Multifunctional rock test system and method under multi-field coupling condition

Abstract

The invention provides a multifunctional rock test system under a multi-field coupling condition, which is internally provided with a reaction cabin, a rock sample is placed in the reaction cabin, and the system is internally provided with an axial force loading control system, a confining pressure oil circulation system, a high-temperature heating and control system, an injection pump system and a temperature and strain measurement system. The subsystems are respectively in communication connection with the computer display and control system and are respectively used for controlling the pressure or temperature in the reaction cabin; the test method based on the system comprises the following steps: 1) processing a rock sample; 2) assembling a rock sample; 3) loading the rock sample into a reaction cabin; the method comprises the steps of (1) preparing a rock sample, (2) assembling a reaction cabin, (5) initializing a system and fixing the rock sample, (6) providing a confining pressure environment for the rock sample, (7) providing a high-temperature environment for the rock sample, (8) providing a triaxial high-pressure environment for the rock sample, (9) providing a chemical field and osmotic pressure environment for the rock sample, (10) providing water pressure for the rock sample and monitoring pressure, temperature and strain changes, (11) relieving pressure, cooling and recovering confining pressure oil, and (12) sorting and processing data.

Description

Technical Field

[0001] The invention relates to the technical field of geological testing, and in particular to a multifunctional rock testing system and method under multi-field coupling conditions. Background Art

[0002] In the fields of geological engineering, energy development, infrastructure construction, etc., as the basic component of the earth's crust, the accurate assessment of its physical and mechanical properties and hydraulic characteristics is directly related to the safety and economy of the project. In particular, with the efficient utilization of oil shale resources, the development of hot dry rock geothermal energy, and the continuous advancement of deep tunnels and large-scale mining projects, the need to understand and predict the behavior characteristics of rocks under complex environmental conditions is becoming increasingly urgent. These complex environmental conditions often involve multi-field coupling (THMC) such as heat (Temperature), water (Hydrology), mechanics (Mechanical), and chemistry (Chemistry). The interaction of these factors significantly affects the physical state, mechanical response, and fluid migration characteristics of rocks.

[0003] Traditional rock test systems focus on the independent study of a single or a few factors, ignoring the complexity of multi-field coupling effects in actual geological environments. For example, during the development of oil shale, the increase in temperature not only directly affects the strength and deformation characteristics of the rock, but also affects the permeability of the fluid by changing the internal pore structure of the rock, thereby affecting the efficiency of hydraulic fracturing; in hot dry rock geothermal systems, the chemical reaction between high-temperature and high-pressure water and rocks will significantly change the mechanical properties and seepage performance of the rocks; tunnels and mining projects often face stability problems under the coupling of multiple factors such as groundwater seepage, stress concentration and rock weathering. To this end, it is necessary to design a test system and method that can simulate multi-field coupling conditions and can conduct triaxial tests, permeability tests, hydraulic fracturing tests and coupling tests. Summary of the invention

[0004] The purpose of the present invention is to provide a multifunctional rock testing system and method under multi-field coupling conditions that simulates the physical and hydraulic properties of rocks under THMC conditions, simplifies test steps, improves test efficiency, and obtains accurate test results, and is applicable to a variety of rock samples.

[0005] In order to achieve the above object, the present invention is implemented by the following technical solutions: The multifunctional rock test system under multi-field coupling conditions is a test space, the test space has a built-in reaction chamber, and the rock sample is placed in the reaction chamber. The test space is equipped with an axial force loading control system, a confining pressure oil circulation system, a high-temperature heating and control system, an injection pump system, and a temperature and strain measurement system. Each system in the test space is respectively connected to a remote computer display and control system and is used to control the pressure or temperature conditions in the reaction chamber. The axial force loading control system controls the axial force column arranged at the bottom of the test space to move up and down through a servo hydraulic press to apply axial force to the rock sample; The confining pressure oil circulation system controls the confining pressure oil to enter and exit through the confining pressure oil inlet valve and confining pressure oil outlet valve arranged in the test space through a bidirectional electric pump, so as to inject confining pressure oil into the reaction chamber to provide a high-pressure environment for the rock sample; The high temperature heating and control system heats the confining pressure oil in the reaction chamber through the heating wires arranged on the inner wall of the test space, thereby providing a high temperature environment for the rock sample; The injection pump system pumps the fracturing fluid or chemical solution in the external fracturing fluid box or chemical solution box into the rock sample through the two-way valve of the reaction chamber, and the fracturing fluid or chemical solution after use flows into the liquid recovery tank through the outflow liquid high-pressure valve; The temperature and strain measurement system comprises a plurality of temperature probes, axial and radial strain measuring instruments arranged on the outer wall of the rock sample.

[0006] Furthermore, the upper and lower ends of the rock sample are respectively connected to an upper pad and a lower pad, the upper pad is located between the top wall of the reaction chamber and the upper end of the rock sample, and the lower pad is located between the bottom wall of the reaction chamber and the lower end of the rock sample. The outside of the rock sample is wrapped with a high-elastic rubber tube, and the upper and lower ends of the rubber tube are respectively tightly connected and fixed to the upper pad and the lower pad.

