Pulsating hydraulic fracturing device and construction method

Abstract

The invention discloses a pulsating hydraulic fracturing device and a construction method, and relates to the technical field of oil and gas field exploration and development, the pulsating hydraulic fracturing device comprises a pipe body, an elastic plunger and a driving mechanism, the two ends of the pipe body are used for being communicated with a fracturing pipe body, and fracturing fluid flows through the pipe body; the elastic plunger is arranged in the pipe body, the elastic plunger is in a positive cone ring shape, and the top end of the elastic plunger is sealed; the driving mechanism is connected with the top end of the elastic plunger, the driving mechanism can drive the elastic plunger to reciprocate between a first position and a second position, the elastic plunger with the positive cone ring-shaped top end is arranged, and the driving mechanism can drive the elastic plunger to reciprocate between the first position and the second position, so that pulsating fluid pressure is formed; and through deformation generated when the elastic plunger moves between the first position and the second position in a reciprocating mode, the fluid sectional area is rapidly changed, the pressure fluctuation period is shortened, weakening of inertia damping to the pressure amplitude is reduced, and the requirement for high-frequency and high-amplitude pulsating fluid pressure in engineering practice is met.

Description

Technical Field

[0001] This invention relates to the field of oil and gas field exploration and development technology, and in particular to a pulsed hydraulic fracturing device and construction method. Background Technology

[0002] In the fields of oil and gas, coalbed methane, and other energy extraction, as well as in the stimulation of low-permeability reservoirs such as shale and tight rock formations, hydraulic fracturing technology is a core means to improve reservoir permeability and enhance energy recovery efficiency. Traditional hydraulic fracturing technology injects high-pressure continuous fluid into the reservoir, using fluid pressure to create artificial fractures and form interconnected seepage channels. However, under the action of continuous high-pressure fluid, reservoir fractures often extend in the form of a single main fracture, with insufficient development of branch fractures. This results in a limited fracture network coverage, making it difficult to fully connect dispersed oil and gas reservoirs. Furthermore, high-pressure operations cause significant damage to the original reservoir structure, easily leading to safety hazards such as wellbore collapse.

[0003] To address the shortcomings of traditional continuous fracturing technology, pulsed hydraulic fracturing technology has emerged. Its core principle is to introduce periodic pulsating pressure into the fracturing fluid. Utilizing the alternating impact and unloading effects of this pressure, the fracture toughness of the reservoir rock is reduced, prompting the generation of more branch fractures around the main fracture, forming a complex fracture network. This significantly improves the connectivity between the reservoir and the wellbore. Existing pulsed hydraulic fracturing devices typically require the rotation of an impeller mounted on the cross-section of the pipe to change the fluid flow area. The magnitude of the pulsating fluid pressure is controlled by the impeller's rotation speed. Due to the significant inertia of the fracturing fluid, when the impeller rotates rapidly to change the flow path, the fluid cannot immediately respond to the change in cross-sectional area. This results in a prolonged pressure fluctuation period, and the pressure amplitude is weakened by inertial damping, failing to meet the requirements of high-frequency, high-amplitude pulsating fluid pressure in practical engineering applications. Summary of the Invention

[0004] The purpose of this invention is to provide a pulsating hydraulic fracturing device and construction method to solve the problems existing in the prior art and meet the needs of high-frequency, high-amplitude pulsating fluid pressure in engineering practice.

[0005] To achieve the above objectives, the present invention provides the following solution: This invention provides a pulsed hydraulic fracturing device, comprising a tube body, an elastic plunger, and a drive mechanism. The two ends of the tube body are connected and communicate with a fracturing tube body for fracturing fluid flow. The elastic plunger is disposed within the tube body and is a conical annular shape with a sealed top. The drive mechanism is connected to the top of the elastic plunger. The elastic plunger has a first state and a second state. The drive mechanism can drive the elastic plunger to reciprocate between the first and second positions. When the elastic plunger moves downward from the first position towards the second position, it is in the first state. When the elastic plunger moves upward from the second position towards the first position, it is in the second state. In the first state, the outer edge of the bottom of the elastic plunger circumferentially abuts against the inner wall of the tube body, and simultaneously, the inner conical surface of the elastic plunger applies pressure to the fracturing fluid at the bottom of the elastic plunger. In the second state, a circumferential gap exists between the outer edge of the bottom of the elastic plunger and the inner wall of the tube body to allow fracturing fluid to pass through.

