CN116429588A - Coal rock mass fracturing modification and effect evaluation test system and method thereof - Google Patents
Coal rock mass fracturing modification and effect evaluation test system and method thereof Download PDFInfo
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
- G01N3/10—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces generated by pneumatic or hydraulic pressure
- G01N3/12—Pressure testing
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume, or surface-area of porous materials
- G01N15/08—Investigating permeability, pore-volume, or surface area of porous materials
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume, or surface-area of porous materials
- G01N15/08—Investigating permeability, pore-volume, or surface area of porous materials
- G01N15/088—Investigating volume, surface area, size or distribution of pores; Porosimetry
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N7/00—Analysing materials by measuring the pressure or volume of a gas or vapour
- G01N7/02—Analysing materials by measuring the pressure or volume of a gas or vapour by absorption, adsorption, or combustion of components and measurement of the change in pressure or volume of the remainder
- G01N7/04—Analysing materials by measuring the pressure or volume of a gas or vapour by absorption, adsorption, or combustion of components and measurement of the change in pressure or volume of the remainder by absorption or adsorption alone
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/10—Geothermal energy
Abstract
The invention relates to the technical field of coal seam fracturing and permeability improvement, in particular to a coal rock mass fracturing modification and effect evaluation test system and method. The device comprises a fracturing modification system, an air injection evaluation system, a back pressure monitoring system, a hydraulic servo control system, a vacuum system and a data acquisition and control system, wherein a loading cavity of a cube cavity is arranged in the center of a true triaxial loading system, loading push rods penetrate through the centers of six surfaces of the loading cavity, the outer ends of the loading push rods are connected with a hydraulic cylinder body, the inner ends of the loading push rods are connected with loading pressing plates positioned in the loading cavity, and the loading push rods are respectively pressed on six sides of a sample; an L-shaped pipeline cavity hole is arranged in the loading push rod, an inner hole is arranged in the center of an inner end head of the loading push rod, an outer hole is arranged on the side face near the outer end head of the loading push rod, a communication conduit is arranged in the pipeline cavity hole, and the communication conduits in three loading push rods in the six faces are respectively used for connecting a fracturing modification system, an air injection evaluation system, a back pressure monitoring system and a vacuum system.
Description
Technical Field
The invention relates to the technical field of coal seam fracturing and permeability improvement, in particular to a coal rock mass fracturing modification and effect evaluation test system and method.
Background
In recent years, along with rapid development of fracturing equipment and technology, the fracturing technology has been widely applied to the fields of mining, hydraulic and hydroelectric engineering, oil and gas reservoir mining, geothermal mining and the like. The fracturing technology is one of the most effective technical means for reservoir reconstruction, and particularly has wider application in hydraulic fracturing, liquid nitrogen fracturing and carbon dioxide fracturing. In mining, the fracturing technology not only can be used for improving the surrounding rock structure and mechanical property of the coal bed, weakening the hard roof of the coal bed to realize pressure relief and impact prevention, but also can be used for permeability improvement of a low-permeability high-gas coal bed, improving the permeability and the flow conductivity of the coal bed, realizing high-efficiency mining of the coal bed gas, and avoiding coal and gas outburst and other coal rock mass dynamic disasters. On one hand, the coal bed fracturing can be used for manufacturing a large number of artificial cracks in the coal bed to form a reservoir crack network so as to improve the permeability of the coal bed and further improve the extraction efficiency of coal bed gas; on the other hand, the fracturing medium remained in the coal bed can also have physical and chemical action with the coal body to change the pore structure and the surface property of the coal body, thereby affecting the physical property of the coal body and the adsorption, desorption, diffusion and seepage properties of the coal body to different degrees.
In order to study the fracturing and seepage characteristics of the coal seam, researchers at home and abroad research and study a plurality of related devices and perform related experimental study, such as: CN110426286a "a true triaxial fracturing seepage continuous test system and method", CN111366472A "a true triaxial hydraulic fracturing physical simulation device and method for variable core size", CN209542309U "a large-size true triaxial hydraulic fracturing simulation test device", CN113418852A "an ultrasonic pulse fracturing gas-containing coal seepage test device and method", CN104655495A "a coal rock high-temperature high-pressure true triaxial fracturing seepage test device and test method". However, the fracturing seepage test system is mainly concentrated on the aspects of simulating crack expansion characteristics, seepage characteristics and the like under different physical fields and different medium fracturing, can not perform comprehensive and dynamic research on aspects of coal seam fracturing modification, seepage, adsorption and desorption, mechanical characteristics and the like under in-situ conditions (true triaxial stress, temperature, water content, gas pressure), and particularly can not consider the influence on the anisotropy (in the three directions of a sample X, Y, Z) and mechanical characteristics of the fracturing medium and the coal body after the physical and chemical modification, and meanwhile, a test method for comprehensively and dynamically evaluating the effect of the fracturing modified coal body of different mediums is lacked.
Disclosure of Invention
The invention aims to overcome the defects of the conventional fracturing seepage test device and fracturing effect evaluation method, and provides a fracturing modification and effect evaluation test system and method for coal and rock mass, which can be used for testing and researching the mechanical property, adsorption and desorption properties and anisotropic seepage properties of the coal and rock mass under different fracturing conditions, and can fully consider the influence of fracturing medium on the physical and chemical modification of the coal and rock mass and comprehensively and dynamically evaluate the fracturing modification effect of the coal and rock mass.
The invention adopts the following technical scheme: the utility model provides a coal rock mass fracturing modification and effect evaluation test system thereof, includes fracturing modification system, gas injection evaluation system, back pressure monitoring system, hydraulic servo control system, vacuum system and data acquisition and control system integration, and true triaxial loading system central point puts and is provided with the loading cavity of cube cavity, and the center of six faces of loading cavity wears loading push rod, and the outer end of loading push rod is connected with hydraulic cylinder body, and the inner end of loading push rod links to each other with the loading clamp plate that is located loading cavity, the loading clamp plate totally six, presses respectively on six sides of sample;
the loading pressing plate is provided with a thermocouple heating rod which is integrally controlled by a data acquisition and control system;
A fracturing hole is drilled in the center of one side surface of the sample;
a push rod sealing assembly is arranged at the sliding connection part of the loading push rod and the loading chamber;
an L-shaped pipeline cavity hole is formed in the loading push rod, an inner hole of the L-shaped pipeline cavity hole is positioned in the center of an inner end head of the loading push rod, an outer hole of the L-shaped pipeline cavity hole is positioned on the side face near the outer end head of the loading push rod, a communication conduit is arranged in the pipeline cavity hole, and the communication conduits in three loading push rods in the six sides are respectively used for connecting a fracturing modification system, an air injection evaluation system, a back pressure monitoring system and a vacuum system;
wherein the fracturing modification system provides different fracturing media for the test sample;
the gas injection evaluation system injects gases under different gas pressures into the sample;
the back pressure monitoring system is used for sucking out gas in the sample;
the vacuum system vacuumizes the loading chamber;
the data acquisition and control system is integrated to monitor and control the true triaxial loading system, the fracturing modification system, the gas injection evaluation system, the back pressure monitoring system, the hydraulic servo control system and the vacuum system through sensors respectively;
and the hydraulic servo control system injects or outputs hydraulic oil into the true triaxial loading system according to the test requirement.
In some embodiments, pipeline insertion holes are formed in the centers of the loading pressing plates, and seepage holes are formed in one side of each pipeline insertion hole of one loading pressing plate; two heating rod insertion holes are formed in the side face of the loading pressing plate, and four acoustic emission probe grooves are formed in the four corners of the loading pressing plate respectively.
