WO2020087860A1 - Coalbed methane horizontal well hole collapse pressure relief mining simulation test system - Google Patents

Abstract

A coalbed methane horizontal well hole collapse pressure relief mining simulation test system. A coal reservoir is constructed by means of reconstruction of a coal measure strata structure and simulation of a similar material simulation subsystem; a pressure pulsation excitation pressure relief simulation subsystem achieves horizontal well pressure pulsation excitation and stress release, a coal-liquid-gas mixture is displaced hydraulically to be migrated to a straight well section; an electric simulation subsystem achieves detection of electric field distribution in similar materials, a product separation and detection subsystem separates and weighs coal, liquid and gas, and a data acquisition and control subsystem detects and controls the operation and implementation processes of equipment in real time. The system can achieve the simulation of soft-structured coal reservoir horizontal well hole collapse and stress release, simulate migration features of a gas phase, a liquid phase and a solid phase in a pressure relief space, simulate the separation process of the produced mixture, and obtain the law between coal reservoir pressure relief and gas desorption change and the dynamic law between a complex seepage field after coal measure strata excitation and pressure relief and horizontal well section flow.

Description

Simulation test system for pressure relief mining of coal-bed methane horizontal well collapse hole making cave Technical field

The invention relates to a coal bed methane mining simulation test system, in particular to a coal bed methane horizontal well collapse hole cavern pressure relief mining simulation test system, which belongs to the field of coal bed methane mining.

Background technique

Tectonic coal refers to coal that is subjected to tectonic stress, and the original structure and structure are damaged by strong cracks, resulting in fracture, crumpling, and polishing surface. The extensive development of tectonic coal and the richness of tectonic coal and CBM resources are the distinguishing characteristics of China ’s coal and CBM resources. Tectonic coal resources account for a high proportion of China ’s discovered coal resources, and tectonic coal CBM resources account for the country ’s total CBM resources. The proportion is greater. Structural coal has outburst characteristics such as rich gas, low permeability, and softness. Most of them are coal and gas outburst coal seams. Due to the great harm and the difficulty of extraction and utilization, coal mines often discharge their wind into the atmosphere to efficiently develop coal seam gas. It has very outstanding significance for energy, safety and ecology.

The method based on the theory of hydrophobic decompression desorption gas production is currently the main method of in-situ CBM surface well development. Due to the extremely low permeability of the structural coal reservoir and the poor effectiveness of the hydraulic fracturing and other transformation methods, the theory of hydrophobic decompression desorption gas production It is not suitable for use in structural coal reservoirs. The exploration and development practice results also show that the CBM exploration and development technologies based on the theory of hydrophobic decompression and desorption gas production include the SVR technology series (straight well fracturing, U-shaped wells, multi-branch horizontal wells, Horizontal well fracturing, etc.), the ECBM technology series (CO ₂ -ECBM, N ₂ -ECBM, etc.) and their composite technologies cannot achieve the efficient development of structural coal-bed methane. Therefore, the construction of coalbed methane efficient exploration and development technology and equipment has become one of the important technical bottlenecks restricting the rapid scale development of China's coalbed methane industry.

With the in-depth study of coal bed methane mining technology, the protection layer structure coal seam gas mining pressure relief and permeation development theory of coal mine area provides new ideas for the in situ mining of coal seam gas in structured coal. The pressure relief mining simulation test system for in-situ CBM wells in structural coal has important theoretical and practical production guidance significance for breaking the technical bottleneck of high-efficiency development of surface coal-bed methane wells in China.

Summary of the invention

In order to solve the above problems, the present invention provides a coalbed methane horizontal well collapse hole cavern pressure relief mining simulation test system, which can simulate the soft structure coal reservoir horizontal well collapse hole cavern and stress relief, simulate gas-liquid-solid three The migration characteristics of the phases in the pressure relief space and the separation process of the produced mixture are simulated to obtain the coal bed pressure relief and gas desorption change laws, the complex seepage field and the horizontal well section flow dynamic law after the coal system formation is stimulated and pressure relief, in order to achieve the structure Provide guidance for the efficient and continuous development of coal bed methane in situ.