[0006] In some embodiments, a transmission mechanism is also included, comprising a crankshaft and a connecting rod. The crankshaft is laterally disposed within the tube body, and its end is rotatably connected to the inner wall of the tube body. The crankshaft is drively connected to the drive mechanism. The first end of the connecting rod is hinged to the middle of the crankshaft, and the hinge point is spaced from the axis of the crankshaft. The second end of the connecting rod is rotatably connected to the top end of the elastic plunger. When the drive mechanism drives the crankshaft to rotate around the axis of the crankshaft, the connecting rod can drive the elastic plunger to reciprocate between a first position and a second position.

[0007] In some embodiments, the transmission mechanism further includes a guide rod, one end of which is rotatably connected to the second end of the connecting rod, and the other end of which is fixedly connected to the top end of the elastic plunger. A guide member is fixedly provided circumferentially on the guide rod, and the guide member has a through hole from the side near the elastic plunger to the side away from the elastic plunger for fracturing fluid to flow through. The circumferential sidewall of the guide member abuts against the inner sidewall of the tube body so that the elastic plunger moves along the axis of the tube body.

[0008] In some embodiments, a limiting platform is also fixedly provided inside the tube, and the guide rod passes through the limiting platform. The limiting platform is a conical annular shape with a vertical through hole at its axis. When the elastic plunger moves upward from the second position to the first position, the outer conical surface of the elastic plunger abuts against the bottom surface of the limiting platform.

[0009] In some embodiments, the transmission mechanism further includes an active bevel gear and a passive bevel gear. The body of the drive device is fixedly disposed in the tube. The output shaft of the drive device is parallel to the axis of the tube. The output shaft of the drive device is coaxially and fixedly connected to the active bevel gear. The passive bevel gear is fixedly sleeved on the crankshaft. The teeth of the active bevel gear and the passive bevel gear mesh with each other.

[0010] In some embodiments, the crankshaft includes a first crankshaft segment and a second crankshaft segment of equal length. The end of the first crankshaft segment near the inner wall of the tube is rotatably connected to the inner wall of the tube, and the end of the second crankshaft segment near the inner wall of the tube is rotatably connected to the inner wall of the tube. The end of the first crankshaft segment away from the inner wall of the tube is fixedly connected to the axis of a first eccentric wheel, and the end of the second crankshaft segment away from the inner wall of the tube is fixedly connected to the axis of a second eccentric wheel. The first eccentric wheel and the second eccentric wheel are parallel and perpendicular to the axis of the crankshaft. A pin is provided between the first eccentric wheel and the second eccentric wheel. The pin is parallel to the axis of the crankshaft and has a gap. The first end of the connecting rod is sleeved on the pin.

[0011] In some embodiments, a pressure sensor is provided at the bottom of the tube body, the pressure sensor being capable of measuring the fracturing fluid pressure at the bottom of the elastic plunger.

[0012] In some embodiments, threads are provided on the inner walls of both ends of the tube body for connecting and communicating the two ends of the tube body with the fracturing tube body.

[0013] In some embodiments, a controller is also included, which is signal-connected to the drive device and the pressure sensor.

[0014] This invention also provides a method for pulsating hydraulic fracturing, employing the pulsating hydraulic fracturing device described in any of the above claims, comprising: activating the driving device to drive the elastic plunger to reciprocate between a first position and a second position; when the elastic plunger moves downward from the first position toward the second position, the elastic plunger is in a first state, the elastic plunger is extended outward and the outer edge of the bottom of the elastic plunger abuts against the inner wall of the tube body, and simultaneously the inner cone surface of the elastic plunger applies pressure to the fracturing fluid at the bottom of the elastic plunger; when the elastic plunger moves upward from the second position toward the first position, the elastic plunger is in a second state, causing the fracturing fluid to flow downward from the circumferential gap between the outer edge of the bottom of the elastic plunger and the inner wall of the tube body.

