Confining pressure control device and operation method thereof

Abstract

The invention relates to a confining pressure control device and an operation method thereof, and the device comprises a fine filter which is used for filtering liquid to be subjected to pressure control so as to settle solid impurity particles; the high-precision back pressure device comprises a back pressure body, an inner concave cavity and a balance liquid outlet channel are formed in the back pressure body, a piston type hydraulic balance structure is arranged in the inner concave cavity and the balance liquid outlet channel in a sliding mode, and the part, located above the hydraulic balance structure, of the inner concave cavity forms a pressure control cavity; the part, located below the hydraulic balance structure, of the inner concave cavity forms a front end liquid injection cavity; the pressure return body is communicated with a communication loop, the first end of the communication loop is communicated with the front-end liquid injection cavity, and the second end of the communication loop is communicated with the balance liquid outlet channel; and the automatic constant pressure pump applies constant pressure into the pressure control cavity. According to the invention, liquid to be subjected to pressure control can be filtered, pressure regulation and control are realized, input cost is reduced, man-machine separation is realized, safety is guaranteed, experiment precision is improved, larger confining pressure is provided, the confining pressure is stable, and the service life is longer.

Description

Technical Field

[0001] The present invention relates to the technical field of throttle valves, and in particular to a confining pressure control device and an operating method thereof. Background Art

[0002] With the continuous development of drilling and oil production technology, the depth of drilling is increasing. When the well reaches a certain depth, new supporting downhole tools need to be developed. Downhole tools need to undergo high-pressure confining pressure simulation experiments during the research and development process. The current confining pressure simulation experiment generally maintains the front-end pressure through a throttle valve or a throttle valve plus an accumulator. This solution has several shortcomings:

[0003] First, the confining pressure that can be simulated is relatively low, and it is difficult to simulate a confining pressure of 60 to 100 MPa.

[0004] Second, it is sensitive to viscosity. The relief valve maintains unstable pressure for fluids with large viscosity changes and low viscosity.

[0005] Third, the working fluid in the confining pressure simulation experiment usually contains sand, which will cause serious wear to the valve core of the throttle valve under the high-speed and high-pressure working environment, thereby causing instability in the confining pressure. At the same time, the wear will greatly reduce the service life of the throttle valve.

[0006] Fourth, the pressure control is mostly manual, and it is difficult to adjust the pressure accurately; and in the case of manual adjustment, the separation between man and machine cannot be achieved, and there is a certain risk factor.

[0007] The prior art discloses a method for regulating pressure by a hydraulic cylinder, which has the problems of complex control logic and high hardware requirements, and the pressure is unstable when the investment is insufficient. In summary, there is currently a lack of a low-cost and stable confining pressure control method.

[0008] Therefore, the inventor, relying on many years of experience and practice in related industries, proposes a confining pressure control device and an operating method thereof to overcome the defects of the prior art. Summary of the invention

[0009] The object of the present invention is to provide a confining pressure control device and an operating method thereof, so as to overcome the problems in the prior art such as low simulated confining pressure, sensitivity to liquid viscosity, severe wear, and inability to automatically control. The present invention can filter the liquid to be controlled, and achieve pressure regulation with a relatively simple structure, thereby reducing investment costs, and can achieve human-machine separation to ensure safety, thereby providing protection for related experiments that need to be conducted under confining pressure conditions, improving the accuracy of the experiments, and providing greater confining pressure, stable confining pressure, and longer service life.

[0010] The object of the present invention is achieved by providing a confining pressure control device, comprising:

[0011] Fine filter, used to filter the liquid to be pressure controlled to allow solid impurity particles to settle;

[0012] A high-precision back-pressure device comprises a back-pressure body, wherein an inner concave chamber and a balanced liquid outlet channel are arranged in the back-pressure body, wherein a piston-type hydraulic balance structure can be slidably arranged in the inner concave chamber and the balanced liquid outlet channel, wherein the portion of the inner concave chamber located above the hydraulic balance structure constitutes a pressure control chamber; the portion of the inner concave chamber located below the hydraulic balance structure constitutes a front-end liquid injection chamber; the back-pressure body is connected with a connecting circuit, wherein a first end of the connecting circuit is connected with the front-end liquid injection chamber, and a second end of the connecting circuit is connected with the balanced liquid outlet channel, wherein a back-pressure body inlet connected with the fine filter is arranged on the connecting circuit; an automatic constant pressure pump is connected with the pressure control chamber, wherein the automatic constant pressure pump applies a constant pressure to the pressure control chamber, and the hydraulic balance structure slides under the pressure difference between the pressure control chamber and the front-end liquid injection chamber to control the opening of the balanced liquid outlet channel.

[0013] In a preferred embodiment of the present invention, the back pressure body comprises a valve body, the lower part of the valve body is sealed and connected to the lower seat, the top end of the valve body is downwardly provided with the inner concave chamber, and the bottom end of the inner concave chamber is downwardly provided with a first communication hole;

[0014] A valve core cavity is upwardly arranged at the bottom end of the lower seat, a second communication hole connected to the first communication hole is upwardly penetrated through the top end of the valve core cavity, a valve core is arranged in the valve core cavity, a third communication hole is penetrated through the valve core, the bottom end of the valve core cavity is connected to the lower joint, and a fourth communication hole is penetrated through the lower joint;

[0015] A fifth communicating hole penetrating to the second communicating hole is provided on the side wall of the lower seat, the fifth communicating hole is connected to the second end of the communicating loop, and the first communicating hole, the second communicating hole, the third communicating hole, the fourth communicating hole and the fifth communicating hole are connected to form the balanced liquid outlet channel;

[0016] The hydraulic balance structure includes a piston slidably disposed in the inner concave chamber, the bottom end of the piston is connected to a valve needle, the valve needle is slidably disposed in the first connecting hole and the second connecting hole, the valve needle penetrates the valve body and the lower seat; and the bottom end of the valve needle can block the third connecting hole of the valve core, or can slide away from the third connecting hole to change the opening of the balanced liquid outlet channel.

