Pulsatile water pressure application device

Abstract

The application provides a pulsating water pressure applying device, which comprises a static pressure tank body and a dynamic pressure cylinder body arranged in the horizontal direction of a liquid delivery pipe in sequence, the air inlet of the static pressure tank body is connected with a high-pressure air source through an air delivery pipe, the dynamic pressure cylinder body is provided with a piston assembly and a servo motor for driving the piston assembly to move, and the liquid delivery pipe at the front end of the dynamic pressure cylinder body is inserted into the inside of a test piece; through the arrangement of the piston assembly and the servo motor, the servo motor can drive the piston assembly to make linear reciprocating motion in the dynamic pressure cylinder body, the piston assembly can change the pressure of the compressed gas in the dynamic pressure cylinder body during the movement in the dynamic pressure cylinder body, the pressure generated by the compressed gas is transmitted to the inside of the test piece through the liquid delivery pipe, so that the pulsating water pressure is generated in the inside of the test piece, and dynamic pressure hydraulic fracturing is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of pulsating water pressure device, and particularly relates to a pulsating water pressure applying device. BACKGROUND

[0002] Hydraulic fracturing technology refers to a method of forming cracks in an oil and gas reservoir by using hydraulic action, which is an important technical measure for increasing production of oil and gas wells and injection of water injection wells, and is widely used not only in low-permeability oil and gas reservoirs but also in the production and reconstruction of medium and high-permeability oil and gas reservoirs. Hydraulic fracturing is usually divided into ordinary hydraulic fracturing and pulsating hydraulic fracturing. In the process of pulsating hydraulic fracturing, the stress is periodically changed to damage the crack surface, which is beneficial to the extension of the crack, and thus the cracks can be formed under a smaller pressure.

[0003] In the prior art, a patent document with the application number 201611235577.6 and the publication date of July 27, 2018 and the name of 'continuous rotary valve pulsating hydraulic fracturing device and method' discloses a continuous rotary valve pulsating hydraulic fracturing device, which is composed of a water tank, a water injection pipeline, a water pump, a pressure relief pipeline, a continuous rotary ball valve and a hydraulic motor. In the process of cracking, after the continuous rotary valve is connected in the water injection pipeline, the valve core of the continuous rotary valve is rotated under the drive of the hydraulic motor, so that the valve is continuously and stably opened and closed, and stable pulsating water pressure is generated in the water injection pipeline. In this process, when the valve is closed, the high-pressure water in the coal rock body can actively reduce the pressure due to the development of micro cracks, and when the valve is opened, the water pressure in the coal rock body can be re-increased, thereby realizing the technical effect of pulsating water pressure. In the above process, the opening and closing of the valve are mainly controlled by the rotary valve. However, there is no effective control method or technology for the pressure reduction range of the high-pressure water after the valve is closed, the pressure increase efficiency after the valve is opened, and the stability of the pulsating water pressure effect is difficult to guarantee.

[0004] Therefore, it is necessary to design a new pulsating water pressure applying device to solve the above problems. SUMMARY

[0005] The present application aims to provide a pulsating water pressure applying device.

[0006] To achieve the above-mentioned application purposes, the present application provides a pulsating water pressure applying device, which comprises a static pressure tank body and a dynamic pressure cylinder body arranged in the horizontal direction of a liquid delivery pipe in sequence, a gas inlet of the static pressure tank body is connected with a high-pressure gas source through a gas delivery pipe, and the liquid delivery pipe at the front end of the dynamic pressure cylinder body is inserted into the inside of a test piece.

[0007] A liquid supplementing pump is arranged on the static pressure tank body, and a piston assembly and a servo motor for driving the piston assembly to move are arranged in the dynamic pressure cylinder body.

[0008] Preferably, the static pressure tank body is divided into an upper tank body and a lower tank body, the upper tank body is filled with pressure gas, and the lower tank body is filled with fracturing fluid.

[0009] Preferably, the bottom end of the static pressure tank body is provided with a one-way valve, and the other end of the one-way valve is connected with the liquid conveying pipe.

[0010] Preferably, one side of the lower tank body is connected with the liquid supplementing pump.