[0015] The present invention achieves the following technical effects compared to the prior art: This invention provides a pulsed hydraulic fracturing device and construction method. When the elastic plunger moves downwards from a first position to a second position, it is in a first state. When the elastic plunger moves upwards from the second position back to the first position, it is in a second state. In the first state, the pressure of the fracturing fluid at the bottom of the elastic plunger is greater than the pressure of the fracturing fluid at the top of the elastic plunger. This pressure difference acts on the inner conical surface of the elastic plunger, causing the elastic plunger to expand outwards and its outer bottom edge to abut against the inner wall of the tubing. This prevents the fracturing fluid at the bottom of the elastic plunger from flowing upwards between the outer bottom edge of the elastic plunger and the inner wall of the tubing. Simultaneously, the inner conical surface of the elastic plunger applies pressure to the fracturing fluid at the bottom, causing it to flow towards the reservoir. In the second state, the pressure of the fracturing fluid at the bottom of the elastic plunger is less than the pressure of the fracturing fluid at the top of the elastic plunger. This pressure difference acts on the outer conical surface of the elastic plunger, causing the elastic plunger to contract inwards. This allows the fracturing fluid to flow downwards through the circumferential gap between the outer bottom edge of the elastic plunger and the inner wall of the tubing, increasing the elasticity. The volume of fracturing fluid at the bottom of the plunger is controlled by an elastic plunger with a positive conical annular shape and a sealed top. A drive mechanism allows the elastic plunger to reciprocate between a first and second position, creating pulsating fluid pressure. The deformation of the elastic plunger during this reciprocating motion rapidly changes the fluid flow area, shortens the pressure fluctuation cycle, and reduces the weakening of pressure amplitude due to inertial damping, thus meeting the needs of high-frequency, high-amplitude pulsating fluid pressure in engineering practice. Furthermore, when conventional fracturing fluid pressure is sufficient for hydraulic fracturing operations without the need for pulsating fracturing fluid, the elastic plunger is positioned in the second position. The fracturing fluid pressure flowing downwards along the pipe acts on the outer conical surface of the elastic plunger, causing it to contract inwards. This allows the fracturing fluid to flow downwards through the circumferential gap between the bottom outer edge of the elastic plunger and the inner wall of the pipe. This eliminates the need for frequent lifting of the fracturing pipe for installation and disassembly of the hydraulic fracturing device, improving its adaptability to various operating conditions. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the internal structure of the pulsating hydraulic fracturing device in some embodiments of Example 1; Figure 2 This is a cross-sectional view of the pulsating hydraulic fracturing device moving downwards from a first position toward a second position in some embodiments of Example 1. Figure 3This is a cross-sectional view of the pulsating hydraulic fracturing device moving upwards from the second position toward the first position in some embodiments of Example 1; In the figure: 1-pipe body; 11-limiting stage; 2-elastic plunger; 3-drive mechanism; 4-transmission mechanism; 41-crankshaft; 42-connecting rod; 43-guide rod; 431-guide component; 44-active bevel gear; 45-passive bevel gear; 5-pressure sensor. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] The purpose of this invention is to provide a pulsating hydraulic fracturing device and construction method to solve the problems existing in the prior art and meet the needs of high-frequency, high-amplitude pulsating fluid pressure in engineering practice.