In some embodiments, a square heat-shrinkable sealing rubber sleeve and a unidirectional hypertonic slide block are arranged between the sides of the sample, which are in contact with the loading pressing plate, the unidirectional hypertonic slide block is divided into an upper part, a middle part and a lower part, the upper part is a closed entity, the middle cavity is a diversion cavity, the lower part is a hypertonic plate fully distributed with diversion holes, the lower hypertonic plate is directly pressed on the side of the sample, a fracturing pipe joint is arranged on the upper part of the unidirectional hypertonic slide block, and a seepage pipe joint is also arranged on the upper part of the unidirectional hypertonic slide block on the side of the sample containing the fracturing holes, and each side of the unidirectional hypertonic slide block is filled and sealed through a sealing rubber strip.
In some embodiments, the fracturing modification system comprises a hydraulic fracturing module, a modifying hydraulic fracturing module, a liquid nitrogen fracturing module, and a supercritical carbon dioxide fracturing module; the hydraulic fracturing module, the modified hydraulic fracturing module, the liquid nitrogen fracturing module and the supercritical carbon dioxide fracturing module are respectively communicated with the fracturing pipe inside the sample, the hydraulic fracturing module provides water for fracturing for the fracturing pipe, the modified hydraulic fracturing module provides modified liquid for fracturing for the fracturing pipe, the liquid nitrogen fracturing module provides liquid nitrogen for fracturing for the fracturing pipe, and the supercritical carbon dioxide fracturing module provides carbon dioxide for fracturing for the fracturing pipe.
In some embodiments, the hydraulic fracturing module comprises a water tank A, a high-pressure injection pump, a pressure sensor A and a flow sensor A, wherein an input end pipeline of the high-pressure injection pump is connected with the water tank A, an output end pipeline is sequentially connected with a valve F, a valve B, the flow sensor A, the pressure sensor A and a communication conduit, and high-pressure water is led into a fracturing pipe inside a sample through the communication conduit to carry out hydraulic fracturing;
the modified hydraulic fracturing module comprises a modified liquid tank A, a modified liquid tank B, a high-pressure injection pump, a pressure sensor A and a flow sensor A, wherein an input end pipeline of the high-pressure injection pump is connected with the modified liquid tank A and the modified liquid tank B, an output end pipeline is sequentially connected with a valve F, the valve B, the flow sensor A, the pressure sensor A and a communication conduit, and a fracturing pipe for guiding modified liquid into a sample is used for fracturing modification through the communication conduit.
The liquid nitrogen fracturing module comprises a liquid nitrogen storage tank, a liquid nitrogen injector, an air compressor, a gas booster pump, a pressure buffer tank, a pressure reducing valve A, a pressure sensor A and a flow sensor A, wherein a gas injection port of the liquid nitrogen injector is sequentially connected with a valve L, the pressure reducing valve A, a valve K, the pressure buffer tank, a valve Q, a pressure sensor B, the gas booster pump, a valve P and the air compressor through pipelines, a liquid injection port of the liquid nitrogen injector is sequentially connected with a valve I, a valve B, the flow sensor A, the pressure sensor A and a communication conduit through pipelines, and the liquid injection port of the liquid nitrogen injector is sequentially connected with a valve J and the liquid nitrogen storage tank through branches.
The supercritical carbon dioxide fracturing module package is inside carbon dioxide gas pitcher, high-pressure injection pump, high low temperature test case, basin A, pressure sensor A and flow sensor A, high low temperature test case air inlet connects gradually valve E, valve M, carbon dioxide gas pitcher through the pipeline, its pressurization mouth connects gradually valve G, high pressure injection pump, basin A through the pipeline, its injection mouth connects gradually valve H through the pipeline, valve B, flow sensor A, pressure sensor A, the intercommunication pipe, its pressure release mouth is connected with basin A through the pipeline.
In some embodiments, the gas injection evaluation system includes a gas source, an air compressor, a gas booster pump, a buffer tank, a pressure relief valve B, and a metering tank; the gas booster pump is provided with a gas source inlet, a gas inlet and a pressure injection port, wherein the gas source inlet is sequentially connected with a valve N and a methane gas tank through a pipeline, and the gas source inlet is also respectively connected with a valve O, a valve M and a carbon dioxide gas tank through a branch; the air inlet of the gas booster pump is sequentially connected with a valve P and an air compressor through a pipeline; the gas booster pump injection port is sequentially connected with a pressure sensor B, a valve R, a buffer tank, a valve S, a pressure reducing valve B, a valve T, a flow sensor B, a valve V, a valve A and a communication conduit through pipelines, and the valve T and the valve V are sequentially connected with a valve U and a metering tank through branches.
In some embodiments, the back pressure monitoring system comprises an automatic back pressure pump, a water tank B, a back pressure buffer tank, a pressure sensor, a back pressure valve, a gas flow meter, a dry filter, a gas-liquid separator, and a measuring cylinder; the inlet end of the back pressure valve is sequentially connected with the valve W, the pressure sensor D and the communication guide pipe through pipelines, the outlet end of the back pressure valve is connected with the inlet end of the gas-liquid separator through pipelines, and the back pressure valve is further sequentially connected with the pressure sensor C, the back pressure buffer tank, the automatic back pressure pump and the water tank B through pipelines; the exhaust port of the gas-liquid separator is connected with the dry filter, the gas flowmeter and the air collecting bag in sequence through pipelines, and the liquid outlet of the gas-liquid separator is connected with the measuring cylinder through pipelines.
In some embodiments, the vacuum system comprises a vacuum pump and a pressure sensor, the vacuum pump being connected in series by a conduit to valve X, pressure sensor E, valve Y, valve a and a communication conduit.
In some embodiments, the sensors include pressure sensors A-E, a flow sensor A, flow sensors B3-18 and a strain sensor, wherein the pressure sensor A is used for monitoring injection pressure of fracturing media, the pressure sensor B is used for monitoring output pressure of a gas booster pump injection port, the pressure sensor C is used for monitoring output pressure of an automatic back pressure pump, the pressure sensor D is used for monitoring pressure of a gas-liquid discharge port of a true triaxial loading system, the pressure sensor E is used for monitoring negative pressure of a vacuum system, the flow sensor A is used for monitoring medium injection flow rate of a fracturing modification system, the flow sensor B is used for monitoring medium injection flow rate of a gas injection evaluation system, and the strain sensor is used for monitoring strain of a sample under different loading conditions.
Compared with the prior art, the invention has the following beneficial effects:
1. the invention can carry out whole-process research on aspects of coal seam fracturing modification, seepage characteristics, adsorption and desorption characteristics, mechanical characteristics and the like under in-situ conditions (true triaxial stress, temperature, water content and gas pressure) so as to realize omnibearing evaluation on the effects of fracturing modified coal bodies of different media.
2. According to the invention, the unidirectional hypertonic sliding blocks are arranged outside 6 sides of the cube sample, so that dynamic test of the anisotropic permeability (in X, Y, Z directions) before and after sample fracturing modification is realized;
3. the method can fully consider the influence of the fracturing medium on the physical and chemical modification of the coal rock mass, and form macroscopic diversion cracks by injecting the high-pressure fracturing medium into the coal rock mass, and simultaneously consider the modification effects of the fracturing medium on the microscopic pore structure, the surface characteristics and the mineral components of the coal rock mass, and quantitatively evaluate the effects of the fracturing medium on the modified coal rock mass by measuring the parameters such as mechanical parameters, adsorption and desorption amounts, anisotropic permeability and the like before and after the fracturing modification of the coal rock mass.