[0007] Furthermore, the upper pad is a triaxial test upper pad, which is composed of a fixed upper column and a pad body, and the fixed upper column is inserted into the top wall of the reaction chamber; the lower pad is a seepage-free and hydraulic fracturing-free lower pad, which is composed of a fixed lower column and a pad body, and the fixed lower column is inserted into the axial force column connected to the bottom wall of the reaction chamber.

[0008] Furthermore, the upper pad is a hydraulic fracturing test upper pad, which consists of an injection pipe and a pad body. The injection pipe runs through the central axis of the pad body, the upper end of the injection pipe is plugged into the top wall of the reaction chamber and is connected to the two-way valve of the reaction chamber through a pipeline, and the lower end of the injection pipe is plugged into the prefabricated drilled hole of the rock sample; the lower pad is a seepage or hydraulic fracturing lower pad, which consists of a seepage grid, a water collecting funnel, a pad body, a fixed outer pipe and a water outlet pipe. The upper end of the pad body is concave to form a water collecting funnel, a permeable grid is laid on the upper side of the water collecting funnel, the fixed outer pipe passes through the water outlet pipe, the fixed outer pipe and the water outlet pipe run through the pad body and the lower end thereof is connected to the outflowing liquid high-pressure valve through a pipeline.

[0009] Furthermore, the upper pad is an upper pad for seepage or seepage heat exchange test, which is composed of an inner liquid injection tube, an outer liquid injection tube, a permeable grid and a pad body. The inner liquid injection tube passes through the outer liquid injection tube, and the inner liquid injection tube and the outer liquid injection tube are plugged into the top wall of the reaction chamber and are connected to the two-way valve of the reaction chamber through a pipeline, and a permeable grid is arranged in the pad body; the lower pad is a lower pad for seepage or hydraulic fracturing, which is composed of a permeable grid, a water collecting funnel, a pad body, a fixed outer tube and a water outlet pipe, the upper end of the pad body is concave to form a water collecting funnel, a permeable grid is laid on the upper side of the water collecting funnel, the fixed outer tube passes through the water outlet pipe, the fixed outer tube and the water outlet pipe pass through the pad body and their lower ends are connected to the outflowing liquid high-pressure valve through a pipeline.

[0010] Furthermore, the upper pad is an upper pad for seepage and hydraulic fracturing tests, which consists of a fracturing fluid injection pipe, a chemical solution injection pipe, an external fixed pipe, a permeable grid, and a pad body. The fracturing fluid injection pipe and the chemical solution injection pipe are arranged side by side in the external fixed pipe and are respectively connected to the two-way valve of the reaction chamber through pipelines. The external fixed pipe runs through the pad body, and a permeable grid is arranged in the pad body; the lower pad is a lower pad for seepage or hydraulic fracturing, which consists of a permeable grid, a water collecting funnel, a pad body, a fixed outer pipe and a water outlet pipe. The upper end of the pad body is concave to form a water collecting funnel, a permeable grid is laid on the upper side of the water collecting funnel, the outlet pipe is passed through the fixed outer pipe, the fixed outer pipe and the outlet pipe run through the pad body and their lower ends are connected to the outflowing liquid high-pressure valve through pipelines.

[0011] Furthermore, a plurality of pulleys are provided on both sides of the reaction chamber base, and slideways are provided on both sides of the bottom wall of the test space, respectively. The pulleys can slide in the slideways so as to push the reaction chamber in or out.

[0012] Furthermore, condensation pipes are arranged on both sides of the bottom of the test space, and the condensation pipes are connected to the external cooling system. The confining pressure oil flows into the condensation pipes through the reaction cabin oil outlet valve, is cooled, and then is recovered to the confining pressure oil circulation system through the confining pressure oil outlet valve.