[0020] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0021] Example 1 This embodiment provides a pulsed hydraulic fracturing device, including a tube body 1, an elastic plunger 2, and a drive mechanism 3. Both ends of the tube body 1 are connected and communicate with a fracturing tube body for fracturing fluid flow. The elastic plunger 2 is disposed inside the tube body 1 and is a conical annular shape, with its top sealed. The drive mechanism 3 is connected to the top of the elastic plunger 2. The elastic plunger 2 has a first state and a second state. The drive mechanism 3 can drive the elastic plunger 2 to reciprocate between the first and second positions. When the elastic plunger 2 moves downward from the first position to the second position, it is in the first state. When the elastic plunger 2 moves upward from the second position to the second position... When the elastic plunger 2 is in a first position, it is in the second state. In the first state, the pressure of the fracturing fluid at the bottom of the elastic plunger 2 is greater than the pressure of the fracturing fluid at the top of the elastic plunger 2. The pressure difference of the fracturing fluid acts on the inner conical surface of the elastic plunger 2, causing the elastic plunger 2 to expand outward and the outer edge of the bottom of the elastic plunger 2 to abut against the inner wall of the tube body 1, so as to prevent the fracturing fluid at the bottom of the elastic plunger 2 from flowing upward between the outer edge of the bottom of the elastic plunger 2 and the inner wall of the tube body 1. At the same time, the inner conical surface of the elastic plunger 2 applies pressure to the fracturing fluid at the bottom, so as to make the fracturing fluid flow towards the reservoir. In the second state, the pressure of the fracturing fluid at the bottom of the elastic plunger 2 is less than the pressure of the fracturing fluid at the top of the elastic plunger 2. The pressure difference of the fracturing fluid acts on the outer conical surface of the elastic plunger 2, causing the elastic plunger 2 to contract inward. This allows the fracturing fluid to flow downward through the circumferential gap between the bottom outer edge of the elastic plunger 2 and the inner wall of the tubing 1, increasing the volume of fracturing fluid at the bottom of the elastic plunger 2. By setting the elastic plunger 2 as a positive conical annular shape with a sealed top, and through the drive mechanism 3, the elastic plunger 2 can be driven to reciprocate between the first and second positions, forming pulsating fluid pressure. The deformation generated by the reciprocating motion of the elastic plunger 2 between the first and second positions rapidly changes the fluid flow area, shortens the pressure fluctuation period, and reduces the impact of inertial damping on the pressure amplitude. The reduced value meets the needs of high-frequency, high-amplitude pulsating fluid pressure in engineering practice; furthermore, when the conventional fracturing fluid pressure can meet the requirements of hydraulic fracturing construction without the need for pulsating fracturing fluid, the elastic plunger 2 is placed in the second position. The pressure of the fracturing fluid flowing downward along the pipe body 1 acts on the outer conical surface of the elastic plunger 2, causing the elastic plunger 2 to contract inward, so that the fracturing fluid flows downward from the circumferential gap between the bottom outer edge of the elastic plunger 2 and the inner wall of the pipe body 1. This eliminates the need to frequently lift the fracturing pipe body to install and disassemble the hydraulic fracturing device depending on whether pulsating hydraulic fracturing construction is required, thus improving the adaptability of the pulsating hydraulic fracturing device to the working conditions.

[0022] In some embodiments, the pulsating hydraulic fracturing device further includes a transmission mechanism 4, which includes a crankshaft 41 and a connecting rod 42. The crankshaft 41 is transversely disposed inside the pipe body 1 and its end is rotatably connected to the inner wall of the pipe body 1. The crankshaft 41 is connected to the drive mechanism 3. The first end of the connecting rod 42 is hinged to the middle of the crankshaft 41, and there is a gap between the hinge point and the axis of the crankshaft 41. The second end of the connecting rod 42 is rotatably connected to the top of the elastic plunger 2. When the drive mechanism 3 drives the crankshaft 41 to rotate around the axis of the crankshaft 41, the rotational motion is converted into reciprocating motion through the connecting rod 42, so that the elastic plunger 2 reciprocates between the first position and the second position to form pulsating fluid pressure.

[0023] In some embodiments, the transmission mechanism 4 further includes a guide rod 43, one end of which is rotatably connected to the second end of the connecting rod 42, and the other end of which is fixedly connected to the top end of the elastic plunger 2. A guide member 431 is fixedly provided circumferentially on the guide rod 43. The guide member 431 has a through hole from the side close to the elastic plunger 2 to the side away from the elastic plunger 2 for fracturing fluid to flow. The circumferential sidewall of the guide member 431 abuts against the inner sidewall of the tube body 1. The guide rod 43 causes the elastic plunger 2 to move along the axis of the tube body 1, preventing the center of the elastic plunger 2 from deviating from the axis of the tube body 1 during movement, thus affecting the sealing effect between the outer edge of the bottom of the elastic plunger 2 and the inner sidewall of the tube body 1.