Drawings
FIG. 1 is a schematic structural diagram of a coal rock mass fracturing modification and effect evaluation test system of the invention;
FIG. 2 is a schematic diagram of a true triaxial loading system according to the present invention;
FIG. 3 is a schematic view of the structure of the loading platen of the present invention;
FIG. 4 is a schematic structural view of a unidirectional hypertonic slide of the invention;
FIG. 5 is a cross-sectional view of a unidirectional hypertonic slide of the invention.
In the figure:
1-true triaxial loading system; 1-1, a hydraulic cylinder body; 1-2-displacement sensor; 1-3-loading chamber; 1-4-valve A; 1-5-a pressure sensor a; 1-6-flow sensor a; 1-7-valve B;1-8, loading a push rod; 1-9, pipeline cavity holes; 1-10-communicating conduits; 1-11-a push rod sealing assembly; 1-12-loading press plate; 1-13-seepage holes; 1-14, a pipeline channel; 1-15-line channels; 1-16-square heat-shrinkable sealing rubber sleeve; 1-17, a sealing rubber strip; 1-18, a rubber sleeve interface; 1-19-a unidirectional hypertonic slide block; 1-20-sample; 1-21-fracturing the tube; 1-22, pipeline jacks; 1-23 parts of an acoustic emission probe groove; 1-24-heating rod insertion holes; 1-25-a fracturing pipe joint; 1-26-a seepage pipe joint; 1-27, a diversion cavity; 1-28-diversion holes;
2-a fracturing modification system; 2-1-a modified liquid tank A; 2-valve C; 2-3-a modified liquid tank B; 2-4-valve D; 2-5-high pressure injection pump; 2-6-sink A;2-7 parts of a high-low temperature test chamber; 2-8-valve E; 2-9-valve F; 2-10-valve G; 2-11-valve H; 2-12-a liquid nitrogen storage tank; 2-13-valve I;2-14, valve J; 2-15-liquid nitrogen injector; 2-16, a pressure buffer tank; 2-17-valve K; 2-18-a pressure reducing valve A; 2-19-valve L;
3-a gas injection evaluation system; 3-1-a carbon dioxide tank; 3-2-methane tank; 3-valve M; 3-4-valve N; 3-5-valve O; 3-6-an air compressor; 3-7-valve P; 3-8-gas booster pumps; 3-9-a pressure sensor B; 3-10-valve Q; 3-11-valve R; 3-12-a cache tank; 3-13-valve S; 3-14-a pressure reducing valve B; 3-15-valve T; 3-16-metering tank; 3-17-valve U; 3-18-flow sensor B; 3-19-valve V;
4-a back pressure monitoring system; 4-1-a water tank B; 4-2-an automatic return pressure pump; 4-3-back pressure buffer tank; 4-pressure sensor C; 4-5-back pressure valve; 4-6-valve W;4-7, a pressure sensor D;4-8—a gas flow meter; 4-9, drying and filtering; 4-10-a gas-liquid separator; 4-11-measuring cylinder; 4-12-collecting air bags;
5-a hydraulic servo control system;
6, a vacuum system; 6-1, a vacuum pump; 6-2-valve X; 6-3-pressure sensor E; 6-4-valve Y;
7, integrating data acquisition and control systems.
Detailed Description
Embodiments of the present invention will be described in further detail below with reference to fig. 1-5.
1-5, a coal rock mass fracturing modification and effect evaluation test system comprises a true triaxial loading system 1, a fracturing modification system 2, an air injection evaluation system 3, a back pressure monitoring system 4, a hydraulic servo control system 5, a vacuum system 6 and a data acquisition and control system integration 7; the true triaxial loading system 1 mainly comprises a hydraulic cylinder body 1-1, a loading chamber 1-2, a loading push rod 1-8, a loading pressing plate 1-12, a unidirectional hypertonic slide block 1-19 and other auxiliary components; the hydraulic cylinders 1-1 are divided into three pairs, and each pair is arranged in the X, Y, Z direction and used for loading and unloading the main stress of the samples 1-20 in the three directions, and each hydraulic cylinder 1-1 is connected with the hydraulic servo control system 5 through an oil pipe. The hydraulic servo control system 5 can respectively inject or output hydraulic oil into the six hydraulic cylinders 1-1 according to test requirements, control the pressure and flow of the hydraulic oil, and push the loading push rod 1-8 through the hydraulic cylinders 1-1 to realize the true triaxial loading and unloading of the samples 1-20.
The loading chamber 1-3 is a cubic cavity positioned at the center of the true triaxial loading system 1, the side surface of the loading chamber is respectively provided with a pipeline channel 1-14 and a pipeline channel 1-15, an external injection pipeline or a pressure relief pipeline penetrates into the loading chamber through the pipeline channel 1-14, and circuits such as an acoustic emission monitoring system data line, a temperature control system data line and a strain monitoring data line penetrate into the loading chamber 1-3 through the pipeline channel 1-15 to be connected with each sensor. The loading push rods 1-8 vertically penetrate through the centers of six surfaces of the loading chamber 1-3 respectively, the outer ends of the loading push rods are connected with a hydraulic cylinder body pressure head outside the loading chamber 1-3, the inner ends of the loading push rods are connected with a loading pressing plate 1-12 positioned in the loading chamber 1-3, and push rod sealing assemblies 1-11 are arranged at sliding joints of the loading push rods 1-8 and the loading chamber 1-3; an L-shaped pipeline cavity hole 1-9 is arranged in the loading push rod 1-8, an inner hole is positioned at the center of an inner end head of the loading push rod 1-8, an outer hole is positioned at the side surface near the outer end head of the loading push rod 1-8, and a communicating conduit 1-10 is arranged in the pipeline cavity hole 1-9 and used for connecting a fracturing pipeline or a seepage pipeline. Six loading pressing plates 1-12 are respectively pressed on six side surfaces of the sample 1-20, pipeline insertion holes 1-22 are formed in the centers of the loading pressing plates 1-12, seepage holes 1-13 are formed in one side of each pipeline insertion hole 1-22 of one loading pressing plate 1-12, and the loading pressing plates 1-12 are pressed on the side surfaces of the sample 1-20 containing the fracturing holes; two heating rod insertion holes 1-24 are arranged on the side face of the loading pressing plate 1-12, and four acoustic emission probe grooves 1-23 are respectively arranged at the four corners of the loading pressing plate 1-12. Six unidirectional hypertonic slide blocks 1-19 are arranged between the sample 1-20 and the square heat-shrinkable sealing rubber sleeve 1-16, the unidirectional hypertonic slide blocks 1-19 are divided into an upper part, a middle part and a lower part, the upper part is a closed entity, the middle cavity is a diversion cavity 1-27, the lower part is a hypertonic plate fully distributed with diversion holes 1-28, the lower hypertonic porous plate is directly pressed on the side surface of the sample 1-20, the upper part of the unidirectional hypertonic slide blocks 1-19 is provided with a fracturing pipe joint 1-25, the upper part of the unidirectional hypertonic slide blocks 1-19 on the side surface of the sample 1-20 is also provided with a seepage pipe joint 1-26, and each side surface of the unidirectional hypertonic slide blocks 1-19 is filled and sealed through a sealing rubber strip 1-17.
The vacuum system 6 mainly comprises a vacuum pump 6-1, a pressure sensor 6-2 and a valve, wherein the vacuum pump 6-1 is sequentially connected with the valve X6-2, the pressure sensor E6-3, the valve Y6-4 and the valve A1-4 through pipelines, and the vacuum system 6 is used for vacuumizing and degassing the sample 1-20 during a test.