[0017] In a preferred embodiment of the present invention, the connecting circuit includes a U-shaped tube, and the two straight tube portions of the U-shaped tube are horizontally arranged; the first end of the U-shaped tube is connected to the bottom end of the concave chamber, and the second end of the U-shaped tube is connected to the fifth connecting hole and the fine filter.

[0018] In a preferred embodiment of the present invention, a three-way joint is provided at the second end of the U-shaped tube, the first interface of the three-way joint is connected to the U-shaped tube, the second interface of the three-way joint constitutes the inlet of the back-pressure body, and the third interface of the three-way joint is connected to the fifth connecting hole through a straight joint.

[0019] In a preferred embodiment of the present invention, a sixth communicating hole is provided in the valve body, a first end of the sixth communicating hole is communicated with the first end of the U-shaped tube, and a second end of the sixth communicating hole is communicated with the bottom end of the concave chamber.

[0020] In a preferred embodiment of the present invention, the first end of the U-shaped tube is sealed and connected to the sixth connecting hole through a plug and a pressure cap, and the second end of the U-shaped tube is connected to the first interface of the three-way joint through a plug and a pressure cap.

[0021] In a preferred embodiment of the present invention, an inner groove is provided at the bottom end of the piston, and the second end of the sixth communicating hole is provided corresponding to the inner groove.

[0022] In a preferred embodiment of the present invention, a pressure pad is provided between the valve core and the lower joint.

[0023] In a preferred embodiment of the present invention, the maximum working pressure of the high-precision back pressure device is 105MPa, the confining pressure stability accuracy is ±1MPa, the working ambient temperature is 0-50°C, and the maximum allowable flow rate is 30L / min.

[0024] In a preferred embodiment of the present invention, the fine filter includes a cylinder body, a filter center hole is set through the cylinder body, a filter liquid inlet is set on the side wall of the cylinder body, two ends of the filter center hole are respectively sealed and connected to a first cover body and a second cover body, a hollow filter element is axially arranged in the center hole of the filter, and two ends of the filter element are laid on the first cover body and the second cover body; a filter annulus is formed between the outer wall of the filter element and the side wall of the center hole of the filter, and the filter liquid inlet is connected with the filter annulus; a cover body through hole connected with the inner cavity of the filter element is set on the second cover body, and the cover body through hole constitutes the filter liquid outlet, and the liquid to be controlled is filtered through the filter inlet and the filter annulus by the filter element.

[0025] In a preferred embodiment of the present invention, the maximum working pressure of the fine filter is 105 MPa, the filtration accuracy is 3 μm, and the maximum allowable flow rate is 30 L / min.

[0026] In a preferred embodiment of the present invention, the liquid inlet of the filter is connected to a control valve, and the inlet of the control valve is connected to a four-way joint.

[0027] In a preferred embodiment of the present invention, the automatic constant pressure pump is connected to a pressure sensor, and the pressure sensor is used to detect the real-time pressure of the automatic constant pressure pump.

[0028] In a preferred embodiment of the present invention, the automatic constant pressure pump is electrically connected to the control cabinet.

[0029] In a preferred embodiment of the present invention, a right-angle needle valve is provided on the automatic constant pressure pump, and the right-angle needle valve is used for exhausting the automatic constant pressure pump.

[0030] In a preferred embodiment of the present invention, the automatic constant pressure pump is controlled by a PLC data acquisition system, with a maximum working pressure of 105MPa, a displacement range of 0.001 to 42ml / min, a constant pressure accuracy of ±0.1MPa, a tracking accuracy of ±0.1MPa, a pressure tracking speed of 3MPa / s, and an ambient temperature of 0°C to 50°C.

[0031] In a preferred embodiment of the present invention, it further comprises a frame, on which a support plate is arranged, and on which the fine filter, the high-precision back pressure device and the automatic constant pressure pump are arranged.

[0032] The object of the present invention can also be achieved in this way. A method for operating a confining pressure control device comprises: after the pressure-controlled liquid of the controlled pressure system is filtered by a fine filter, it flows into the connecting circuit of the high-precision back pressure device, one path of liquid flows to the fifth connecting hole of the lower seat, and the other path of liquid flows to the front end liquid injection cavity below the piston in the inner concave cavity of the valve body, and the pressure at the bottom of the piston is equal to the front end pressure of the device;

[0033] When the pressure at the bottom of the piston is greater than the pressure applied to the pressure control chamber by the automatic constant pressure pump, the piston is pushed upward and drives the valve needle to move upward, that is, the opening between the valve core and the valve needle increases, so that the outlet area of ​​the balanced liquid outlet channel increases, the high-precision back pressure device releases pressure, and the front end pressure decreases;

[0034] When the pressure at the bottom of the piston is less than the pressure applied to the pressure control chamber by the automatic constant pressure pump, the piston is pushed downward to drive the valve needle downward, that is, the opening between the valve core and the valve needle is reduced, so that the outlet area of ​​the balanced liquid outlet channel is reduced, the high-precision back pressure device is pressurized, and the front end pressure is increased;

[0035] After the front end pressure is increased or decreased and adjusted, it reaches the pressure equal to that of the automatic constant pressure pump, and the upper and lower pressures of the piston are equal and stop moving;

[0036] When the front pressure changes, the piston repeats the above steps under the action of the upper and lower pressure difference, so that the pressure below the piston is equal to the pressure of the automatic constant pressure pump, achieving dynamic balance of the confining pressure.