[0013] The multifunctional rock test method under multi-field coupling conditions includes the following steps: Step S1) Processing rock samples Use a rock sample cutter to process the rock sample into a cylindrical shape, set prefabricated fractures or simulated faults as needed, and drill a certain depth into the axis of the rock sample to form a water guide hole; Step S2) Assembling rock samples Clamp the rock sample between the upper pad for seepage and hydraulic fracturing test and the lower pad for seepage or hydraulic fracturing, insert it into a high-elastic rubber tube and seal the two ends of the rubber tube tightly to the upper and lower pads, install and adjust several temperature probes, axial and radial strain gauges; Step S3) Loading rock samples into the reaction chamber Unlock the inner lock handle to open the test space switch door, push out the reaction chamber through the pulley and slideway, and install the high-elastic rubber cylinder containing the rock sample and the upper and lower pads into the reaction chamber; Step S4) Assembling the reaction chamber Push the reaction chamber into the test space, connect the upper end of the fracturing fluid injection pipe to the two-way valve of the reaction chamber through a pipeline, insert the lower end of the pipe into the pre-drilled rock sample, connect the upper end of the chemical solution injection pipe to the two-way valve of the reaction chamber through a pipeline, and insert the fixed outer pipe of the lower pad into the fixed hole of the axial force column to fix the rock sample; Step S5) Initialize the system and fix the rock sample Turn on the remote computer display and control system, start the servo hydraulic press, control the servo hydraulic press through the computer display and control system to push the axial force column upward and monitor the pressure through the connected pressure sensor, first apply a small axial pressure to the rock sample to play a fixing role; Step S6) Providing a confining pressure environment to the rock sample Close the two-way valve and the oil outlet valve of the reaction chamber, open the confining pressure oil inlet valve, inject the confining pressure oil into the reaction chamber through the confining pressure oil circulation system, and control the confining pressure oil volume through the computer display and control system to provide a confining pressure environment for the rock sample; Step S7) Providing a high temperature environment to the rock sample The high temperature heating and control system controls the heating wire to heat the confining pressure oil in the reaction chamber, providing a high temperature environment for the rock sample; Step S8) Providing a triaxial high pressure environment to the rock sample The servo hydraulic press is controlled by the computer display and control system to adjust the axial pressure, and combined with the confining pressure provided by the confining pressure oil, a triaxial high-pressure environment is provided for the rock sample; Step S9) Providing a chemical field and osmotic pressure environment to the rock sample Open the injection liquid high-pressure two-way valve, the reaction chamber two-way valve and the outflow liquid high-pressure valve, and pump the prepared chemical solution stored in the chemical solution box into the chemical solution injection pipe through the injection pump system, and then penetrate downward into the sample through the permeable grid to form a uniform osmotic pressure, thereby providing a chemical field environment and an osmotic pressure environment for the rock sample; Step S10) Provide water pressure to the rock sample and monitor changes in pressure, temperature, and strain The fracturing fluid stored in the fracturing fluid box is injected into the fracturing fluid injection pipe through the injection pump system to apply water pressure to the rock sample until it is destroyed. The liquid flowing through the rock sample will be collected by the water collecting funnel in the pad body and discharged to the liquid recovery tank through the outlet pipe; the injection pressure, temperature, and strain changes in this process are recorded and transmitted to the computer display and control system for real-time display and storage; Step S11) Pressure relief, cooling and recovery of confining pressure oil After the test is completed, close the two-way valve of the reaction chamber, open the oil outlet valve of the reaction chamber and the confining pressure oil outlet valve, unload the confining pressure to normal pressure through the confining pressure oil circulation system, and then suck the high-temperature hydraulic oil into the condensation pipeline for cooling and then recover it to the oil tank of the confining pressure oil circulation system; Step S12) Arrange and process data The computer display and control system controls the servo hydraulic press to lower the reaction cabin, open the test space switch door, push the reaction cabin out through the pulley and slide, take out the rock sample, process the data, and conduct the next test.

[0014] Furthermore, if the rock sample does not require water pressure testing, step S10 is omitted; if the rock sample does not require osmotic pressure testing, step S9 is omitted; if the rock sample is only subjected to triaxial pressure testing, steps S9) and S10) are omitted.

[0015] Compared with the prior art, the present invention has the following advantages: The multifunctional rock testing system and method under multi-field coupling conditions of the present invention simulate the physical and hydraulic properties of rocks under THMC conditions, simplify the test steps, improve the test efficiency, obtain accurate test results, and are applicable to a variety of rock samples. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic cross-sectional view of the system of the present invention.

[0017] Figure 2 It is a structural schematic diagram of the upper pad of the triaxial test of the present invention.

[0018] Figure 3 It is a structural schematic diagram of the hydraulic fracturing test upper pad of the present invention.

[0019] Figure 4 It is a structural schematic diagram of a pad on a seepage or seepage heat exchange test of the present invention.

[0020] Figure 5 It is a structural schematic diagram of the upper pad for seepage and hydraulic fracturing test of the present invention.

[0021] Figure 6 It is a structural schematic diagram of the cushion block under the non-seepage and non-hydraulic fracturing test of the present invention.

[0022] Figure 7 It is a structural schematic diagram of a cushion block with seepage or hydraulic fracturing according to the present invention.

[0023] Figure 8 It is a schematic diagram of the positional relationship between the reaction chamber and the test system of the present invention.

[0024] Fig. 9It is a schematic diagram of the pulley structure of the reaction chamber of the present invention.

[0025] Fig.10 It is a schematic diagram of the reaction chamber slide structure of the present invention.