The fracturing modification system 2 comprises a hydraulic fracturing module, a modification hydraulic fracturing module, a liquid nitrogen fracturing module and a supercritical carbon dioxide fracturing module; the hydraulic fracturing module mainly comprises a water tank A2-6, a high-pressure injection pump 2-5, a valve, a pressure sensor A1-5 and a flow sensor A1-6, wherein an input end pipeline of the high-pressure injection pump 2-5 is connected with the water tank A2-6, an output end pipeline is sequentially connected with the valve F2-9, the valve B1-7, the flow sensor A1-6, the pressure sensor A1-5 and a communication conduit 1-10, and high-pressure water is led into a fracturing pipe 1-21 inside a sample 1-20 through the communication conduit 1-10 for hydraulic fracturing; the modified liquid fracturing module mainly comprises a modified liquid tank A2-1, a modified liquid tank B2-3, a high-pressure injection pump 2-5, a valve, a pressure sensor A1-5 and a flow sensor A1-6, wherein an input end pipeline of the high-pressure injection pump 2-5 is connected with the modified liquid tank A2-1 and the modified liquid tank B2-3, an output end pipeline is sequentially connected with the valve F2-9, the valve B1-7, the flow sensor A1-6, the pressure sensor A1-5 and a communication conduit 1-10, and a fracturing pipe 1-21 for introducing modified liquid into the sample 1-20 is used for fracturing modification through the communication conduit 1-10.
The liquid nitrogen fracturing module mainly comprises a liquid nitrogen storage tank 2-12, a liquid nitrogen injector 2-15, an air compressor 3-6, a gas booster pump 3-8, a pressure buffer tank 2-16, a pressure reducing valve A2-18, a valve, a pressure sensor A1-5 and a flow sensor A1-6, wherein a gas injection port of the liquid nitrogen injector 2-15 is sequentially connected with the valve L2-19, the pressure reducing valve A2-18, the valve K2-17, the pressure buffer tank 2-16, the valve Q3-10, the pressure sensor B3-9, the gas booster pump 3-8, the valve P3-7 and the air compressor 3-6 through pipelines, a liquid nitrogen injector 2-15 is sequentially connected with the valve I2-13, the valve B1-7, the flow sensor A1-6, the pressure sensor A1-5 and the communication conduit 1-10 through pipelines, and is further sequentially connected with the valve J2-14 and the liquid nitrogen storage tank 2-12 through branches.
The supercritical carbon dioxide fracturing module mainly comprises a carbon dioxide gas tank 3-1, a high-pressure injection pump 2-5, a high-low temperature test box 2-7, a water tank A2-6, a valve, a pressure sensor A1-5 and a flow sensor A1-6, wherein an air inlet of the high-low temperature test box 2-7 is sequentially connected with a valve E2-8, a valve M3-3 and the carbon dioxide gas tank 3-1 through pipelines, a pressurizing port of the high-low temperature test box is sequentially connected with a valve G2-10 through pipelines, the high-pressure injection pump 2-5 and the water tank A2-6, a pressure injection port of the high-low temperature test box is sequentially connected with a valve H2-11, a valve B1-7, the flow sensor A1-6, the pressure sensor A1-5 and a communication conduit 1-10 through pipelines, and a pressure release port of the high-low temperature test box is connected with the water tank A2-6 through pipelines;
The gas injection evaluation system 3 mainly comprises a gas source, an air compressor 3-6, a gas booster pump 3-8, a buffer tank 3-12, a pressure reducing valve B3-14, a metering tank 3-16, a valve, a pressure sensor A1-5 and a flow sensor A1-6; the gas booster pump 3-8 is respectively provided with a gas source inlet, a gas inlet and a pressure injection port, the gas source inlet is sequentially connected with the valve N3-4 and the methane gas tank 3-2 through pipelines, and the gas source inlet is also respectively connected with the valve O3-5, the valve M3-3 and the carbon dioxide gas tank 3-1 through branches; an air inlet of the gas booster pump 3-8 is sequentially connected with a valve P3-7 and an air compressor 3-6 through pipelines; the gas booster pump 3-8 is provided with a pressure injection port which is sequentially connected with a pressure sensor B3-9, a valve R3-11, a buffer tank 3-12, a valve S3-13, a pressure reducing valve B3-14, a valve T3-15, a flow sensor B3-18, a valve V3-19, a valve A1-4 and a communication conduit 1-10 through pipelines, and a valve U3-17 and a metering tank 3-16 are sequentially connected between the valve T3-15 and the valve V3-19 through branches.
The back pressure monitoring system 4 mainly comprises an automatic back pressure pump 4-2, a water tank B4-1, a back pressure buffer tank 4-3, a pressure sensor 4-4, a back pressure valve 4-5, a valve, a gas flowmeter 4-8, a dry filter 4-9, a gas-liquid separator 4-10 and a measuring cylinder 4-11; the inlet end of the back pressure valve 4-5 is sequentially connected with a valve W4-6, a pressure sensor D4-7 and a communication conduit 1-10 through pipelines, the outlet end of the back pressure valve is connected with the inlet end of the gas-liquid separator 4-10 through pipelines, and the back pressure valve 4-5 is also sequentially connected with a pressure sensor C4-4, a back pressure buffer tank 4-3, an automatic back pressure pump 4-2 and a water tank B4-1 through pipelines; the exhaust port of the gas-liquid separator 4-10 is connected with the dry filter 4-9, the gas flowmeter 4-8 and the air collecting bag 4-12 in sequence through pipelines, and the liquid outlet of the gas-liquid separator 4-10 is connected with the measuring cylinder 4-11 through pipelines.
The data acquisition and control system integration 7 mainly comprises a temperature control subsystem, an acoustic emission monitoring subsystem, a stress-strain monitoring subsystem, an automatic control subsystem, data acquisition and processing software and a sensor; the data acquisition and control system integration 7 monitors and controls the true triaxial loading system 1, the fracturing modification system 2, the gas injection evaluation system 3, the back pressure monitoring system 4, the hydraulic servo control system 5 and the vacuum system 6 through a sensor and an automatic control subsystem respectively; the sensor mainly comprises a pressure sensor A-E, a flow sensor A1-6, a flow sensor B3-18 and a strain sensor, wherein the pressure sensor A1-5 is used for monitoring injection pressure of fracturing media, the pressure sensor B3-9 is used for monitoring output pressure of an injection port of a gas booster pump, the pressure sensor C4-4 is used for monitoring output pressure of an automatic back pressure pump, the pressure sensor D4-7 is used for monitoring pressure of a gas-liquid outlet of a true triaxial loading system, the pressure sensor E6-3 is used for monitoring negative pressure of a vacuum system, the flow sensor A1-6 is used for monitoring injection flow of media of a fracturing modification system, the flow sensor B3-18 is used for monitoring injection flow of media of a gas injection evaluation system, and the strain sensor is used for monitoring strain of a sample under different loading conditions.