[0011] Preferably, the dynamic pressure cylinder body is divided into an upper cylinder body and a lower cylinder body, the upper cylinder body is filled with compressed gas, and the lower cylinder body is filled with the fracturing fluid.

[0012] Preferably, the piston assembly is arranged at the top end of the upper cylinder body, and the piston assembly is arranged above the compressed gas.

[0013] Preferably, the liquid conveying pipe is provided with a first valve at a position close to the one-way valve.

[0014] Preferably, the top surface of the static pressure tank body is provided with a first pressure detection device for detecting the pressure in the upper tank body.

[0015] Preferably, the liquid conveying pipe is provided with a second pressure detection device at a position close to the dynamic pressure cylinder body, and a second valve is arranged on the liquid conveying pipe close to the front end of the second pressure detection device.

[0016] Preferably, the top surface of the dynamic pressure cylinder body is provided with an air inlet valve.

[0017] The beneficial effects of the present application are as follows:

[0018] 1. The pulsating water pressure applying device provided by the present application comprises a static pressure tank body and a dynamic pressure cylinder body arranged in the horizontal direction of a liquid conveying pipe in sequence, the air inlet of the static pressure tank body is connected with a high-pressure gas source through a gas conveying pipe, the front end of the dynamic pressure cylinder body is inserted into the inside of a test piece, the inside of the dynamic pressure cylinder body is provided with a piston assembly, and the working state of the piston assembly is controlled by a servo motor arranged on the dynamic pressure cylinder body; the piston assembly can change the pressure of the compressed gas in the dynamic pressure cylinder body during the movement of the piston assembly in the dynamic pressure cylinder body, the pressure generated by the compressed gas is transmitted to the inside of the test piece through the liquid conveying pipe, thereby generating a pulsating water pressure in the inside of the test piece, and realizing dynamic water hydraulic fracturing; through the above-mentioned manner, the pulsating water pressure is continuously generated. In particular, the rotating speed of the servo motor can be adjusted to obtain pulsating water pressure with different frequencies according to the actual application requirements in the above-mentioned process; the balance position of the piston assembly, the reciprocating stroke of the piston assembly in the dynamic pressure cylinder body, and the volume ratio of the fracturing fluid to the pressure gas in the dynamic pressure cylinder body are adjusted to obtain pulsating water pressure with different amplitudes.

[0019] 2、The pulsating water pressure applying device provided by the present application can timely supplement the fracturing fluid into the dynamic pressure cylinder when the liquid level of the fracturing fluid in the dynamic pressure cylinder drops due to the cracks in the test piece, and can avoid the fracturing fluid flowing out of the static pressure tank from flowing back into the static pressure tank, so that the pressure of the dynamic pressure tank is kept stable during the whole process of generating the pulsating water pressure, the process of generating the pulsating water pressure is ensured to be stable, and finally stable pulsating water pressure is generated; the first pressure detection device is arranged on the static pressure tank, and the second pressure detection device is arranged on the liquid delivery pipe close to the dynamic pressure cylinder, so that the pressure of the gas in the static pressure tank and the dynamic pressure cylinder can be detected in real time, and the fracturing fluid can be supplemented into the dynamic pressure cylinder according to the monitoring result, so that the pressure of the gas in the static pressure tank and the dynamic pressure cylinder can be kept within a certain range. In the above manner, the pulsating water pressure applying device with simple structure, convenient operation and controllable amplitude and frequency stability is provided. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 FIG. 1 is a structural schematic view of the pulsating water pressure applying device of the present application;

[0021] The reference signs are as follows:

[0022] 1, static pressure tank; 101, upper tank; 102, lower tank; 2, dynamic pressure cylinder; 201, piston assembly; 3, high-pressure gas source; 4, liquid supplement pump; 5, servo motor; 6, one-way valve; 7, first pressure detection device; 8, gas inlet valve; 9, second pressure detection device; 10, gas delivery pipe; 11, liquid delivery pipe; 111, first valve; 112, second valve; 12, test piece. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application will be described in detail below with reference to the drawings and specific embodiments.

[0024] Here, it also needs to be explained that, in order not to obscure the present application due to unnecessary details, only the structures and / or processing steps closely related to the scheme of the present application are shown in the drawings, and other details not closely related to the present application are omitted.