[0026] Figure numerals: 1. Liquid recovery tank, 2. Axial force loading control system, 3. Confining pressure oil circulation system, 4. Computer display and control system, 5. High temperature heating and control system, 6. Injection pump system, 7. Fracturing fluid tank, 8. Chemical solution tank, 9. Temperature and strain measurement system, 10. Injection liquid high pressure two-way valve, 11. Reaction chamber two-way valve, 12. Upper pad, 13. Left wall of reaction chamber, 14. Temperature probe, 15. Reaction chamber, 16. Axial and radial strain gauge, 17. Heating wire, 18. Rock sample, 19. Rubber cylinder, 20. Reaction chamber oil outlet valve, 21. Pulley, 22. Slide, 23. Condensation pipeline, 24. Lower pad, 25. Outflow liquid high pressure valve, 26. Test space, 27. Servo hydraulic press, 28. Confining pressure oil outlet valve, 29. Right wall of reaction chamber, 30. Confining pressure oil inlet valve, 121. Upper pad for triaxial test, 1211. Fixed upper column, 1212. Pad body 1, 122. Upper pad for hydraulic fracturing test, 1221. Water injection pipe, 1222. Pad body 2, 123. Upper pad for seepage or seepage heat exchange test, 1231. Injection inner pipe, 1232. Injection pipe outer wall, 1233. Permeable grid 1, 1234. Pad body 3, 124. Upper pad for seepage and hydraulic fracturing test, 1241. Fracturing fluid injection pipe, 1242. Chemical solution Liquid injection pipe, 1243. Infiltration grid II, 1244. Pad body IV, 1245. Fixed outer pipe, 241. Pad without seepage and without hydraulic fracturing, 2411. Pad body V, 2412. Fixed lower column, 242. Pad with seepage or hydraulic fracturing, 2421. Infiltration grid III, 2422. Water collecting funnel, 2423. Pad body VI, 2424. Fixed outer pipe II, 2425. Water outlet pipe, 211. Pulley bracket, 212 Concave pulley, 221. Slide bracket, 222. Convex slide, 31. Front wall of test space, 32. Test space switch door, 33. Internal locking handle. DETAILED DESCRIPTION

[0027] The embodiments of the present invention are described in further detail below in conjunction with the accompanying drawings.

[0028] like Figure 1As shown, the multifunctional rock test system under multi-field coupling conditions is a test space 26, the test space 26 has a built-in reaction chamber 15, the reaction chamber 15 includes a left wall 13 and a right wall 29 of the reaction chamber, and a rock sample 18 is placed in the reaction chamber 15. The test space 26 is equipped with an axial force loading control system 2, a confining pressure oil circulation system 3, a high temperature heating and control system 5, an injection pump system 6, and a temperature and strain measurement system 9. Each system in the test space 26 is respectively connected to the remote computer display and control system 4 for communication and is used to control the pressure or temperature conditions in the reaction chamber 15; the axial force loading control system 2 controls the axial force column set at the bottom of the test space 26 to move up and down through a servo hydraulic press 27 to apply axial force to the rock sample 18; the confining pressure oil circulation system 3 controls the confining pressure oil through a bidirectional electric pump The confining pressure oil inlet valve 30 and the confining pressure oil outlet valve 28 provided in the test space 26 are used to inject confining pressure oil into the reaction chamber 15 to provide a high-pressure environment for the rock sample 18; the high-temperature heating and control system 5 heats the confining pressure oil in the reaction chamber 15 through the heating wire 17 provided on the inner wall of the test space 26, thereby providing a high-temperature environment for the rock sample 18; the injection pump system 6 pumps the fracturing fluid (clean water, supercritical carbon dioxide, etc.) or chemical solution in the external fracturing fluid box 7 and the chemical solution box 8 into the rock sample through the reaction chamber two-way valve 11, and the fracturing fluid or chemical solution after use flows into the liquid recovery tank 1 through the outflow liquid high-pressure valve 25; the temperature and strain measurement system 9 includes a plurality of temperature probes 14 and axial and radial strain gauges 16 placed on the outer wall of the rock sample 18.

[0029] The upper and lower ends of the rock sample 18 are respectively connected to the upper pad 12 and the lower pad 24, the upper pad 12 is located between the top wall of the reaction chamber 15 and the upper end of the rock sample 18, and the lower pad 24 is located between the bottom wall of the reaction chamber 15 and the lower end of the rock sample 18. The rock sample 18 is wrapped with a high-elastic rubber tube 19, and the upper and lower ends of the rubber tube 19 are respectively tightly connected and fixed to the upper pad 12 and the lower pad 24.