[0037] As described above, the confining pressure control device and the operating method thereof of the present invention have the following beneficial effects:

[0038] The fine filter of the present invention can filter the liquid to be pressure-controlled entering the device, so that solid impurity particles are settled to avoid entering the subsequent structure and causing wear;

[0039] The high-precision back pressure device of the present invention controls the opening of the balanced liquid outlet channel through the sliding of a piston-type hydraulic balance structure, and the automatic constant pressure pump provides a constant back pressure to the pressure control chamber above the hydraulic balance structure, thereby realizing pressure regulation, and the pressure regulation is automated, so that human-machine separation is achieved and safety is guaranteed; the surrounding pressure is regulated by adjusting the pressure of the automatic constant pressure pump, and the surrounding pressure is larger and more stable, which satisfies a wider range of simulated surrounding pressure; the high-precision back pressure device is not a high-precision hydraulic device, and is insensitive to liquid viscosity, so that the pressure stability will not be affected by liquid viscosity; compared with a hydraulically controlled surrounding pressure control system, the cost is lower, the control principle is simpler, and the surrounding pressure is more stable;

[0040] The invention has a simple overall structure, good sealing performance, quick and convenient adjustment and easy maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The following drawings are only intended to illustrate and explain the present invention, and are not intended to limit the scope of the present invention.

[0042] in:

[0043] Figure 1 : is an overall schematic diagram of the confining pressure control device of the present invention.

[0044] Figure 2 : It is a three-dimensional structural diagram of the confining pressure control device of the present invention.

[0045] Figure 3 : is a cross-sectional view of the fine filter of the present invention.

[0046] Figure 4 : is the appearance diagram of the fine filter of the present invention.

[0047] Figure 5 : is a cross-sectional view of the high-precision back pressure device of the present invention.

[0048] Figure 6 : is the appearance diagram of the high-precision back pressure device of the present invention.

[0049] In the figure:

[0050] 1. Fine filter;

[0051] 11. Cylinder body; 12. Filter liquid inlet; 13. First cover body; 14. Second cover body; 15. Filter element; 16. Sealing retaining ring;

[0052] 2. High-precision back pressure device;

[0053] 20. Pressure control chamber; 21. Connecting circuit; 211. U-shaped tube; 212. Three-way joint; 213. Straight joint; 214. Plug; 215. Pressure cap; 22. Valve body; 23. Lower seat; 24. Valve core; 25. Lower joint; 26. Piston; 261. Inner groove; 27. Valve needle; 28. Pressure pad; 29. ​​Upper cover plate;

[0054] 3. Automatic constant pressure pump; 31. Right angle needle valve;

[0055] 4. Control valve;

[0056] 5. Four-way connector;

[0057] 6. Elbow joint;

[0058] 7. Pressure sensor;

[0059] 8. Control chassis;

[0060] 9. Frame; 91. Pallet. DETAILED DESCRIPTION

[0061] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described with reference to the accompanying drawings.

[0062] The specific embodiments of the present invention described herein are only used to explain the purpose of the present invention and cannot be understood as limiting the present invention in any way. Under the guidance of the present invention, technicians can conceive of any possible variations based on the present invention, which should be considered to belong to the scope of the present invention. It should be noted that when an element is referred to as "arranged on" another element, it can be directly on the other element or there can also be a central element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be a central element at the same time. The terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a mechanical connection or an electrical connection, or it can be the internal communication of two elements, it can be directly connected, or it can be indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to the specific circumstances. The terms "vertical", "horizontal", "up", "down", "left", "right" and similar expressions used herein are only for illustrative purposes and do not represent the only implementation method.

[0063] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0064] like Figures 1 to 6 As shown, the present invention provides a confining pressure control device, comprising:

[0065] A fine filter 1, used for filtering the liquid to be pressure-controlled to allow solid impurity particles to settle;

[0066] The high-precision back pressure device 2 comprises a back pressure body, wherein an inner concave chamber and a balanced liquid outlet channel are arranged in the back pressure body, a piston-type hydraulic balance structure can be slidably arranged in the inner concave chamber and the balanced liquid outlet channel, the part of the inner concave chamber located above the hydraulic balance structure constitutes a pressure control chamber 20; the part of the inner concave chamber located below the hydraulic balance structure constitutes a front-end liquid injection chamber; a connecting circuit 21 is connected to the back pressure body, a first end of the connecting circuit 21 is connected to the front-end liquid injection chamber, a second end of the connecting circuit 21 is connected to the balanced liquid outlet channel, and a back pressure body inlet connected to the fine filter 1 is arranged on the connecting circuit 21;