A coal rock mass fracturing modification and effect evaluation test method comprises the following main steps:
(a) Sample preparation and model assembly
Cutting a large block of coal rock sample retrieved from a field coal mining working face, processing the large block of coal rock sample into a cubic sample 1-20 with the diameter of 300 multiplied by 300mm, drilling a vertical drilling hole with the diameter of 10 multiplied by 150mm at the center of one side surface of the sample as a fracturing hole, inserting one end of a fracturing pipe 1-21 with sieve holes into the fracturing hole after the sample is dried, and sealing the fracturing hole by using sealant, so that the outer wall of the fracturing pipe at the sealing section and the inner wall of the drilling hole are firmly sealed; the bottom surfaces of the unidirectional hypertonic sliding blocks 1-19 containing the diversion holes are respectively fixed on six side surfaces of a sample, the lower ends of the fracturing pipe joints 1-25 are in sealing connection with the fracturing pipe 1-21, the side surfaces between the adjacent hypertonic sliding blocks are respectively filled and sealed through sealing rubber strips 1-17, and then the whole body of the unidirectional hypertonic sliding blocks is put into a square heat-shrinkable sealing rubber sleeve 1-16 for sealing, so that rubber sleeve interfaces 1-18 are respectively aligned with the positions of the fracturing pipe joints 1-25 and the seepage pipe joints 1-26 on the unidirectional hypertonic sliding blocks 1-19; the thermocouple heating rod and the sound emission probe are respectively arranged in a heating rod jack 1-24 and a sound emission probe groove 1-23 which are arranged on the loading pressing plate, then the loading pressing plate 1-12 is respectively pressed on six faces of the square heat-shrinkable sealing rubber sleeve 1-16, so that the pipeline jack 1-22 and the seepage hole 1-13 on the loading pressing plate 1-12 are respectively aligned with the rubber sleeve joint 1-18, and the model assembly is completed.
(b) System connection
Connecting the system components through pipelines or lines according to a set connection mode, placing an assembled sample into the loading chamber 1-3, respectively connecting the communication pipes 1-10 arranged in the six loading push rods 1-8 to the fracturing pipe joints 1-25 through the rubber sleeve interfaces 1-18, connecting the seepage pipe to the seepage pipe joints 1-26 through the rubber sleeve interfaces 1-18, and sealing the rubber sleeve interfaces 1-18; connecting a pipeline of a fracturing modification system to a communication conduit 1-10 connected with a fracturing pipe 1-21, respectively connecting pipelines of a gas injection evaluation system 3 and a back pressure monitoring system 4 to the communication conduit 1-10 on the opposite sides of a sample according to different measured seepage directions, connecting a pipeline of a vacuum system 6 and a pipeline of the gas injection evaluation system 3 to the communication conduit 1-10 after being connected in parallel through a tee joint, and connecting each hydraulic cylinder body 1-1 of a true triaxial loading system 1 to a hydraulic servo control system 5 through an oil pipe; the data lines of the individual sensors and the system control elements are connected to a data acquisition and control system integration 7.
(c) Initial parameter determination
The gas injection evaluation system 3 and the back pressure monitoring system 4 are utilized to carry out a sample permeability measurement test, and under the initial in-situ condition of the samples 1-20, initial permeability of the samples 1-20 in three directions (the direction of setting parallel fracturing holes as X direction) of X, Y, Z is respectively measured; during the permeability measurement test, a pipeline of a gas injection evaluation system 3 is connected to a seepage pipe joint 1-26 of a true triaxial loading system through a pipeline channel 1-14, a pipeline of a back pressure monitoring system 4 is connected to a communication pipe 1-10 in the X direction, a valve M3-3, a valve P3-7 and a valve R3-11 are firstly opened, methane in a methane tank 3-2 is pressurized by a gas booster pump 3-8 and then filled in a buffer tank 3-12, the output pressure of the gas booster pump 3-8 is monitored by a pressure sensor B3-9, a valve S3-13, a valve T3-15, a valve V3-19 and a valve A1-4 are opened, and the pressure of the gas inlet end of a sample 1-20 is controlled by a pressure reducing valve B3-14 P X1 By flow sensingThe devices B3-18 monitor the injection flow rate of the gasQ X Simultaneously, the automatic pressure return pump 4-2 is used for injecting the pressure required by the test into the pressure return buffer tank 4-3, the pressure sensor C4-4 is used for monitoring the pressure of the pressure return in real time, the pressure of the pressure return is kept stable, then the valve W4-6 is opened, and the pressure of the air outlet end of the sample 1-20 is monitored through the pressure sensor D4-7P X2 The method comprises the steps of carrying out a first treatment on the surface of the According to the pressure and flow data collected on the data collection and control system integration 7, the permeability of the sample in the X direction can be obtained according to a gas permeability calculation formula
The method comprises the steps of carrying out a first treatment on the surface of the In the method, in the process of the invention,K X for the permeability in the X direction (10 -15 m 2 )；Q X Is the gas flow (cm) 3 /s)；P 0 Atmospheric pressure (0.101 MPa); μ is the gas viscosity coefficient (pa·s); l is the specimen height (cm); a is the cross-sectional area (cm) of the cubic sample 2 )；P X1 AndP X2 the pressure values (MPa) of the air inlet end and the air outlet end of the sample are respectively.
Similarly, when the permeability in the Y, Z direction is measured, only the pipelines of the gas injection evaluation system 3 and the back pressure monitoring system 4 are respectively connected to the communication guide pipes 1-10 in the Y, Z direction, and the pressure values of the gas inlet end and the gas outlet end of the sample 1-20 in the Y, Z direction are respectively measuredP Y1 、P Y2 AndP Z1 、P Z2 and a vent flow in the Y, Z directionQ Y 、Q Z Then, the permeability of samples 1 to 20 in the direction Y, Z was determined
、/>
。
And (3) carrying out adsorption and desorption tests on the samples 1-20 by using a vacuum system 6, a gas injection evaluation system 3, a back pressure monitoring system 4 and a stress strain monitoring system, and measuring the methane adsorption quantity, the desorption quantity, the adsorption deformation quantity and the desorption deformation quantity of the samples 1-20 under different gas pressures. When the methane gas adsorption test is carried out, firstly, the valve A1-4, the valve X6-2 and the valve Y6-4 are opened, the vacuum pump 6-1 is utilized to vacuumize the sample 1-20 for 12 hours, then the vacuum system 6 is closed, the valve M3-3, the valve P3-7 and the valve R3-11 are opened, the gas booster pump 3-8 is utilized to boost methane in the methane tank 3-2 and then fill the buffer tank 3-12, the output pressure of the gas booster pump 3-8 is monitored through the pressure sensor B3-9, the valve S3-13, the valve T3-15 and the valve U3-17 are opened, the pressure required by the test is injected into the metering tank 3-16 through the pressure reducing valve B3-14, the valve T3-15 is closed, the valve V3-19 and the valve A1-4 are opened, methane gas is introduced into the sample 1-20, the pressure change of the metering tank 3-16 is monitored in real time until the pressure is constant, the methane adsorption quantity of the sample 1-20 under the pressure is obtained according to the pressure change of the metering tank 3-16, and the pressure is monitored through the strain sensor to finish the gas adsorption process under the pressure of the sample. When the methane gas desorption test of the sample 1-20 is carried out, firstly, the valve A1-4 is closed, the back pressure of the back pressure monitoring system 4 is set to be the standard atmospheric pressure, the valve W4-6 is opened, methane gas desorbed from the coal body of the sample 1-20 enters the gas collecting bag 4-12 through the gas-liquid separator 4-10, the dry filter 4-9 and the gas flowmeter 4-8, the instantaneous flow and the total flow of the gas are monitored in real time through the gas flowmeter 4-8, the instantaneous desorption rate and the accumulated desorption amount of the methane gas are obtained, and meanwhile, the strain amount of the sample 1-20 is monitored through the strain sensor; and continuously filling methane with different pressures into the metering tank 3-16 according to the steps, and carrying out adsorption and desorption tests of the samples 1-20 under different gas pressures to obtain methane adsorption capacity, desorption capacity, adsorption deformation capacity and desorption deformation capacity of the samples 1-20 under different gas pressures.
And (3) respectively carrying out uniaxial compression test on the samples 1-20 in three directions of X, Y, Z by using the true triaxial loading system 1 until the elastic limit of the samples 1-20 is reached, acquiring dynamic stress-strain values of the samples 1-20 in the whole loading process by using a stress strain monitoring system, and obtaining initial elastic modulus and poisson ratio of the samples 1-20 in the three directions of X, Y, Z.