[0030] The upper pad 12 is divided into four types, namely, a triaxial test upper pad 121, a hydraulic fracturing test upper pad 122, a seepage or seepage heat exchange test upper pad 123, and a seepage and hydraulic fracturing test upper pad 124. Figure 2 As shown, the triaxial test upper pad 121 is composed of a fixed upper column 1211 and a pad body 1212, and the fixed upper column 1211 is plugged into the top wall of the reaction chamber 15. Figure 3 As shown, the hydraulic fracturing test upper pad 122 is composed of a water injection pipe 1221 and a pad body 1222. The water injection pipe 1221 runs through the central axis of the pad body 1222. The upper end of the water injection pipe 1221 is plugged into the top wall of the reaction chamber 15 and connected to the reaction chamber two-way valve 11 through a pipeline. The lower end of the water injection pipe 1221 is plugged into the prefabricated drilled hole of the rock sample 18. Figure 4 As shown, the upper pad 123 for the seepage or seepage heat exchange test is composed of an inner liquid injection tube 1231, an outer liquid injection tube 1232, a permeable grid 1233, and a pad body 1234. The inner liquid injection tube 1231 passes through the outer liquid injection tube 1232. The inner liquid injection tube 1231 and the outer liquid injection tube 1232 are plugged into the top wall of the reaction chamber 15 and connected to the reaction chamber two-way valve 11 through a pipeline. The pad body 1234 is provided with a permeable grid 1233. Figure 5 As shown, the seepage and hydraulic fracturing test upper pad 124 is composed of a fracturing fluid injection pipe 1241, a chemical solution injection pipe 1242, a fixed outer pipe 1245, a second permeable grid 1243, and a pad body 1244. The fracturing fluid injection pipe 1241 and the chemical solution injection pipe 1242 are arranged side by side in the fixed outer pipe 1245 and are respectively connected to the reaction chamber two-way valve 11 through pipelines. The fixed outer pipe 1245 passes through the pad body 1244, and a second permeable grid 1243 is arranged in the pad body 1244.

[0031] The lower pad 24 is divided into two types, namely, a lower pad 241 without seepage and hydraulic fracturing, and a lower pad 242 with seepage or hydraulic fracturing. Figure 6 As shown, the non-seepage and non-hydraulic fracturing lower pad 241 is composed of a fixed lower column 2412 and a pad body 5 2411, and the fixed lower column 2412 is plugged into the axial force column connected to the bottom wall of the reaction chamber 15. Figure 7 As shown, the seepage or hydraulic fracturing lower pad 242 is composed of a permeable grid three 2421, a water collecting funnel 2422, a pad body six 2423, a fixed outer tube two 2424 and a water outlet pipe 2425. The upper end of the pad body six 2423 is concave to form a water collecting funnel 2422. The permeable grid three 2421 is laid on the upper side of the water collecting funnel 2422. The fixed outer tube two 2424 runs through the water outlet pipe 2425. The fixed outer tube two 2424 and the water outlet pipe 2425 run through the pad body six 2423 and their lower ends are connected to the outflowing liquid high-pressure valve 25 through a pipeline.

[0032] Condensation pipes 23 are arranged on both sides of the bottom of the test space 26, and the condensation pipes 23 are connected to the external cooling system. The confining pressure oil flows into the condensation pipes 23 through the reaction chamber oil outlet valve 20, and then is cooled and recovered to the confining pressure oil circulation system 3 through the confining pressure oil outlet valve 28.

[0033] like Figure 8 As shown, the front of the test space 26 is an openable test space front wall 31, on which a test space switch door 32 and an inner locking handle 33 are provided. Opening the test space switch door 32 can facilitate entry and exit of the reaction chamber 15.

[0034] like Fig. 9 , 10As shown, a plurality of pulleys 21 are provided on both sides of the base of the reaction chamber 15, preferably two on each side, a total of four, and slideways 22 are provided on both sides of the bottom wall of the test space 26, respectively. The pulley 21 can slide in the slideway 22 to push or push the reaction chamber 15. Specifically, the pulley 21 includes a pulley bracket 211 and a concave pulley 212, the pulley bracket 211 is connected and fixed to both sides of the bottom of the reaction chamber 15, the concave pulley 212 is axially connected to the pulley bracket 211, and a groove is provided in the middle of the concave pulley 212; the slideway 22 includes a slideway bracket 221 and a convex slideway 222, the slideway bracket 221 is connected and fixed to both sides of the bottom wall of the test space 26, and the convex slideway 222 is consistent with the concave pulley 212.

[0035] Preferably, the rock sample 18 is processed into a cylindrical sample. The sample for hydraulic fracturing needs to be pre-drilled, and the sample for seepage test or triaxial test can be pre-fabricated with cracks, joints, etc.