[0067] The automatic constant pressure pump 3 is connected to the pressure control chamber. The automatic constant pressure pump applies a constant pressure to the pressure control chamber. The hydraulic balance structure slides under the pressure difference between the pressure control chamber and the front-end liquid injection chamber to control the opening of the balance liquid outlet channel. When the pressure of the front-end pressure-controlled liquid entering the front-end liquid injection chamber through the back-pressure body inlet is lower than the pressure of the automatic constant pressure pump 3, the hydraulic balance structure moves down, the opening of the balance liquid outlet channel decreases, and the system is pressurized; when the pressure of the front-end pressure-controlled liquid entering the front-end liquid injection chamber through the back-pressure body inlet is higher than the pressure of the automatic constant pressure pump 3, the hydraulic balance structure moves up, the opening of the balance liquid outlet channel increases, and the system is depressurized, and finally a dynamic balance is achieved to stabilize the front-end pressure. Compared with the confining pressure control system controlled by hydraulic pressure, it has lower cost, simpler control principle, and more stable confining pressure. It is also simpler and less complicated than the throttle valve control that requires manual adjustment. The automatic constant pressure pump can be connected to a computer, and computer control can realize remote control.

[0068] The fine filter 1 is mainly used to prevent the primary desander and the secondary desander (existing technology) from not removing sand thoroughly enough, causing some fine sand particles to flow into the high-precision back pressure device and damage the high-precision back pressure device.

[0069] The fine filter of the present invention can filter the liquid to be pressure-controlled entering the device, so that solid impurity particles are settled to avoid entering the subsequent structure and causing wear;

[0070] The high-precision back pressure device of the present invention controls the opening of the balanced liquid outlet channel through the sliding of a piston-type hydraulic balance structure, and the automatic constant pressure pump provides a constant pressure to the pressure control chamber above the hydraulic balance structure to achieve pressure regulation, and the pressure regulation is automated, so that human-machine separation is achieved and safety is guaranteed; the surrounding pressure is adjusted by adjusting the pressure of the automatic constant pressure pump, and the surrounding pressure is larger and more stable, which can meet a wider range of simulated surrounding pressure; the high-precision back pressure device is not a high-precision hydraulic device, and is insensitive to liquid viscosity, so that the pressure stability will not be affected by liquid viscosity; compared with the surrounding pressure control system controlled by hydraulic pressure, the cost is lower, the control principle is simpler, and the surrounding pressure is more stable;

[0071] The invention has a simple overall structure, good sealing performance, quick and convenient adjustment and easy maintenance.

[0072] Further, if Figure 5 , Figure 6 As shown, the high-precision back pressure device 2 is the core component of the confining pressure control device, and adopts a piston-type structural design. A liquid inlet is arranged on the side of the back pressure body, and a liquid outlet is arranged on the bottom.

[0073] The back pressure body includes a valve body 22, the lower part of the valve body 22 is sealed and connected to the lower seat 23, and an O-ring is used between the valve body 22 and the lower seat 23; a concave chamber is arranged downwardly at the top of the valve body 22, and a first communication hole is arranged downwardly through the bottom of the concave chamber;

[0074] A valve core cavity is arranged upward from the bottom end of the lower seat 23, a second communication hole connected to the first communication hole is arranged through the top end of the valve core cavity, a valve core 24 is arranged in the valve core cavity, a third communication hole is arranged through the valve core 24, a lower joint 25 is threadedly connected to the bottom end of the valve core cavity, a fourth communication hole is arranged through the lower joint 25, and an outlet of the fourth communication hole constitutes a liquid outlet; the lower joint 25 can be connected to a water tank (existing technology);

[0075] A fifth communication hole is provided on the side wall of the lower seat 23 and is connected to the second communication hole (i.e., a channel for liquid outflow is designed on the side of the lower seat). The fifth communication hole is connected to the second end of the external communication circuit 21, and the inlet of the fifth communication hole constitutes the liquid inlet; the first communication hole, the second communication hole, the third communication hole, the fourth communication hole and the fifth communication hole are connected to form a balanced liquid outlet channel;

[0076] The hydraulic balance structure includes a piston 26 slidably disposed in the inner concave chamber, and the contact surface between the piston 26 and the inner concave chamber is sealed with an O-ring; the bottom end of the piston 26 is connected to a valve needle 27, which is slidably disposed in the first and second communication holes, and the valve needle 27 penetrates the valve body 22 and the lower seat 23; and the bottom end of the valve needle 27 can block the third communication hole of the valve core 24, or can slide away from the third communication hole to change the opening of the balance liquid outlet channel. The contact surface between the valve needle 27 and the valve body 22 is provided with multiple cushions and O-rings to ensure sealing.

[0077] The outer diameter of the valve needle 27 is slightly smaller than the aperture of the second communication hole, and an annular gap is formed between the outer wall of the valve needle 27 and the side wall of the second communication hole, and the liquid can flow downward through the fifth communication hole and the annular gap. The blocking of the third communication hole of the valve core 24 by the valve needle 27 can change as it moves, thereby changing the opening of the overall balanced liquid outlet channel.

[0078] The valve needle 27 moves up and down with the piston 26 to control the opening size of the balanced liquid outlet channel, and cooperates with the valve core 24 to just seal the balanced liquid outlet channel when the piston 26 is at the bottom of the concave chamber.

[0079] In order to achieve dynamic adjustment of the valve opening, the valve core 24 of the high-precision back pressure device 2 has a lower material hardness than the valve needle 27, which plays a buffering role and ensures the sealing of the liquid outlet when it is closed to prevent liquid leakage. The valve core 24 will wear out under the erosion of water flow for a long time and needs to be replaced. When replacing the valve core 24, you only need to unscrew the lower joint 25 to remove the valve core 24.