[0024] In some embodiments, a limiting platform 11 is fixedly installed inside the tube body 1. The limiting platform 11 is a conical annular shape with a vertical through hole at its center. The guide rod 43 passes through the limiting platform 11. When the elastic plunger 2 moves upward from the second position to the first position, the outer conical surface of the elastic plunger 2 abuts against the bottom surface of the limiting platform 11 to limit the position of the elastic plunger 2 and maintain the stability of the shape of the elastic plunger 2. This prevents the outer edge of the bottom of the elastic plunger 2 from expanding outward at an excessive angle due to inertia when it changes from upward to downward movement, thus avoiding damage to the elastic plunger 2 caused by it getting stuck on the inner wall of the tube body 1. In some embodiments, the elastic plunger 2 is made of rubber.

[0025] In some embodiments, the transmission mechanism 4 further includes a driving bevel gear 44 and a driven bevel gear 45. The body of the drive mechanism 3 is fixedly disposed inside the pipe body 1. The output shaft of the drive mechanism 3 is parallel to the axis of the pipe body 1. The output shaft of the drive mechanism 3 is coaxially and fixedly connected to the driving bevel gear 44. The driven bevel gear 45 is fixedly sleeved on the crankshaft 41. The teeth of the driving bevel gear 44 and the driven bevel gear 45 mesh with each other. By aligning the output shaft of the drive mechanism 3 with the axis of the pipe body 1, the occupancy of the drive mechanism 3 on the cross-sectional area inside the pipe body 1 is reduced, allowing the fracturing fluid to flow smoothly. In some embodiments, the gear ratio of the driving bevel gear 44 to the driven bevel gear 45 is 1:3 to reduce the rotational speed output to the crankshaft 41 and increase the torque. In some embodiments, the drive mechanism 3 is waterproof and disposed inside the pipe body 1 via a support frame. The support frame has water passage holes to allow the fracturing fluid to flow smoothly.

[0026] In some embodiments, the crankshaft 41 includes a first crankshaft segment and a second crankshaft segment of equal length. The end of the first crankshaft segment near the inner wall of the tube body 1 is rotatably connected to the inner wall of the tube body 1, and the end of the second crankshaft segment near the inner wall of the tube body 1 is rotatably connected to the inner wall of the tube body 1. The end of the first crankshaft segment away from the inner wall of the tube body 1 is fixedly connected to the axis of the first eccentric wheel, and the end of the second crankshaft segment away from the inner wall of the tube body 1 is fixedly connected to the axis of the second eccentric wheel. The first eccentric wheel and the second eccentric wheel are parallel and both are perpendicular to the axis of the crankshaft. A pin is provided between the first eccentric wheel and the second eccentric wheel. The pin is parallel to the axis of the crankshaft and has a gap. The first end of the connecting rod 42 is sleeved on the pin so that the first end of the connecting rod 42 is hinged to the middle part of the crankshaft 41. In some embodiments, spiral guide grooves are symmetrically provided on opposite sides of the first and second eccentric wheels. The two ends of the pin can move along the guide grooves and be fixed at any position on the guide grooves to adjust the distance between the axis of the pin and the axis of the crankshaft, thereby changing the stroke of the elastic plunger 2 from the first position to the second position. When the crank radius of the crankshaft 41 is increased, the stroke of the elastic plunger 2 from the first position to the second position increases, thereby increasing the pressure amplitude of the pulsating fluid pressure and further meeting the needs of high-frequency, high-amplitude pulsating fluid pressure in engineering practice.