[0025] In addition, it also needs to be explained that the term "comprise", "include" or any other variant thereof is intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or equipment.

[0026] Please refer to Figure 1As shown, the present application provides a pulsating water pressure applying device, which comprises a static pressure tank body 1 and a dynamic pressure cylinder body 2 arranged in the horizontal direction of the liquid delivery pipe 11 in sequence, the air inlet of the static pressure tank body 1 is connected with a high-pressure gas source 3 through a gas delivery pipe 10, and the liquid delivery pipe 11 at the front end of the dynamic pressure cylinder body 2 is inserted into the inside of a test piece 12.

[0027] Specifically, the static pressure tank body 1 is divided into an upper tank body 101 and a lower tank body 102, the lower tank body 102 is connected with a liquid supplement pump 4, the upper tank body 101 is provided with a first pressure detection device 7, the upper tank body 101 is filled with pressure gas, and the lower tank body 102 is filled with fracturing fluid; the bottom end of the lower tank body 102 is provided with a one-way valve 6, the one-way valve 6 can avoid the fracturing fluid in the static pressure tank body 1 from returning to the static pressure tank body 1 again, and the liquid delivery pipe 11 between the one-way valve 6 and the liquid delivery pipe 11 is provided with a first valve 111.

[0028] Further, the dynamic pressure cylinder body 2 is connected with a servo motor 5, the top surface of the dynamic pressure cylinder body 2 is provided with an air inlet valve 8, the internal space of the dynamic pressure cylinder body 2 is divided into an upper cylinder body and a lower cylinder body, the upper cylinder body is filled with compressed gas, the upper part of the upper cylinder body is provided with a piston assembly 201, the lower part of the piston assembly 201 is filled with compressed gas, the lower cylinder body is filled with fracturing fluid, and the fracturing fluid in the liquid delivery pipe 11 can be pressurized under the pushing of the piston assembly 201; in this way, the piston assembly 201 can be driven to move downward in the dynamic pressure cylinder body 2 under the driving of the servo motor 5, so as to change the volume of the compressed gas, and the pressure generated by the compressed gas is transmitted to the inside of the test piece 12 through the liquid delivery pipe 11, so as to generate a pulsating water pressure in the inside of the test piece 12, and realize dynamic water hydraulic fracturing; in addition, whether a fracture appears in the inside of the test piece 12 can be judged according to the change of the volume of the fracturing fluid in the lower cylinder body in the process. In particular, the liquid delivery pipe 11 near the front end of the second pressure detection device 9 is provided with a second valve 112, and the second pressure detection device 9 is arranged between the second valve 112 and the dynamic pressure cylinder body 2. It should be noted that the test piece 12 here refers to an implementation object to be fractured.

[0029] The working principle of the present application is as follows: when the pulsating water pressure applying device is applied, first, the infusion tube 11 is extended into the inside of the test piece 12, and the first valve 111 and the second valve 112 are opened, the fracturing fluid is injected into the lower tank body 102 of the static pressure tank body 1 by the liquid supplement pump 4, and the whole pipeline is filled with the fracturing fluid through the infusion tube 11; the second valve 112 is closed, the high-pressure gas is injected into the upper tank body 101 of the static pressure tank body 1 by the high-pressure gas source 3, and the pressure data in the upper tank body 101 is monitored in real time by the first pressure detection device 7, when the preset pressure is reached, the injection of the high-pressure gas is stopped, at the same time, according to the required pulsating water pressure amplitude, the piston assembly 201 is fixed at the target position in the dynamic pressure cylinder body 2; then, the high-pressure gas in the high-pressure gas source 3 is injected into the upper cylinder body of the dynamic pressure cylinder body through the air inlet valve 8, when the preset pressure is reached, the gas conveying pipe 10 connected with the air inlet valve 8 is disconnected; then, the servo motor 5 is started, and the initial data of the pulsating water pressure in the dynamic pressure cylinder body 2 is collected by the second pressure detection device 9; finally, the first valve 111 and the second valve 112 are in the opened state, the servo motor 5 is started, and the piston assembly 201 is driven to move downward under the action of the servo motor 5, at the same time, the pressure of the fracturing fluid in the lower cylinder body is generated, and the pressure is conveyed to the test piece 12 through the infusion tube 11, so that the pulsating water pressure is generated in the inside of the test piece 12, the dynamic pressure hydraulic fracturing is realized, and the frequency of the pulsating water pressure can be adjusted according to the actual needs by adjusting the rotating speed of the servo motor 5, the balance position of the piston assembly 201 and the reciprocating stroke of the piston assembly 201 in the dynamic pressure cylinder body 2, and the volume ratio of the fracturing fluid and the pressure gas in the dynamic pressure cylinder body 2, and different amplitude pulsating water pressures are obtained.