[0080] An O-ring is provided at the position where the valve core 24 contacts the lower seat 23 .

[0081] The present invention has stable control and simple structure. It adopts piston structure design. The valve needle 27 is installed at the bottom of the piston 26, and the upper part of the piston 26 is connected to an automatic constant pressure pump. The side of the back pressure body is provided with a liquid inlet, and the bottom is provided with a liquid outlet. When the liquid inlet pressure is higher than the pressure at the upper part of the piston 26, the piston pushes up, the opening of the balanced liquid outlet channel increases, and the system automatically releases pressure. When the liquid inlet pressure is lower than the pressure at the upper part of the piston 26, the piston presses down, the opening of the balanced liquid outlet channel decreases, and the system is pressurized, and finally a dynamic balance is achieved to stabilize the front-end pressure. Compared with the confining pressure control system controlled by hydraulic pressure, the cost is lower, the control principle is simpler, and the confining pressure is more stable. It is also simpler and less complicated than the throttle valve control that needs to be manually adjusted.

[0082] Further, if Figure 5 , Figure 6 As shown, the connecting loop 21 includes a U-shaped tube 211, and the two straight tube parts of the U-shaped tube 211 are arranged horizontally; the first end of the U-shaped tube 211 is connected to the bottom end of the concave chamber, that is, the front end liquid injection cavity, and the second end of the U-shaped tube 211 is connected to the fifth connecting hole and the fine filter 1.

[0083] Further, if Figure 5 , Figure 6 As shown, a three-way joint 212 is provided at the second end of the U-shaped tube 211, the first interface of the three-way joint 212 is connected to the U-shaped tube 211, the second interface of the three-way joint 212 constitutes the inlet of the back pressure body, and the third interface of the three-way joint 212 is connected to the fifth connecting hole through a straight joint 213 (external thread straight joint).

[0084] Further, if Figure 5 As shown, a sixth communicating hole is provided in the valve body 22 , a first end of the sixth communicating hole is communicated with a first end of the U-shaped tube 211 , and a second end of the sixth communicating hole is communicated with a bottom end of the concave chamber.

[0085] Further, the first end of the U-shaped tube 211 is sealed and connected to the sixth communication hole through the plug 214 and the pressure cap 215, and the second end of the U-shaped tube is connected to the first interface of the three-way joint through the plug 214 and the pressure cap 215. The plug 214 is sealed to prevent liquid leakage, and the pressure cap 215 is used for decoration.

[0086] Further, if Figure 5 As shown, the bottom end of the piston 26 is provided with an inner groove 261 (i.e., the lower part of the piston 26 is hollowed out), and the second end of the sixth communication hole is provided corresponding to the inner groove 261. When the piston 26 is located at the bottom of the inner concave chamber, there can also be a cavity to ensure that the liquid can flow to the bottom of the piston along the U-shaped tube 211.

[0087] Further, if Figure 5 As shown, a pressure pad 28 is arranged between the valve core 24 and the lower joint 25 to further buffer the movement of the valve needle 27. A liquid through hole is arranged through the pressure pad 28 to ensure smooth flow of liquid.

[0088] Further, if Figure 5 As shown, the top of the concave chamber is sealed and connected with an upper cover plate 29, and an automatic constant pressure pump 3 is connected to the upper cover plate 29 to apply a constant pressure thereto.

[0089] Furthermore, the maximum working pressure of the high-precision back pressure device is 105MPa, the confining pressure stability accuracy is ±1MPa, the working ambient temperature is 0-50°C, and the maximum allowable flow rate is 30L / min.

[0090] Further, if Figure 3 , Figure 4 As shown, the fine filter 1 includes a cylinder body 11, a filter center hole is set through the cylinder body 11, a filter liquid inlet 12 is set on the side wall of the cylinder body 11, two ends of the filter center hole are sealed and connected to a first cover body 13 and a second cover body 14 respectively, a hollow filter element 15 is axially arranged in the filter center hole, and two ends of the filter element 15 are laid on the first cover body 13 and the second cover body 14; a filter annulus is formed between the outer wall of the filter element 15 and the side wall of the filter center hole, and the filter liquid inlet 12 is connected with the filter annulus; a cover body through hole connected with the inner cavity of the filter element 15 is set on the second cover body 14, and the cover body through hole constitutes the filter liquid outlet, and the liquid to be controlled is filtered through the filter liquid inlet 12 and the filter annulus by the filter element 15.

[0091] The central axis of the fine filter 1 is vertically arranged, the second cover 14 is the upper cover, and the first cover 13 is the lower cover. The first cover 13 and the second cover 14 of the fine filter 1 are connected to the cylinder body 11 by interference fit, and are sealed with an O-ring and a sealing retaining ring 16. A groove that meets the size of the filter element 15 is designed between the first cover 13 and the second cover 14. The filter element 15 is an ultra-high pressure filter element. Both ends of the filter element 15 are installed in the grooves of the first cover 13 and the second cover 14, and both ends are sealed with O-rings. The liquid to be controlled enters the fine filter 1 from the filter inlet 12, and the solid impurity particles are filtered by the filter element 15 to settle on the first cover 13 outside the filter element 15. The filtered liquid is discharged from the cover through hole on the second cover 14, and the cover through hole is connected to the high-precision back pressure device 2.