(d) In situ condition simulation
Firstly, vacuumizing a sample for 12 hours through a vacuum system 6, and setting corresponding conditions such as triaxial loading parameters, temperature, water content, gas pressure and the like according to actual in-situ conditions of a coal seam; respectively applying main stress to the three groups of opposite surfaces of the samples 1-20 through the hydraulic servo control system 5, and simulating the in-situ ground stress state of the coal bed; the temperature control subsystem is used for controlling a thermocouple heating rod in the loading pressing plate 1-12 to heat the sample 1-20 to the temperature required by the test, and the in-situ temperature state of the coal seam is simulated; injecting a certain amount of water into the coal rock samples 1-20 by utilizing a hydraulic fracturing module of the fracturing modification system, and simulating the in-situ water content of the coal bed; and filling methane with a certain pressure into the samples 1-20 by using the gas injection evaluation system 3, and simulating the in-situ gas pressure condition of the coal seam.
(e) Fracturing modification
Closing the gas injection evaluation system 3 and the back pressure monitoring system 4, opening the fracturing modification system 2, and performing fracturing tests on different fracturing media on the samples 1-20 by utilizing a hydraulic fracturing module, a modified hydraulic fracturing module, a liquid nitrogen fracturing module and a supercritical carbon dioxide fracturing module in the fracturing modification system 2; during the test, the fracturing medium is injected into the sample 1-20 at high pressure to fracture the coal rock mass, the acoustic emission change of the sample 1-20 in the fracturing process is monitored through an acoustic emission monitoring system, and the crack initiation and propagation evolution parameters in the sample 1-20 are determined by utilizing a three-dimensional acoustic emission positioning technology; and then maintaining a certain fracturing medium injection pressure, and carrying out pressure maintaining modification on the coal rock mass so that different fracturing media fully react with the coal rock mass in a physical-chemical way.
The fracturing modification test mainly comprises a hydraulic fracturing test, a modified hydraulic fracturing test, a liquid nitrogen fracturing test and a supercritical carbon dioxide fracturing test; when a hydraulic fracturing test is carried out, the valves B1-7 and the valves F2-9 are opened, water in the water tank A2-6 is injected into the coal rock sample 1-20 by using a high-pressure injection pump to carry out fracturing and permeability improvement, and the water injection pressure and flow are monitored in real time through the pressure sensor A1-5 and the flow sensor A1-6 arranged on a fracturing pipeline.
When a modified liquid fracturing test is carried out, a valve C2-2, a valve B1-7 and a valve F2-9 are opened, a high-pressure injection pump 2-5 is firstly utilized to inject modified liquid A in a modified liquid tank A2-1 into a coal rock sample 1-20 for fracturing and permeability improvement, the injection pressure and flow of the modified liquid are monitored in real time through a pressure sensor A1-5 and a flow sensor A1-6 arranged on a fracturing pipeline, and then the pressure maintaining modification is carried out on the coal rock mass for a period of time with a certain injection pressure, so that the modified liquid fully has a physical and chemical effect with the coal rock mass; in addition, two kinds of modified liquid can be used for a synergistic anti-reflection test, and the specific method is that after the modified liquid A is modified, a back pressure measurement system 4 is utilized to carry out back flow of the modified liquid A, after the back flow is finished, a valve C2-2 is closed, a valve D2-4 is opened, then a high pressure injection pump 2-5 is utilized to inject the modified liquid B in a modified liquid tank B2-3 into a coal rock sample 1-20 for secondary pressure maintaining and modification, and thus the synergistic modification of the two kinds of modified liquid is realized.
When a liquid nitrogen fracturing test is carried out, firstly, a valve J2-14 is opened, liquid nitrogen in a liquid nitrogen storage tank 2-12 is injected into a liquid nitrogen injector 2-15, after the liquid nitrogen injector 2-15 is filled with liquid nitrogen, the valve J2-14 is closed, a valve P3-7 and a valve Q3-10 are opened, high-pressure air is injected into a pressure buffer tank 2-16, a valve L2-19, a valve I2-13 and a valve B17 are opened, the output pressure of the pressure buffer tank 2-16 is controlled by a pressure reducing valve A2-18, liquid nitrogen in the liquid nitrogen injector 2-15 is injected into a sample 1-20 at the pressure required by the test, liquid nitrogen fracturing anti-reflection is carried out, the liquid nitrogen injection pressure and flow are monitored in real time through a pressure sensor A1-5 and a flow sensor A1-6 arranged on a fracturing pipeline, and then a certain injection pressure is maintained for a period of time, and the pressure maintaining modification is carried out on a coal rock body, so that the liquid nitrogen is fully reacted with the coal rock body.
When the supercritical carbon dioxide fracturing test is carried out, firstly, the valve E2-8 and the valve M3-3 are opened, carbon dioxide gas in the carbon dioxide gas tank 3-1 is injected into an injector in the high-low temperature test box 2-7, after the carbon dioxide gas tank is filled with the carbon dioxide gas, the valve E2-8 and the valve M3-3 are closed, the valve G2-10 is opened, the injector in the high-low temperature test box 2-7 is pressurized to the critical pressure of 7.4MPa by using the high-pressure injection pump 2-5, the temperature of the high-low temperature test box 2-7 is regulated to the critical temperature of 31.3 ℃, carbon dioxide in the injector is in a supercritical state, then the valve H2-11 and the valve B1-7 are opened, supercritical carbon dioxide is injected into the sample 1-20 by using the high-pressure injection pump 2-5 to carry out fracturing and permeability improvement, and the injection pressure and flow of the supercritical carbon dioxide are monitored in real time by using the pressure sensor A1-5 and the flow sensor A1-6 arranged on a fracturing pipeline, and the coal rock mass is maintained for a certain period of time, so that the supercritical carbon dioxide is fully subjected to pressure maintaining and chemical action with the coal rock mass.
(f) Evaluation of Effect
After the fracturing modification test is finished, closing the fracturing modification system 2, opening the gas injection evaluation system 3 and the back pressure monitoring system 4, performing flowback on fracturing media in the samples 1-20 by using the back pressure monitoring system 4, after flowback is finished, measuring the adsorption and desorption amounts of the samples 1-20 after fracturing under different gas pressure conditions and the permeability of the samples in the directions X, Y, Z according to the method in the step (c), and then measuring the elastic modulus and the poisson ratio of the samples 1-20 after fracturing in the directions X, Y, Z according to the method in the step (c) respectively; and quantitatively evaluating the effect of different fracturing media on fracturing the modified coal and rock mass according to the adsorption and desorption amounts of the samples 1-20 before and after the fracturing modification, the permeability in different directions, the elastic modulus and the Poisson ratio.
It is to be clearly understood that the above description and illustration is made only by way of example and not as a limitation on the disclosure, application or use of the invention. Although embodiments have been described in the embodiments and illustrated in the accompanying drawings, the invention is not limited to the specific examples illustrated by the drawings and described in the embodiments as the best mode presently contemplated for carrying out the teachings of the invention, and the scope of the invention will include any embodiments falling within the foregoing specification and the appended claims.