[0030] In particular, whether a fracture appears in the inside of the test piece 12 can also be judged according to the change of the volume of the fracturing liquid in the lower cylinder of the dynamic pressure cylinder 2 during the generation of the pulsating water pressure. Specifically, when no fracture appears in the inside of the test piece 12, the volume of the fracturing liquid in the lower cylinder does not change, only the pressure of the fracturing liquid in the delivery pipe 11 changes, and the fracturing liquid in the delivery pipe 11 cannot flow back to the static pressure tank 1 due to the presence of the one-way valve 6. When the piston assembly 201 moves to the lowest position of the lower part of the dynamic pressure cylinder 2, the pressure value of the pulsating water pressure reaches the maximum, and the piston assembly 201 reciprocates in the dynamic pressure cylinder 2 under the driving of the servo motor 5, periodically changing the pressure of the fracturing liquid in the delivery pipe 11, until a fracture appears in the inside of the test piece 12. When a fracture appears in the inside of the test piece 12, the fracturing liquid in the delivery pipe 11 enters the fracture in the inside of the test piece 12, causing the liquid level of the fracturing liquid in the lower cylinder to drop. When the piston assembly 201 moves to the highest position of the upper part, the gas pressure in the upper cylinder will be less than the preset value. At this time, the pressure of the gas in the upper tank 101 of the static pressure tank 1 is greater than the liquid pressure in the delivery pipe 11, which will push the fracturing liquid in the static pressure tank 1 to be injected into the delivery pipe 11 through the one-way valve 6, so that the gas pressure in the upper cylinder returns to the preset value, thereby maintaining the stability of the minimum value of the pulsating water pressure.

[0031] The pulsating water pressure applying device of the present application will be further described below in combination with specific embodiments:

[0032] Embodiment 1

[0033] The present embodiment provides a pulsating water pressure applying device, which comprises a static pressure tank 1 and a dynamic pressure cylinder 2 arranged in the horizontal direction of a delivery pipe 11 in sequence. The gas inlet of the static pressure tank 1 is connected with a high-pressure gas source 3 through a gas delivery pipe 10, and the delivery pipe 11 at the front end of the dynamic pressure cylinder 2 is inserted into the inside of a test piece 12. Specifically, the static pressure tank 1 is divided into an upper tank 101 and a lower tank 102, the lower tank 102 is connected with a liquid supplementing pump 4, the upper tank 101 is provided with a first pressure detecting device 7, the upper tank 101 is filled with pressure gas, and the lower tank 102 is filled with fracturing liquid. The bottom end of the lower tank 102 is provided with a one-way valve 6, which can avoid the fracturing liquid in the static pressure tank 1 from flowing back into the static pressure tank 1, and the delivery pipe 11 between the one-way valve 6 and the delivery pipe 11 is provided with a first valve 111.

[0034] Further, the infusion pipe 11 between the dynamic pressure cylinder 2 and the static pressure tank 1 is provided with a second valve 112, the second valve 112 is provided with a second pressure detection device 9 between the dynamic pressure cylinder 2, the dynamic pressure cylinder 2 is connected with the servo motor 5, the top surface of the dynamic pressure cylinder 2 is provided with an air inlet valve 8, the internal space of the dynamic pressure cylinder 2 is divided into an upper cylinder and a lower cylinder, the upper cylinder is filled with compressed gas, the upper part of the compressed gas is provided with a piston assembly 201, and the lower cylinder is filled with fracturing fluid; in this way, the piston assembly 201 can be driven to move downward in the dynamic pressure cylinder 2 under the driving of the servo motor 5, so as to change the volume of the compressed gas, and the gas pressure generated by the compressed gas is transmitted to the inside of the test piece 12 through the infusion pipe 11, and then whether a fracture appears in the test piece 12 can be judged according to the change of the volume of the fracturing fluid in the lower cylinder.