[0092] Furthermore, the maximum working pressure of the fine filter 1 is 105 MPa, the filtering accuracy is 3 μm, and the maximum allowable flow rate is 30 L / min.

[0093] In view of the defects of the prior art that the components are sensitive to viscosity and easy to wear, the present invention is convenient and quick to disassemble and assemble the components that need to be replaced. In order to realize the dynamic adjustment of the valve opening, the valve core of the high-precision back pressure device has a lower material hardness than the valve needle. It will wear out under the long-term erosion of the water flow and needs to be replaced. When replacing the valve core, you only need to unscrew the lower joint to remove the valve core. The filter element of the fine filter needs to be replaced after long-term use. You only need to open the first cover body 13 (lower cover) of the fine filter 1, pull out the filter element, insert the new valve core into the center hole of the filter, and then tighten the first cover body 13.

[0094] Further, if Figure 1 , Figure 2 As shown, the filter liquid inlet 12 is connected to the control valve 4 , and the control valve 4 can open and close the channel for liquid to flow into the fine filter 1 .

[0095] The inlet of the control valve 4 is connected to the four-way joint 5. One interface of the four-way joint 5 is connected to the system where the pressure-controlled liquid is located, one interface can be connected to other experimental equipment, one interface serves as a safety pressure relief valve of the system to discharge pressure when necessary to ensure safety, and one interface is connected to the control valve 4.

[0096] In order to facilitate the connection between the control valve 4 and the fine filter 1 , the inlet of the fine filter 1 is connected to the elbow joint 6 .

[0097] Further, if Figure 1 As shown, the automatic constant pressure pump 3 is connected to a pressure sensor 7 , and the pressure sensor 7 is used to detect the real-time pressure of the automatic constant pressure pump 3 .

[0098] Further, if Figure 1 , Figure 2As shown, the automatic constant pressure pump 3 is electrically connected to the control box 8.

[0099] The automatic constant pressure pump 3 is used to provide a constant pressure to the pressure control chamber 20 above the piston 26. The automatic constant pressure pump 3 can be operated on the LCD panel of the control box 8 or connected to a computer for control. A pressure sensor 7 is provided on the upper part of the automatic constant pressure pump 3 to detect the real-time pressure of the automatic constant pressure pump 3.

[0100] Further, if Figure 2 As shown, a right-angle needle valve 31 is provided on the automatic constant pressure pump 3 , and the right-angle needle valve 31 is used for exhausting the automatic constant pressure pump 3 .

[0101] When the automatic constant pressure pump 3 is in use, the right-angle needle valve 31 must be opened first to exhaust the gas in the cavity under the liquid pressure, otherwise the automatic constant pressure pump 3 will be affected in providing a constant pressure. After the gas is exhausted, the right-angle needle valve 31 is closed.

[0102] Furthermore, the automatic constant pressure pump 3 is controlled by a PLC data acquisition system, with a maximum working pressure of 105 MPa, a displacement range of 0.001 to 42 ml / min, a constant pressure accuracy of ±0.1 MPa, a tracking accuracy of ±0.1 MPa, a pressure tracking speed of 3 MPa / s, and an ambient temperature of 0°C to 50°C.

[0103] The operating process of the confining pressure control device of the present invention when combined with a simulation experiment (controlled pressure system) requiring confining pressure is as follows: open the water pump (existing technology) external to the controlled pressure system, wait for the liquid flow to stabilize and the liquid enters the control valve 4, start the automatic constant pressure pump 3, open the right-angle needle valve 31 on the automatic constant pressure pump 3 and close it after the gas is emptied, and the entire system can work normally.

[0104] Further, if Figure 2 As shown, the confining pressure control device of the present invention further comprises a frame 9 , on which a support plate 91 is arranged, and on which a fine filter 1 , a high-precision back pressure device 2 and an automatic constant pressure pump 3 are arranged.

[0105] The wall of the fine filter 1 is provided with supporting feet, which are connected to the frame 9 by threads; the lower seat 23 of the high-precision back pressure device 2 is placed on the support plate 91 so that the high-precision back pressure device 2 can cooperate with the fine filter 1; the control box 8 for controlling the automatic constant pressure pump 3 is also installed on the frame 9.

[0106] Each component is processed independently, with low manufacturing cost, and is uniformly assembled on the frame 9. The structure is safe and reliable, and two components cooperate with each other, which is convenient for assembly and disassembly, avoiding the extra cost caused by the disassembly of the overall structure. The adjustment is quick and convenient, and the maintenance is easy.

[0107] The invention has a reliable structure and strong sealing performance. Sealing rings are installed at key design positions of the device (matching positions between various parts) to ensure sealing performance, and a higher confining pressure can be achieved.

[0108] The present invention also provides an operating method of a confining pressure control device as follows:

[0109] The pressure-controlled liquid of the pressure-controlled system is filtered by the fine filter 1 and flows into the communication circuit 21. One path of the liquid flows to the fifth communication hole of the lower seat 23, and the other path of the liquid flows to the front end liquid injection cavity of the inner concave chamber of the valve body 22 (below the piston 26, generally directly injected into the inner groove 261 of the piston 26). The pressure at the bottom of the piston 26 is equal to the front end pressure of the device, that is, the pressure of the pressure-controlled system;

[0110] When the pressure at the bottom of the piston 26 is greater than the pressure applied to the pressure control chamber 20 by the automatic constant pressure pump 3, the piston 26 is pushed upward and drives the valve needle 27 to move upward, so that the outlet area of ​​the balanced liquid outlet channel increases, that is, the opening between the valve core 24 and the valve needle 27 increases, the high-precision back pressure device 2 releases pressure, and the front end pressure decreases;