In order to achieve the above objectives, the present invention adopts the following technical scheme: a coal mine methane horizontal well collapse hole cavern pressure relief mining simulation test system, including coal system stratum structure reconstruction and similar material simulation subsystem, pressure pulsation excitation pressure relief simulator System, electrical simulation subsystem, output separation detection subsystem and data acquisition control subsystem;

The coal system stratum structure reconstruction and similar material simulation subsystem includes a sample compartment, a gas injection device, a constant temperature room and a confining pressure loading device, and multiple valves. The sample compartment is a sealed hexahedron formed by six movable steel plates connected Similar materials of coal measures are placed in the sample warehouse. The similar materials are the top similar material rock layer, the similar material coal layer, and the bottom similar material rock layer from top to bottom. The similar material is provided with a U-shaped well composed of horizontal wells and vertical wells. The horizontal section of the horizontal well is located in the coal seam of similar materials; the X-direction servo station, Y-direction servo station and Z-direction servo station in the confining pressure loading device are respectively hydraulically connected to the corresponding loading pistons outside the sample chamber, and correspondingly provided on the connecting pipelines X-direction pressure sensor, Y-direction pressure sensor and Z-direction pressure sensor; the inlet of the booster pump in the gas injection device is connected to the outlet pipelines of the helium high-pressure gas cylinder, carbon dioxide high-pressure gas cylinder and methane high-pressure gas cylinder, and the outlet pipeline It is connected with the horizontal well in the coal seam of similar material in the sample warehouse, and the power input port is connected with the outlet of the air compressor, from the outlet of the booster pump to the water A pressure reducing valve, a gas mass flow controller and a pressure sensor 1 are successively arranged on the communication pipeline of the flat well; a pressure sensor, a temperature sensor, a strain gauge and a saturation probe are arranged near the lower end of the similar material coal seam;

The pressure pulsation excitation pressure relief simulation subsystem includes a fluid injection device and a downhole injection device. The fluid injection device includes a hydraulic pump, a hydraulic cylinder, a high modulus spring, and an impact pressure chamber. A branch of the outlet of the hydraulic pump passes electromagnetic The valve is hydraulically connected to the hydraulic cylinder, the other branch is connected to the impact pressure chamber through a solenoid valve, the right end of the guide rod is fixedly connected to the right mounting plate of the high modulus spring, and the left end passes through and slides with the left mounting plate of the high modulus spring Connected, the piston rod of the hydraulic cylinder is arranged coaxially with the guide rod, and a clutch is provided between the end surface of the piston rod of the hydraulic cylinder and the left end surface of the guide rod; the left end of the impact piston in the impact pressure chamber extends out of the impact pressure chamber and is connected with the high modulus spring The right mounting plate of the pump is fixedly connected; the pressure sensor two is provided on the outlet pipe of the hydraulic pump, the displacement sensor one is provided on the right mounting plate of the high modulus spring, and the water inlet pipe of the hydraulic pump is placed in the liquid storage tank; the downhole injection device The horizontal section of the horizontal well placed in the coal seam of similar materials is close to the wellhead side, and the outlet pipeline of the impact pressure chamber is connected to the downhole injection device;

The electrical simulation subsystem includes a power supply and a measurement device. The high potential end of the power supply is electrically connected to a copper belt placed in a horizontal well in a similar material coal seam, and the low potential end is electrically connected to the high potential end of the measurement device. The measurement device The low potential end of the is electrically connected to the copper on the inner wall of the sample compartment;

The output separation and detection subsystem includes a gas-liquid-solid separator, an electronic balance weighing device 1, an electronic balance weighing device 2, and a gas collection bottle. The inlet of the gas-liquid-solid separator is connected to the outlet of a similar material coal seam. The gas outlet is connected to the gas collection bottle, the liquid outlet and the solid outlet are respectively connected to the electronic balance weighing device 1 and the electronic balance weighing device 2, and a gas flow is provided on the communication pipeline between the gas-liquid-solid separator and the gas collection bottle meter;

The data acquisition and control subsystem includes acquisition hardware and data processing software. The hardware includes a workstation, printer, and acquisition card. The acquisition card is composed of PCI8360 and CP-168; the software is used for parameter setting, control, and real-time data display of each component , And process the collected data to obtain data reports and graphs and generate a test database.