[0036] Example 1 Hydraulic fracturing and permeability pressure test of rock samples under THMC multi-field coupling conditions The multifunctional rock test method under multi-field coupling conditions includes the following steps: Step S1) Processing rock samples Use a rock sample cutter to process the rock sample into a cylindrical shape, set prefabricated fractures or simulated faults as needed, and drill a certain depth into the axis of the rock sample to form a water guide hole; Step S2) Assembling rock samples The rock sample 18 is clamped between the upper pad 124 for seepage and hydraulic fracturing test and the lower pad 242 for seepage or hydraulic fracturing, and is inserted into the high elastic rubber tube 19 and the two ends of the rubber tube 19 are tightly sealed to the upper and lower pads, and a number of temperature probes 14, axial and radial strain gauges 16 are installed and adjusted; Step S3) Loading rock samples into the reaction chamber Unlock the inner lock handle 33 to open the test space switch door 32, push the reaction chamber 15 out through the pulley 21 and the slideway 22, and install the high-elastic rubber tube 19 containing the rock sample 18 and the upper and lower pads into the reaction chamber 15; Step S4) Assembling the reaction chamber Push the reaction chamber 15 into the test space 26, connect the upper end of the fracturing fluid injection pipe 1241 to the reaction chamber two-way valve 11 through a pipeline, insert the lower end of the pipe into the pre-drilled rock sample 18, connect the upper end of the chemical solution injection pipe 1242 to the reaction chamber two-way valve 11 through a pipeline, and insert the fixed outer pipe of the lower pad 24 into the fixed hole of the axial force column to fix the rock sample 18; Step S5) Initialize the system and fix the rock sample Turn on the remote computer display and control system 4, start the servo hydraulic press 27, control the servo hydraulic press 27 through the computer display and control system 4 to push the axial force column to move upward, and monitor the pressure through the connected pressure sensor, first apply a small axial pressure to the rock sample 18 to play a fixing role; Step S6) Providing a confining pressure environment to the rock sample Close the reaction chamber two-way valve 11 and the reaction chamber oil outlet valve 20, open the confining pressure oil inlet valve 30, inject the confining pressure oil into the reaction chamber 15 through the confining pressure oil circulation system 3, and control the confining pressure oil volume through the computer display and control system 4 to provide a confining pressure environment for the rock sample 18; Step S7) Providing a high temperature environment to the rock sample The high temperature heating and control system 5 controls the heating wire 17 to heat the confining pressure oil in the reaction chamber 15, thereby providing a high temperature environment for the rock sample 18; Step S8) Providing a triaxial high pressure environment to the rock sample The servo hydraulic press 27 is controlled by the computer display and control system 4 to adjust the axial pressure, and combined with the confining pressure provided by the confining pressure oil, a triaxial high pressure environment is provided to the rock sample 18; Step S9) Providing a chemical field and osmotic pressure environment to the rock sample Open the high-pressure two-way valve 10 for injection liquid, the two-way valve 11 for reaction chamber and the high-pressure valve for outflow liquid 25, and pump the prepared chemical solution stored in the chemical solution box 8 into the chemical solution injection pipe 1242 through the injection pump system 6, and then penetrate downward into the sample through the second permeation grid 1243, forming a uniform permeation pressure, thereby providing a chemical field environment and an permeation pressure environment for the rock sample 18; Step S10) Provide water pressure to the rock sample and monitor changes in pressure, temperature, and strain The fracturing fluid stored in the fracturing fluid box 7 is injected into the fracturing fluid injection pipe 1241 through the injection pump system 6 to apply water pressure to the rock sample 18 until it is destroyed. The liquid flowing through the rock sample 18 will be collected by the water collecting funnel 2422 in the cushion block body 1244 and discharged to the liquid recovery tank 1 through the outlet pipe 2425; the injection pressure, temperature, and strain changes in this process are recorded and transmitted to the computer display and control system 4 for real-time display and storage; Step S11) Pressure relief, cooling and recovery of confining pressure oil After the test is completed, the reaction chamber two-way valve 11 is closed, the reaction chamber oil outlet valve 20 and the confining pressure oil outlet valve 28 are opened, the confining pressure is unloaded to normal pressure through the confining pressure oil circulation system 3, and the high-temperature hydraulic oil is sucked into the condensation pipeline 23 for cooling and then recovered into the oil tank of the confining pressure oil circulation system 3; Step S12) Arrange and process data The computer display and control system 4 controls the servo hydraulic machine 27 to lower the reaction chamber 15, open the door of the test space 26, push the reaction chamber 15 out through the pulley 21 and the slide 22, take out the rock sample 18, process the data, and conduct the next test.

[0037] Example 2 Rock seepage or seepage heat transfer test under THMC multi-field coupling conditions Based on Example 1, step S10 is omitted).

[0038] Example 3 Hydraulic fracturing test of rock samples under high temperature and high pressure conditions Based on Example 1, step S9 is omitted).

[0039] Example 4 Triaxial test of rock samples under THMC multi-field coupling conditions Based on Example 1, step S9) and step S10) are omitted.

[0040] The above description is only a preferred embodiment of the present invention. It should be pointed out that ordinary technicians in this technical field can make several improvements and modifications without departing from the concept of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. Multifunctional rock test system under multi-field coupling conditions, characterized by: A test space is provided with a reaction chamber, in which a rock sample is placed, and an axial force loading control system, a confining pressure oil circulation system, a high temperature heating and control system, an injection pump system, and a temperature and strain measurement system are provided in the test space. Each system provided in the test space is respectively connected to a remote computer display and control system for communication and is respectively used to control the pressure or temperature conditions in the reaction chamber; The axial force loading control system controls the axial force column arranged at the bottom of the test space to move up and down through a servo hydraulic press to apply axial force to the rock sample; The confining pressure oil circulation system controls the confining pressure oil to enter and exit through the confining pressure oil inlet valve and confining pressure oil outlet valve arranged in the test space through a bidirectional electric pump, so as to inject confining pressure oil into the reaction chamber to provide a high-pressure environment for the rock sample; The high temperature heating and control system heats the confining pressure oil in the reaction chamber through the heating wires arranged on the inner wall of the test space, thereby providing a high temperature environment for the rock sample; The injection pump system pumps the fracturing fluid or chemical solution in the external fracturing fluid box or chemical solution box into the rock sample through the two-way valve of the reaction chamber, and the fracturing fluid or chemical solution after use flows into the liquid recovery tank through the outflow liquid high-pressure valve; The temperature and strain measurement system comprises a plurality of temperature probes, axial and radial strain measuring instruments arranged on the outer wall of the rock sample.