Claims (10)
1. The utility model provides a coal rock mass fracturing modification and effect evaluation test system thereof which characterized in that: the device comprises a fracturing modification system (2), an air injection evaluation system (3), a back pressure monitoring system (4), a hydraulic servo control system (5), a vacuum system (6) and a data acquisition and control system integration (7), wherein a loading cavity (1-3) with a cubic cavity is arranged at the center of a true triaxial loading system (1), a loading push rod (1-8) penetrates through the centers of six surfaces of the loading cavity (1-3), the outer end of the loading push rod (1-8) is connected with a hydraulic cylinder body (1-1), the inner end of the loading push rod (1-8) is connected with a loading pressing plate (1-12) positioned in the loading cavity (1-3), and six loading pressing plates (1-12) are respectively pressed on six side surfaces of a sample (1-20);
the loading pressing plate (1-12) is provided with a thermocouple heating rod which is controlled by a data acquisition and control system integration (7);
a fracturing hole is drilled in the center of one side surface of the sample (1-20);
a push rod sealing component (1-11) is arranged at the sliding connection part of the loading push rod (1-8) and the loading chamber (1-3);
an L-shaped pipeline cavity hole (1-9) is formed in the loading push rod (1-8), an inner hole opening of the L-shaped pipeline cavity hole is positioned at the center of an inner end head of the loading push rod (1-8), an outer hole opening of the L-shaped pipeline cavity hole is positioned on the side surface near the outer end head of the loading push rod (1-8), a communication conduit (1-10) is arranged in the pipeline cavity hole (1-9), and the communication conduits (1-10) in three loading push rods (1-8) in the six surfaces are respectively used for connecting a fracturing modification system (2), an air injection evaluation system (3), a back pressure monitoring system (4) and a vacuum system (6);
Wherein the fracturing modification system (2) provides different fracturing media for the samples (1-20);
the gas injection evaluation system (3) injects the gas under different gas pressures into the samples (1-20);
the back pressure monitoring system (4) is used for sucking out the gas in the samples (1-20);
the vacuum system (6) vacuumizes the loading chamber (1-3);
the data acquisition and control system integration (7) monitors and controls the true triaxial loading system (1), the fracturing modification system (2), the gas injection evaluation system (3), the back pressure monitoring system (4), the hydraulic servo control system (5) and the vacuum system (6) through sensors respectively;
and the hydraulic servo control system (5) injects or outputs hydraulic oil into the true triaxial loading system (1) according to test requirements.
2. The coal rock mass fracturing modification and effect evaluation test system according to claim 1, wherein: the centers of the loading pressing plates (1-12) are respectively provided with a pipeline jack (1-22), and one side of the pipeline jack (1-22) of one loading pressing plate (1-12) is also independently provided with a seepage hole (1-13); two heating rod insertion holes (1-24) are formed in the side face of the loading pressing plate (1-12), and four acoustic emission probe grooves (1-23) are formed in the four corners of the loading pressing plate (1-12) respectively.
3. The coal rock mass fracturing modification and effect evaluation test system according to claim 1, wherein: a square heat-shrinkable sealing rubber sleeve (1-16) and a unidirectional hypertonic slide block (1-19) are arranged between the side surfaces of the sample (1-20) contacted with the loading pressing plate (1-12), the unidirectional hypertonic slide block (1-19) is divided into an upper part, a middle part and a lower part, the upper part is a closed entity, a middle cavity is a diversion cavity (1-27), the lower part is a hypertonic plate which is fully covered with a diversion hole (1-28), the lower hypertonic plate is directly pressed on the side surface of the sample (1-20), a fracturing pipe joint (1-25) is arranged on the upper part of the unidirectional hypertonic slide block (1-19), and a seepage pipe joint (1-26) is also arranged on the upper part of the unidirectional hypertonic slide block (1-19) on the side surface of the fracturing hole of the sample (1-20), and each side surface of the unidirectional hypertonic slide block (1-19) is filled and sealed through a sealing rubber strip (1-17).
4. The coal rock mass fracturing modification and effect evaluation test system according to claim 1, wherein: the fracturing modification system (2) comprises a hydraulic fracturing module, a modification hydraulic fracturing module, a liquid nitrogen fracturing module and a supercritical carbon dioxide fracturing module; the hydraulic fracturing module, the modified hydraulic fracturing module, the liquid nitrogen fracturing module and the supercritical carbon dioxide fracturing module are respectively communicated with fracturing pipes (1-21) in the test sample (1-20), the hydraulic fracturing module provides water for fracturing the fracturing pipes (1-21), the modified hydraulic fracturing module provides modified liquid for fracturing the fracturing pipes (1-21), the liquid nitrogen fracturing module provides liquid nitrogen for fracturing the fracturing pipes (1-21), and the supercritical carbon dioxide fracturing module provides carbon dioxide for fracturing the fracturing pipes (1-21).
5. The coal rock mass fracturing modification and effect evaluation test system according to claim 4, wherein: the hydraulic fracturing module comprises a water tank A (2-6), a high-pressure injection pump (2-5), a pressure sensor A (1-5) and a flow sensor A (1-6), wherein an input end pipeline of the high-pressure injection pump (2-5) is connected with the water tank A (2-6), an output end pipeline is sequentially connected with a valve F (2-9), a valve B (1-7), the flow sensor A (1-6), the pressure sensor A (1-5) and a communication conduit (1-10), and high-pressure water is guided into a fracturing pipe (1-21) inside a sample (1-20) through the communication conduit (1-10) to carry out hydraulic fracturing;
the modified hydraulic fracturing module comprises a modified liquid tank A (2-1), a modified liquid tank B (2-3), a high-pressure injection pump (2-5), a pressure sensor A (1-5) and a flow sensor A (1-6), wherein an input end pipeline of the high-pressure injection pump (2-5) is connected with the modified liquid tank A (2-1) and the modified liquid tank B (2-3), an output end pipeline is sequentially connected with a valve F (2-9), a valve B (1-7), the flow sensor A (1-6), the pressure sensor A (1-5) and a communication conduit (1-10), and a fracturing pipe (1-21) for guiding modified liquid into a sample (1-20) through the communication conduit (1-10) is used for carrying out fracturing modification;
The liquid nitrogen fracturing module comprises a liquid nitrogen storage tank (2-12), a liquid nitrogen injector (2-15), an air compressor (3-6), a gas booster pump (3-8), a pressure buffer tank (2-16), a pressure reducing valve A (2-18), a pressure sensor A (1-5) and a flow sensor A (1-6), wherein an air injection port of the liquid nitrogen injector (2-15) is sequentially connected with a valve L (2-19), the pressure reducing valve A (2-18), a valve K (2-17), the pressure buffer tank (2-16), a valve Q (3-10), a pressure sensor B (3-9), a gas booster pump (3-8), a valve P (3-7) and the air compressor (3-6) through pipelines, and an air injection port of the liquid nitrogen injector (2-15) is sequentially connected with a valve I (2-13), a valve B (1-7), a flow sensor A (1-6), a pressure sensor A (1-5) and a communication conduit (1-10) through pipelines, and the air injection port is also sequentially connected with a valve J (2-14) and the storage tank (2-12) through liquid nitrogen branches;
the supercritical carbon dioxide fracturing module comprises a carbon dioxide gas tank (3-1), a high-pressure injection pump (2-5), a high-low temperature test box (2-7), a water tank A (2-6), a pressure sensor A (1-5) and a flow sensor A (1-6), wherein an air inlet of the high-low temperature test box (2-7) is sequentially connected with a valve E (2-8), a valve M (3-3) and the carbon dioxide gas tank (3-1) through pipelines, a pressurizing port of the high-pressure injection pump is sequentially connected with a valve G (2-10), the high-pressure injection pump (2-5) and the water tank A (2-6) through pipelines, and a pressure injection port of the high-pressure injection pump is sequentially connected with a valve H (2-11), a valve B (1-7), the flow sensor A (1-6), the pressure sensor A (1-5) and a communication conduit (1-10) through pipelines, and a pressure releasing port of the high-pressure injection pump is connected with the water tank A (2-6) through pipelines.