[0111] When the pressure at the bottom of the piston 26 is less than the pressure applied to the pressure control chamber 20 by the automatic constant pressure pump 3, the piston 26 is pushed downward to drive the valve needle 27 downward, so that the outlet area of ​​the balanced liquid outlet channel is reduced, that is, the opening between the valve core 24 and the valve needle 27 is reduced, the high-precision back pressure device 2 is pressurized, and the front end pressure is increased;

[0112] After the front-end pressure is increased or decreased and adjusted, it will reach a pressure equal to that of the automatic constant pressure pump 3. At this time, the upper and lower pressures of the piston 26 are equal, that is, the pressures of the pressure control chamber 20 and the front-end liquid injection chamber are equal, thereby stopping the movement, and the opening between the valve core 24 and the valve needle 27 remains unchanged, and the front-end pressure is equal to the pressure of the automatic constant pressure pump 3.

[0113] Once the front-end pressure (pressure of the controlled pressure system) changes, the piston 26 will continuously repeat the above steps under the action of the upper and lower pressure differences, so that the pressure below the piston 26 (the front-end liquid injection chamber), that is, the front-end pressure of the system, is equal to the pressure of the automatic constant pressure pump 3, thereby achieving a dynamic balance of the confining pressure.

[0114] As described above, the confining pressure control device and the operating method thereof of the present invention have the following beneficial effects:

[0115] The fine filter of the present invention can filter the liquid to be pressure-controlled entering the device, so that solid impurity particles are settled to avoid entering the subsequent structure and causing wear;

[0116] The high-precision back pressure device of the present invention controls the opening of the balanced liquid outlet channel through the sliding of a piston-type hydraulic balance structure, and the automatic constant pressure pump provides a constant back pressure to the pressure control chamber above the hydraulic balance structure, thereby realizing pressure regulation, and the pressure regulation is automated, so that human-machine separation is achieved and safety is guaranteed; the surrounding pressure is regulated by adjusting the pressure of the automatic constant pressure pump, and the surrounding pressure is larger and more stable, which satisfies a wider range of simulated surrounding pressure; the high-precision back pressure device is not a high-precision hydraulic device, and is insensitive to liquid viscosity, so that the pressure stability will not be affected by liquid viscosity; compared with a hydraulically controlled surrounding pressure control system, the cost is lower, the control principle is simpler, and the surrounding pressure is more stable;

[0117] The invention has a simple overall structure, good sealing performance, quick and convenient adjustment and easy maintenance.

[0118] The above description is only an illustrative embodiment of the present invention and is not intended to limit the scope of the present invention. Any equivalent changes and modifications made by any person skilled in the art without departing from the concept and principle of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A confining pressure control device, characterized in that: include, Fine filter, used to filter the liquid to be pressure controlled to allow solid impurity particles to settle; A high-precision back-pressure device comprises a back-pressure body, wherein an inner concave chamber and a balanced liquid outlet channel are arranged in the back-pressure body, wherein a piston-type hydraulic balance structure can be slidably arranged in the inner concave chamber and the balanced liquid outlet channel, wherein the portion of the inner concave chamber located above the hydraulic balance structure constitutes a pressure control chamber; the portion of the inner concave chamber located below the hydraulic balance structure constitutes a front-end liquid injection chamber; the back-pressure body is connected with a connecting circuit, wherein a first end of the connecting circuit is connected with the front-end liquid injection chamber, and a second end of the connecting circuit is connected with the balanced liquid outlet channel, wherein a back-pressure body inlet connected with the fine filter is arranged on the connecting circuit; an automatic constant pressure pump is connected with the pressure control chamber, wherein the automatic constant pressure pump applies a constant pressure to the pressure control chamber, and the hydraulic balance structure slides under the pressure difference between the pressure control chamber and the front-end liquid injection chamber to control the opening of the balanced liquid outlet channel.

2. The confining pressure control device according to claim 1, characterized in that: The back pressure body comprises a valve body, the lower part of the valve body is sealed and connected to the lower seat, the top end of the valve body is downwardly provided with the inner concave chamber, and the bottom end of the inner concave chamber is downwardly provided with a first communication hole; A valve core cavity is upwardly arranged at the bottom end of the lower seat, a second communication hole connected to the first communication hole is upwardly penetrated through the top end of the valve core cavity, a valve core is arranged in the valve core cavity, a third communication hole is penetrated through the valve core, the bottom end of the valve core cavity is connected to the lower joint, and a fourth communication hole is penetrated through the lower joint; A fifth communicating hole penetrating to the second communicating hole is provided on the side wall of the lower seat, the fifth communicating hole is connected to the second end of the communicating loop, and the first communicating hole, the second communicating hole, the third communicating hole, the fourth communicating hole and the fifth communicating hole are connected to form the balanced liquid outlet channel; The hydraulic balance structure includes a piston slidably disposed in the inner concave chamber, the bottom end of the piston is connected to a valve needle, the valve needle is slidably disposed in the first connecting hole and the second connecting hole, the valve needle penetrates the valve body and the lower seat; and the bottom end of the valve needle can block the third connecting hole of the valve core, or can slide away from the third connecting hole to change the opening of the balanced liquid outlet channel.

