of the bearing positioning shoulder. The driving nut is rotatably connected to the connecting flange sleeve through the thrust bearing.

4. The motor-driven safety pressure relief valve for shale oil extraction and fracturing as claimed in claim 1, characterized in that: The upper valve seat is annular, with an upper valve seat cavity in the middle, the upper part of the upper valve seat cavity is the valve seat working surface, the upper part of the pressure relief valve core is the pressure relief valve core working surface, the valve seat working surface and the pressure relief valve core working surface are both conical surfaces, and the pressure relief valve core and the upper valve seat are matched through the conical surface.

5. The motor-driven safety pressure relief valve for shale oil extraction and fracturing as claimed in claim 1, characterized in that: The lower valve seat includes a circular plate-shaped lower valve seat body and an inverted cone-shaped valve stem lower support seat arranged at the lower part of the lower valve seat body. A countersunk hole is provided in the middle of the upper part of the lower valve seat body, and a plurality of liquid holes are evenly distributed at the bottom of the countersunk hole. A valve stem support hole is provided in the middle of the valve stem lower support seat, and a through hole is provided at the bottom of the valve stem support hole.

6. The motor-driven safety pressure relief valve for shale oil extraction and fracturing as claimed in claim 5, characterized in that: The upper end of the valve stem is an upper screw head, which is threadedly connected to the drive nut; the lower end of the pressure relief valve core is a lower support head, which is arranged in the valve stem support hole.

7. The motor-driven safety pressure relief valve for shale oil extraction and fracturing as claimed in claim 1, characterized in that: The pressure relief valve also includes an upper end cover, which is arranged between the valve body and the drive connection assembly. The inner circumference of the upper end cover is provided with a guide groove, and a guide key is fixedly provided on the upper part of the valve stem, and the guide key cooperates with the guide groove.

8. The motor-driven safety pressure relief valve for shale oil extraction and fracturing as claimed in claim 1, characterized in that: The cross-sectional size of the pressure relief valve core is larger than the cross-sectional size of the valve stem at the upper portion of the pressure relief valve core.

9. The motor-driven safety pressure relief valve for shale oil extraction and fracturing as claimed in claim 1, characterized in that: The valve stem sleeve cavity liquid inlet opening is arranged on the valve stem sleeve cavity with an upward tilt.

10. The motor-driven safety pressure relief valve for shale oil extraction and fracturing as claimed in claim 1, characterized in that: A sensor mounting hole is provided on one side wall of the valve chamber annular groove, and the pressure sensor is fixedly arranged in the sensor mounting hole.

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