[0027] In some embodiments, a pressure sensor 5 is installed at the bottom of the inner tube 1. The pressure sensor 5 can measure the fracturing fluid pressure at the bottom of the elastic plunger 2. Based on the measured fracturing fluid pressure at the bottom of the elastic plunger 2, it is determined whether the actual fracturing fluid pressure has reached the preset fracturing fluid pressure. In some embodiments, the pulsating hydraulic fracturing device also includes a controller. The controller is signal-connected to the drive mechanism 3 and the pressure sensor 5. The controller can control the rotational speed of the drive mechanism 3, thereby controlling the frequency of the reciprocating motion of the elastic plunger 2 between the first and second positions, changing the frequency of the pulsating fluid pressure, and further meeting the needs of high-frequency, high-amplitude pulsating fluid pressure in engineering practice. In some embodiments, the drive mechanism 3 includes a drive motor.

[0028] In some embodiments, threads are provided on the inner walls of both ends of the pipe body 1 to connect and communicate the two ends of the pipe body 1 with the fracturing pipe body. Construction personnel can easily install or remove the pipe body 1 from the fracturing pipe body, and the threaded connection ensures the sealing of the fracturing fluid flow channel.

[0029] Example 2 This embodiment provides a pulsed hydraulic fracturing construction method, employing the pulsed hydraulic fracturing device from Embodiment 1, including: When the conventional fracturing fluid pressure can meet the requirements of hydraulic fracturing construction, that is, when the branch fractures are well developed and can fully connect the dispersed oil and gas reservoirs in the reservoir, the drive mechanism 3 is not started, the elastic plunger 2 is in the second position, the fracturing fluid pressure flowing downward along the pipe body 1 acts on the outer conical surface of the elastic plunger 2, the elastic plunger 2 contracts inward, so that the fracturing fluid flows downward from the circumferential gap between the bottom outer edge of the elastic plunger 2 and the inner wall of the pipe body 1; When the pressure of conventional fracturing fluid cannot meet the requirements of hydraulic fracturing operations, i.e., when the development of branch fractures is insufficient and the dispersed oil and gas reservoirs in the reservoir cannot be fully connected, the drive mechanism 3 is activated to drive the elastic plunger 2 to reciprocate between the first position and the second position. When the elastic plunger 2 moves downward from the first position to the second position, the elastic plunger 2 is in the first state, the elastic plunger 2 is extended outward and the outer edge of the bottom of the elastic plunger 2 abuts against the inner wall of the pipe body 1, and at the same time, the inner cone surface of the elastic plunger 2 applies pressure to the fracturing fluid at the bottom of the elastic plunger 2. When the elastic plunger 2 moves upward from the second position to the first position, the elastic plunger 2 is in the second state, the pressure of the fracturing fluid at the bottom of the elastic plunger 2 is less than the pressure of the fracturing fluid at the top of the elastic plunger 2, the pressure difference of the fracturing fluid acts on the outer cone surface of the elastic plunger 2, the elastic plunger 2 contracts inward, so that the fracturing fluid flows downward from the circumferential gap between the outer edge of the bottom of the elastic plunger 2 and the inner wall of the pipe body 1, thereby applying pulsating pressure to the fracturing fluid at the bottom of the elastic plunger 2.

[0030] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A pulsed hydraulic fracturing device, characterized in that: include: The tube body has two ends for connection and communication with the fracturing tube body and for the flow of fracturing fluid; An elastic plunger is disposed within the tube body. The elastic plunger is a positive conical annular shape, and the top of the elastic plunger is sealed. as well as A driving mechanism is connected to the top end of the elastic plunger. The elastic plunger has a first state and a second state. The driving mechanism can drive the elastic plunger to reciprocate between the first position and the second position. When the elastic plunger moves downward from the first position to the second position, it is in the first state. When the elastic plunger moves upward from the second position to the first position, it is in the second state. In the first state, the outer edge of the bottom of the elastic plunger abuts circumferentially against the inner wall of the tube body, and the inner cone surface of the elastic plunger applies pressure to the fracturing fluid at the bottom of the elastic plunger. In the second state, there is a circumferential gap between the outer edge of the bottom of the elastic plunger and the inner wall of the tube body to allow the fracturing fluid to pass through.