3. The confining pressure control device according to claim 2, characterized in that: The communication loop includes a U-shaped tube, and two straight tube parts of the U-shaped tube are arranged horizontally; the first end of the U-shaped tube is connected to the bottom end of the concave chamber, and the second end of the U-shaped tube is connected to the fifth communication hole and the fine filter.

4. The confining pressure control device according to claim 3, characterized in that: A three-way joint is provided at the second end of the U-shaped tube, a first interface of the three-way joint is connected to the U-shaped tube, a second interface of the three-way joint constitutes the inlet of the return pressure body, and a third interface of the three-way joint is connected to the fifth connecting hole through a straight joint.

5. The confining pressure control device according to claim 4, characterized in that: A sixth communicating hole is disposed in the valve body, a first end of the sixth communicating hole is communicated with a first end of the U-shaped tube, and a second end of the sixth communicating hole is communicated with a bottom end of the concave chamber.

6. The confining pressure control device according to claim 5, characterized in that: The first end of the U-shaped tube is sealed and connected to the sixth connecting hole through a plug and a pressure cap, and the second end of the U-shaped tube is connected to the first interface of the three-way joint through a plug and a pressure cap.

7. The confining pressure control device according to claim 6, characterized in that: An inner groove is arranged at the bottom end of the piston, and the second end of the sixth communicating hole is arranged corresponding to the inner groove.

8. The confining pressure control device according to claim 2, characterized in that: A pressure pad is arranged between the valve core and the lower joint.

9. The confining pressure control device according to claim 2, characterized in that: The maximum working pressure of the high-precision back pressure device is 105MPa, the confining pressure stability accuracy is ±1MPa, the working environment temperature is 0-50°C, and the maximum allowable flow rate is 30L / min.

10. The confining pressure control device according to claim 2, characterized in that: The fine filter comprises a cylinder body, a filter center hole is provided through the cylinder body, a filter liquid inlet is provided on the side wall of the cylinder body, two ends of the filter center hole are respectively sealed and connected to a first cover body and a second cover body, a hollow filter element is axially provided in the filter center hole, and two ends of the filter element are mounted on the first cover body and the second cover body; a filter annulus is formed between the outer wall of the filter element and the side wall of the filter center hole, and the filter liquid inlet is connected with the filter annulus; a cover body through hole connected with the inner cavity of the filter element is provided on the second cover body, and the cover body through hole forms a filter liquid outlet, and the liquid to be pressure controlled passes through the filter liquid inlet and the filter annulus and is filtered by the filter element.

11. The confining pressure control device according to claim 10, characterized in that: The maximum working pressure of the fine filter is 105 MPa, the filtering accuracy is 3 μm, and the maximum allowable flow rate is 30 L / min.

12. The confining pressure control device according to claim 10, characterized in that: The liquid inlet of the filter is connected to a control valve, and the inlet of the control valve is connected to a four-way joint.

13. The confining pressure control device according to claim 2, characterized in that: The automatic constant pressure pump is connected to a pressure sensor, and the pressure sensor is used to detect the real-time pressure of the automatic constant pressure pump.

14. The confining pressure control device according to claim 13, characterized in that: The automatic constant pressure pump is electrically connected to the control cabinet.

15. The confining pressure control device according to claim 13, characterized in that: A right-angle needle valve is arranged on the automatic constant pressure pump, and the right-angle needle valve is used for exhausting the automatic constant pressure pump.

16. The confining pressure control device according to claim 13, characterized in that: The automatic constant pressure pump is controlled by a PLC data acquisition system, with a maximum working pressure of 105MPa, a displacement range of 0.001-42ml / min, a constant pressure accuracy of ±0.1MPa, a tracking accuracy of ±0.1MPa, a pressure tracking speed of 3MPa / s, and an ambient temperature of 0°C-50°C.

17. The confining pressure control device according to claim 2, characterized in that: It also includes a frame, on which a support plate is arranged, and on which the fine filter, the high-precision back pressure device and the automatic constant pressure pump are arranged.

18. An operating method of the confining pressure control device according to any one of claims 2 to 17, characterized in that: include: The pressure-controlled liquid of the controlled pressure system is filtered by a fine filter and flows into the connecting circuit of the high-precision back pressure device. One path of liquid flows to the fifth connecting hole of the lower seat, and the other path of liquid flows to the front liquid injection cavity below the piston in the concave chamber of the valve body. The pressure at the bottom of the piston is equal to the front pressure of the device. When the pressure at the bottom of the piston is greater than the pressure applied to the pressure control chamber by the automatic constant pressure pump, the piston is pushed upward and drives the valve needle to move upward, that is, the opening between the valve core and the valve needle increases, so that the outlet area of ​​the balanced liquid outlet channel increases, the high-precision back pressure device releases pressure, and the front end pressure decreases; When the pressure at the bottom of the piston is less than the pressure applied to the pressure control chamber by the automatic constant pressure pump, the piston is pushed downward to drive the valve needle downward, that is, the opening between the valve core and the valve needle is reduced, so that the outlet area of ​​the balanced liquid outlet channel is reduced, the high-precision back pressure device is pressurized, and the front end pressure is increased; After the front end pressure is increased or decreased and adjusted, it reaches the pressure equal to that of the automatic constant pressure pump, and the upper and lower pressures of the piston are equal and stop moving; When the front pressure changes, the piston repeats the above steps under the action of the upper and lower pressure difference, so that the pressure below the piston is equal to the pressure of the automatic constant pressure pump, achieving dynamic balance of the confining pressure.

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