[0035] In summary, the pulsating water pressure applying device provided by the present application comprises a static pressure tank 1 and a dynamic pressure cylinder 2 arranged in the horizontal direction of the infusion pipe 11 in sequence, the air inlet of the static pressure tank 1 is connected with a high-pressure gas source 3 through a gas infusion pipe 10, and the infusion pipe 11 at the front end of the dynamic pressure cylinder 2 is inserted into the inside of a test piece 12. By arranging the piston assembly 201 and the servo motor 5, the piston assembly 201 can be driven to move linearly in the dynamic pressure cylinder 2 by the servo motor 5, the piston assembly 201 can change the pressure of the compressed gas in the dynamic pressure cylinder 2 during the movement in the dynamic pressure cylinder 2, the pressure generated by the compressed gas is transmitted to the inside of the test piece 12 through the infusion pipe 11, so as to generate a pulsating water pressure in the test piece 12, and realize dynamic water pressure fracturing. In the above manner, a pulsating water pressure applying device with simple structure, convenient operation and controllable pulsating water pressure is provided.

[0036] The above embodiments are only used to illustrate the technical solutions of the present application but not limit the present application, although the present application has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present application can be modified or replaced equivalently without departing from the spirit and scope of the technical solutions of the present application.

Claims

1. A device for applying pulsating water pressure, characterized in that, It includes a static pressure tank and a dynamic pressure cylinder arranged in sequence in the horizontal direction of the infusion pipe. The air inlet of the static pressure tank is connected to a high-pressure air source through an air supply pipe. The infusion pipe at the front end of the dynamic pressure cylinder is inserted into the test piece. The static pressure tank is equipped with a replenishment pump, and the dynamic pressure cylinder is equipped with a piston assembly and a servo motor for driving the piston assembly. The static pressure tank is divided into an upper tank and a lower tank. The upper tank is filled with pressurized gas, and the lower tank is filled with fracturing fluid. The dynamic pressure cylinder is divided into an upper cylinder and a lower cylinder. The upper cylinder is filled with compressed gas, and the lower cylinder is filled with fracturing fluid. The bottom of the static pressure tank is provided with a one-way valve, one end of which is connected to the bottom of the static pressure tank, and the other end of which is connected to the infusion pipe. One side of the lower tank is connected to the replenishment pump; The piston assembly is disposed at the top of the upper cylinder and above the compressed gas; A first valve is provided on the infusion tube near the one-way valve; The top surface of the static pressure tank is provided with a first pressure detection device, which is used to detect the pressure inside the upper tank. A second pressure detection device is provided on the infusion tube near the dynamic pressure cylinder, and a second valve is provided on the infusion tube near the front end of the second pressure detection device. When no cracks appear inside the test piece, the volume of fracturing fluid in the lower cylinder remains unchanged; only the pressure of the fracturing fluid in the delivery pipe changes. Due to the one-way valve, the fracturing fluid in the delivery pipe will not flow back into the static pressure tank. When the piston assembly moves to the lowest position at the bottom of the dynamic pressure cylinder, the pulsating water pressure reaches its maximum. Driven by the servo motor, the piston assembly reciprocates within the dynamic pressure cylinder, periodically changing the pressure of the fracturing fluid in the delivery pipe until cracks appear inside the test piece. When a crack appears inside the component, the fracturing fluid in the infusion pipe enters the crack inside the component under test, causing the liquid level of the fracturing fluid in the lower cylinder to drop. When the piston assembly moves to the highest point at the top, the gas pressure in the upper cylinder will be less than the preset value. At this time, the pressure of the gas in the upper tank of the static pressure tank is greater than the liquid pressure in the infusion pipe, which will push the fracturing fluid in the static pressure tank to be injected into the infusion pipe through the one-way valve, so that the gas pressure in the upper cylinder can be restored to the preset value, thereby maintaining the stability of the minimum value of the pulsating water pressure.

2. The pulsating water pressure application device according to claim 1, characterized in that, An air intake valve is provided on the top surface of the dynamic pressure cylinder.

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