2. The pulsed hydraulic fracturing device according to claim 1, characterized in that: It also includes a transmission mechanism, which comprises: A crankshaft is arranged laterally within the tube body, with its end rotatably connected to the inner wall of the tube body. The crankshaft is also connected to the drive mechanism via a transmission connection. A connecting rod, the first end of which is hinged to the middle of the crankshaft and the hinge point is spaced from the axis of the crankshaft. The second end of the connecting rod is rotatably connected to the top of the elastic plunger. When the drive mechanism drives the crankshaft to rotate around the axis of the crankshaft, the connecting rod can drive the elastic plunger to reciprocate between a first position and a second position.

3. The pulsed hydraulic fracturing device according to claim 2, characterized in that: The transmission mechanism further includes a guide rod, one end of which is rotatably connected to the second end of the connecting rod, and the other end of which is fixedly connected to the top end of the elastic plunger. A guide member is fixedly provided circumferentially on the guide rod. The guide member has a through hole from the side near the elastic plunger to the side away from the elastic plunger for fracturing fluid to flow through. The circumferential sidewall of the guide member abuts against the inner sidewall of the tube body so that the elastic plunger moves along the axis of the tube body.

4. The pulsed hydraulic fracturing device according to claim 3, characterized in that: A limiting platform is also fixedly installed inside the tube, and the guide rod passes through the limiting platform. The limiting platform is a positive conical annular shape with a vertical through hole at its axis. When the elastic plunger moves upward from the second position to the first position, the outer conical surface of the elastic plunger abuts against the bottom surface of the limiting platform.

5. The pulsed hydraulic fracturing device according to claim 3, characterized in that: The transmission mechanism also includes a driving bevel gear and a driven bevel gear. The body of the drive device is fixedly installed in the tube. The output shaft of the drive device is parallel to the axis of the tube. The output shaft of the drive device is coaxially and fixedly connected to the driving bevel gear. The driven bevel gear is fixedly sleeved on the crankshaft. The teeth of the driving bevel gear and the driven bevel gear mesh with each other.

6. The pulsed hydraulic fracturing device according to claim 2, characterized in that: The crankshaft includes a first crankshaft segment and a second crankshaft segment of equal length. The end of the first crankshaft segment near the inner wall of the tube is rotatably connected to the inner wall of the tube, and the end of the second crankshaft segment near the inner wall of the tube is rotatably connected to the inner wall of the tube. The end of the first crankshaft segment away from the inner wall of the tube is fixedly connected to the axis of a first eccentric wheel, and the end of the second crankshaft segment away from the inner wall of the tube is fixedly connected to the axis of a second eccentric wheel. The first eccentric wheel and the second eccentric wheel are parallel and perpendicular to the axis of the crankshaft. A pin is provided between the first eccentric wheel and the second eccentric wheel. The pin is parallel to the axis of the crankshaft and has a gap. The first end of the connecting rod is sleeved on the pin.

7. The pulsed hydraulic fracturing device according to claim 1, characterized in that: A pressure sensor is installed at the bottom of the tube body, which can measure the fracturing fluid pressure at the bottom of the elastic plunger.

8. The pulsed hydraulic fracturing device according to claim 1, characterized in that: The inner walls at both ends of the tube are threaded to connect and communicate with the fracturing tube.

9. The pulsed hydraulic fracturing device according to claim 7, characterized in that: It also includes a controller, which is signal-connected to the drive unit and the pressure sensor.

10. A method for performing pulsed hydraulic fracturing, using the pulsed hydraulic fracturing device as described in any one of claims 1 to 9, characterized in that, include: The drive device is activated, driving the elastic plunger to reciprocate between a first position and a second position. When the elastic plunger moves downward from the first position to the second position, the elastic plunger is in the first state, with the elastic plunger extending outward and the outer edge of the bottom of the elastic plunger abutting against the inner wall of the tube. At the same time, the inner cone of the elastic plunger applies pressure to the fracturing fluid at the bottom of the elastic plunger. When the elastic plunger moves upward from the second position to the first position, the elastic plunger is in the second state, causing the fracturing fluid to flow downward from the circumferential gap between the outer edge of the bottom of the elastic plunger and the inner wall of the tube.

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