6. The coal rock mass fracturing modification and effect evaluation test system according to claim 1, wherein: the gas injection evaluation system (3) comprises a gas source, an air compressor (3-6), a gas booster pump (3-8), a buffer tank (3-12), a pressure reducing valve B (3-14) and a metering tank (3-16); the gas booster pump (3-8) is provided with a gas source inlet, a gas inlet and a pressure injection port, the gas source inlet is sequentially connected with the valve N (3-4) and the methane gas tank (3-2) through pipelines, and the gas source inlet is also respectively connected with the valve O (3-5), the valve M (3-3) and the carbon dioxide gas tank (3-1) through branches; an air inlet of the gas booster pump (3-8) is sequentially connected with a valve P (3-7) and an air compressor (3-6) through pipelines; the gas booster pump (3-8) is characterized in that a pressure injection port is sequentially connected with a pressure sensor B (3-9), a valve R (3-11), a buffer tank (3-12), a valve S (3-13), a pressure reducing valve B (3-14), a valve T (3-15), a flow sensor B (3-18), a valve V (3-19), a valve A (1-4) and a communication conduit (1-10) through pipelines, and a valve U (3-17) and a metering tank (3-16) are sequentially connected between the valve T (3-15) and the valve V (3-19) through branches.
7. The coal rock mass fracturing modification and effect evaluation test system according to claim 1, wherein: the back pressure monitoring system (4) comprises an automatic back pressure pump (4-2), a water tank B (4-1), a back pressure buffer tank (4-3), a pressure sensor (4-4), a back pressure valve (4-5), a gas flowmeter (4-8), a drying filter (4-9), a gas-liquid separator (4-10) and a measuring cylinder (4-11); the inlet end of the back pressure valve (4-5) is sequentially connected with the valve W (4-6), the pressure sensor D (4-7) and the communication conduit (1-10) through pipelines, the outlet end of the back pressure valve is connected with the inlet end of the gas-liquid separator (4-10) through pipelines, and the back pressure valve (4-5) is also sequentially connected with the pressure sensor C (4-4), the back pressure buffer tank (4-3), the automatic back pressure pump (4-2) and the water tank B (4-1) through pipelines; the exhaust port of the gas-liquid separator (4-10) is connected with the drying filter (4-9), the gas flowmeter (4-8) and the air collecting bag (4-12) in sequence through pipelines, and the liquid discharge port of the gas-liquid separator (4-10) is connected with the measuring cylinder (4-11) through pipelines.
8. The coal rock mass fracturing modification and effect evaluation test system according to claim 1, wherein: the vacuum system (6) comprises a vacuum pump (6-1) and a pressure sensor (6-2), wherein the vacuum pump (6-1) is sequentially connected with a valve X (6-2), a pressure sensor E (6-3), a valve Y (6-4), a valve A (1-4) and a communication conduit (1-10) through pipelines.
9. The coal rock mass fracturing modification and effect evaluation test system according to claim 1, wherein: the pressure sensor comprises a pressure sensor A-E, a flow sensor A (1-6), a flow sensor B (3-18) and a strain sensor, wherein the pressure sensor A (1-5) is used for monitoring injection pressure of fracturing media, the pressure sensor B (3-9) is used for monitoring output pressure of an injection port of a gas booster pump, the pressure sensor C (4-4) is used for monitoring output pressure of an automatic back pressure pump, the pressure sensor D (4-7) is used for monitoring pressure of a gas-liquid outlet of a true triaxial loading system, the pressure sensor E (6-3) is used for monitoring negative pressure of a vacuum system, the flow sensor A (1-6) is used for monitoring medium injection flow of a fracturing modification system, the flow sensor B (3-18) is used for monitoring medium injection flow of a gas injection evaluation system, and the strain sensor is used for monitoring strain of a sample under different loading conditions.
10. A test method based on the coal rock mass fracturing modification and effect evaluation test system of claim 1, which is characterized in that: comprising the following steps, including the following steps,
s1: manufacturing a sample and an assembly model;
S2: the device comprises a true triaxial loading system (1), a fracturing modification system (2), an air injection evaluation system (3), a back pressure monitoring system (4), a hydraulic servo control system (5), a vacuum system (6) and a data acquisition and control system integration (7);
s3: performing a permeability measurement test of the sample by using the gas injection evaluation system (3) and the back pressure monitoring system (4);
carrying out adsorption and desorption tests on the samples (1-20) by using a vacuum system (6), a gas injection evaluation system (3) and a back pressure monitoring system (4), and measuring the methane adsorption quantity, desorption quantity, adsorption deformation quantity and desorption deformation quantity of the samples (1-20) under different gas pressures;
carrying out uniaxial compression test on the sample (1-20) in three directions of X, Y, Z by utilizing a true triaxial loading system (1) until the elastic limit of the sample (1-20), acquiring dynamic stress-strain values of the sample (1-20) in the whole loading process by a stress-strain monitoring system, and obtaining initial elastic modulus and poisson ratio of the sample (1-20) in the three directions of X, Y, Z;
s4: in-situ condition simulation, vacuumizing a sample through a vacuum system (6), and setting corresponding triaxial loading parameters, temperature, water content and gas pressure according to the actual in-situ condition of a coal seam; respectively applying main stress to the three groups of opposite surfaces of the samples (1-20) through a hydraulic servo control system (5), and simulating the in-situ stress state of the coal bed; the thermocouple heating rod in the loading pressing plate (1-12) is controlled by the data acquisition and control system integration (7), the sample (1-20) is heated to the temperature required by the test, and the in-situ temperature state of the coal seam is simulated; injecting a certain amount of water into a coal rock sample (1-20) by utilizing a hydraulic fracturing module of a fracturing modification system, and simulating the in-situ water content of a coal bed; filling methane with a certain pressure into the sample (1-20) by using a gas injection evaluation system (3), and simulating the in-situ gas pressure condition of the coal bed;
S5: closing the gas injection evaluation system (3) and the back pressure monitoring system (4), opening the fracturing modification system (2), and performing fracturing tests of different fracturing media on the samples (1-20) by utilizing a hydraulic fracturing module, a modified hydraulic fracturing module, a liquid nitrogen fracturing module and a supercritical carbon dioxide fracturing module in the fracturing modification system (2);
s6: after the fracturing modification test is finished, closing the fracturing modification system (2), opening the gas injection evaluation system (3) and the back pressure monitoring system (4), performing back discharge on fracturing media in the samples (1-20) by using the back pressure monitoring system (4), after the back discharge is finished, measuring the adsorption and desorption amounts of the samples (1-20) after fracturing under different gas pressure conditions and the permeability of the samples in the directions X, Y, Z according to the method in the step (c), and then measuring the elastic modulus and the poisson ratio of the samples (1-20) after fracturing in the directions X, Y, Z according to the method in the step (c) respectively; and quantitatively evaluating the effect of different fracturing media on fracturing the modified coal rock mass according to the adsorption and desorption amount of the samples (1-20) before and after the fracturing modification, the permeability in different directions, the elastic modulus and the Poisson ratio.
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| CN117489290A (en) * | 2023-12-14 | 2024-02-02 | 江苏宏泰石化机械有限公司 | Remote-adjustment opening and closing degree adjustable fracturing wellhead and adjusting and controlling method thereof |
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| CN117489290B (en) * | 2023-12-14 | 2024-03-01 | 江苏宏泰石化机械有限公司 | Remote-adjustment opening and closing degree adjustable fracturing wellhead and adjusting and controlling method thereof |
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