2. The multifunctional rock testing system under multi-field coupling conditions according to claim 1 is characterized in that: The upper and lower ends of the rock sample are respectively connected to an upper pad and a lower pad, the upper pad is located between the top wall of the reaction chamber and the upper end of the rock sample, and the lower pad is located between the bottom wall of the reaction chamber and the lower end of the rock sample. The rock sample is wrapped with a high-elastic rubber tube, and the upper and lower ends of the rubber tube are respectively tightly connected and fixed to the upper pad and the lower pad.

3. The multifunctional rock testing system under multi-field coupling conditions according to claim 2 is characterized in that: The upper pad is a triaxial test upper pad, which is composed of a fixed upper column and a pad body, and the fixed upper column is inserted into the top wall of the reaction chamber; the lower pad is a seepage-free and hydraulic fracturing-free lower pad, which is composed of a fixed lower column and a pad body, and the fixed lower column is inserted into the axial force column connected to the bottom wall of the reaction chamber.

4. The multifunctional rock testing system under multi-field coupling conditions according to claim 2 is characterized in that: The upper pad is a hydraulic fracturing test upper pad, which consists of an injection pipe and a pad body. The injection pipe runs through the central axis of the pad body, the upper end of the injection pipe is plugged into the top wall of the reaction chamber and is connected to the two-way valve of the reaction chamber through a pipeline, and the lower end of the injection pipe is plugged into the prefabricated drilled hole of the rock sample; the lower pad is a seepage or hydraulic fracturing lower pad, which consists of a seepage grid, a water collecting funnel, a pad body, a fixed outer pipe and a water outlet pipe. The upper end of the pad body is concave to form a water collecting funnel, a seepage grid is laid on the upper side of the water collecting funnel, the fixed outer pipe passes through the water outlet pipe, the fixed outer pipe and the water outlet pipe run through the pad body, and the lower end thereof is connected to the outflowing liquid high-pressure valve through a pipeline.

5. The multifunctional rock testing system under multi-field coupling conditions according to claim 2 is characterized in that: The upper pad is an upper pad for seepage or seepage heat exchange test. The upper pad for seepage or seepage heat exchange test consists of an inner liquid injection tube, an outer liquid injection tube, a permeable grid, and a pad body. The inner liquid injection tube runs through the outer liquid injection tube. The inner liquid injection tube and the outer liquid injection tube are plugged into the top wall of the reaction chamber and are connected to the two-way valve of the reaction chamber through a pipeline. A permeable grid is arranged in the pad body; the lower pad is a lower pad for seepage or hydraulic fracturing. The lower pad for seepage or hydraulic fracturing consists of a permeable grid, a water collecting funnel, a pad body, a fixed outer tube and a water outlet pipe. The upper end of the pad body is concave to form a water collecting funnel. A permeable grid is laid on the upper side of the water collecting funnel. The outlet pipe runs through the fixed outer tube. The fixed outer tube and the outlet pipe run through the pad body and their lower ends are connected to the high-pressure valve of the outflowing liquid through a pipeline.

6. The multifunctional rock testing system under multi-field coupling conditions according to claim 2 is characterized in that: The upper pad is an upper pad for seepage and hydraulic fracturing tests. The upper pad for seepage and hydraulic fracturing tests consists of a fracturing fluid injection pipe, a chemical solution injection pipe, an external fixed pipe, a permeable grid, and a pad body. The fracturing fluid injection pipe and the chemical solution injection pipe are arranged side by side in the external fixed pipe and are respectively connected to the two-way valve of the reaction chamber through pipelines. The external fixed pipe runs through the pad body, and a permeable grid is arranged in the pad body; the lower pad is a lower pad for seepage or hydraulic fracturing. The lower pad for seepage or hydraulic fracturing consists of a permeable grid, a water collecting funnel, a pad body, a fixed outer pipe and a water outlet pipe. The upper end of the pad body is concave to form a water collecting funnel. A permeable grid is laid on the upper side of the water collecting funnel. The outlet pipe runs through the fixed outer pipe. The fixed outer pipe and the outlet pipe run through the pad body and their lower ends are connected to the high-pressure valve of the outflowing liquid through pipelines.

7. The multifunctional rock testing system under multi-field coupling conditions according to claim 3, 4, 5 or 6, characterized in that: A plurality of pulleys are arranged on both sides of the reaction chamber base, and slideways are arranged on both sides of the bottom wall of the test space. The pulleys can slide in the slideways so as to push the reaction chamber in or out.

8. The multifunctional rock testing system under multi-field coupling conditions according to claim 7 is characterized in that: Condensation pipes are arranged on both sides of the bottom of the test space, and the condensation pipes are connected to the external cooling system. The confining pressure oil flows into the condensation pipes through the reaction cabin oil outlet valve, is cooled, and then is recovered to the confining pressure oil circulation system through the confining pressure oil outlet valve.

9. Multifunctional rock test method under multi-field coupling conditions, characterized by The steps include: Step S1) Processing rock samples Use a rock sample cutter to process the rock sample into a cylindrical shape, set prefabricated fractures or simulated faults as needed, and drill a certain depth into the axis of the rock sample to form a water guide hole; Step S2) Assembling rock samples Clamp the rock sample between the upper pad for seepage and hydraulic fracturing test and the lower pad for seepage or hydraulic fracturing, insert it into a high-elastic rubber tube and seal the two ends of the rubber tube tightly to the upper and lower pads, install and adjust several temperature probes, axial and radial strain gauges; Step S3) Loading rock samples into the reaction chamber Unlock the inner lock handle to open the test space switch door, push out the reaction chamber through the pulley and slideway, and install the high-elastic rubber cylinder containing the rock sample and the upper and lower pads into the reaction chamber; Step S4) Assembling the reaction chamber Push the reaction chamber into the test space, connect the upper end of the fracturing fluid injection pipe to the two-way valve of the reaction chamber through a pipeline, insert the lower end of the pipe into the pre-drilled rock sample, connect the upper end of the chemical solution injection pipe to the two-way valve of the reaction chamber through a pipeline, and insert the fixed outer pipe of the lower pad into the fixed hole of the axial force column to fix the rock sample; Step S5) Initialize the system and fix the rock sample Turn on the remote computer display and control system, start the servo hydraulic press, control the servo hydraulic press through the computer display and control system to push the axial force column upward and monitor the pressure through the connected pressure sensor, first apply a small axial pressure to the rock sample to play a fixing role; Step S6) Providing a confining pressure environment to the rock sample Close the two-way valve and the oil outlet valve of the reaction chamber, open the confining pressure oil inlet valve, inject the confining pressure oil into the reaction chamber through the confining pressure oil circulation system, and control the confining pressure oil volume through the computer display and control system to provide a confining pressure environment for the rock sample; Step S7) Providing a high temperature environment to the rock sample The high temperature heating and control system controls the heating wire to heat the confining pressure oil in the reaction chamber, providing a high temperature environment for the rock sample; Step S8) Providing a triaxial high pressure environment to the rock sample The servo hydraulic press is controlled by the computer display and control system to adjust the axial pressure, and combined with the confining pressure provided by the confining pressure oil, a triaxial high-pressure environment is provided for the rock sample; Step S9) Providing a chemical field and osmotic pressure environment to the rock sample Open the injection liquid high-pressure two-way valve, the reaction chamber two-way valve and the outflow liquid high-pressure valve, and pump the prepared chemical solution stored in the chemical solution box into the chemical solution injection pipe through the injection pump system, and then penetrate downward into the sample through the permeable grid to form a uniform osmotic pressure, thereby providing a chemical field environment and an osmotic pressure environment for the rock sample; Step S10) Provide water pressure to the rock sample and monitor changes in pressure, temperature, and strain The fracturing fluid stored in the fracturing fluid box is injected into the fracturing fluid injection pipe through the injection pump system to apply water pressure to the rock sample until it is destroyed. The liquid flowing through the rock sample will be collected by the water collecting funnel in the pad body and discharged to the liquid recovery tank through the outlet pipe; the injection pressure, temperature, and strain changes in this process are recorded and transmitted to the computer display and control system for real-time display and storage; Step S11) Pressure relief, cooling and recovery of confining pressure oil After the test is completed, close the two-way valve of the reaction chamber, open the oil outlet valve of the reaction chamber and the confining pressure oil outlet valve, unload the confining pressure to normal pressure through the confining pressure oil circulation system, and then suck the high-temperature hydraulic oil into the condensation pipeline for cooling and then recover it to the oil tank of the confining pressure oil circulation system; Step S12) Arrange and process data The computer display and control system controls the servo hydraulic press to lower the reaction cabin, open the test space switch door, push the reaction cabin out through the pulley and slide, take out the rock sample, process the data, and conduct the next test.

10. The multifunctional rock testing method under multi-field coupling conditions according to claim 9, characterized in that: If the rock sample does not require water pressure testing, step S10 is omitted; if the rock sample does not require osmotic pressure testing, step S9 is omitted; if the rock sample is only subjected to triaxial pressure testing, steps S9) and S10) are omitted.

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