Further, the simulation experiment system further includes a vacuum pump, and the vacuum pump communicates with the outlet pipeline of the vertical well in the coal seam of similar material.

Further, the pressure pulsation excitation pressure relief simulation subsystem further includes an abrasive tank and a mixing chamber, the outlet of the abrasive tank and the outlet of the impact pressure chamber communicate with the mixing chamber, and the outlet of the mixing chamber communicates with the downhole injection device.

Further, the gas injection device further includes a gas storage tank, a one-way valve and a pressure regulating valve, the inlet of the gas storage tank communicates with the outlet of the booster pump; the one-way valve is provided in the gas mass flow controller and the pressure sensor 1 Between, the outlet faces the pressure sensor one; the pressure regulating valve is located at the outlet of the air compressor.

Further, the pressure pulsation excitation pressure relief simulation subsystem further includes a constant speed constant pressure pump and an intermediate container, the inlet of the intermediate container is connected to the constant speed constant pressure pump, and the outlet of the intermediate container is connected to the outlet pipeline of the impact pressure chamber.

Further, the output separation detection subsystem further includes a dryer, which is provided between the gas-liquid-solid separator and the gas flow meter.

Further, a pressure gauge 1, a pressure gauge 2 and a pressure gauge 3 are respectively provided in the outlet pipelines of the helium high-pressure gas cylinder, the carbon dioxide high-pressure gas cylinder and the methane high-pressure gas cylinder, and the communication pipe is connected between the air compressor and the booster pump There is a pressure gauge four on the road, a pressure gauge five on the inlet pipeline of the gas storage tank, and a pressure gauge six on the inlet pipeline of the gas mass flow controller.

Further, the coal system stratum structure reconstruction and similar material simulation subsystem further includes an X-direction displacement sensor, a Y-direction displacement sensor and a Z-direction displacement sensor, which are respectively provided on the corresponding plugging pistons.

Further, the strain measuring instrument is a distributed optical fiber measuring instrument, which is distributed along the horizontal section of the horizontal well in the coal seam of similar materials.

According to the principle of similarity, the present invention configures similar simulated materials corresponding to the physical and mechanical characteristics of the coal reservoir, injects high-pressure gas into the similar material coal seam through the gas injection device to simulate the geological pressure inside the coal seam, and loads the simulated coal seam surrounding the sample warehouse Pressure to provide a basis for simulating the in-situ coal bed methane mining of structural coal as realistic and accurate as possible;

The high-pressure pulsation device is composed of a hydraulic cylinder, a hydraulic pump, a high-modulus spring, and an impact pressure chamber, which injects high-pressure and high-speed fluid into the horizontal well cave at a certain pulse frequency, and further cuts and crushes the coal body, realizing the simulated structure of coal-bed methane horizontal well pressure Pulsating excitation and stress release, and realize the hydraulic displacement of coal-liquid-gas mixture along the pressure relief space to the vertical well section, which provides guarantee for subsequent lifting;

The electrical simulation subsystem measures the potential changes in similar materials during the test, and then obtains the fluid field changes of similar materials; through the gas-liquid-solid separator, the high-efficiency separation and weighing of the coal, liquid, and gas of the produced mixture is achieved;

Through the acquisition hardware and data processing software, real-time detection, control of the operation and implementation process of the test equipment are realized, test data collection, display and processing analysis are realized. The cooperative operation of various subsystems in the entire mining system realizes the simulation of coal production High-efficiency continuous development of CBM.

BRIEF DESCRIPTION

Figure 1 is the overall principle diagram of the system of the present invention.

In the picture: 1.1, helium high-pressure gas cylinder, 1.2, carbon dioxide high-pressure gas cylinder, 1.3, methane high-pressure gas cylinder, 1.41, pressure gauge one, 1.42, pressure gauge two, 1.43, pressure gauge three, 1.44, pressure gauge four, 1.45 , Pressure gauge five, 1.46, pressure gauge six, 1.51, valve one, 1.52, valve two, 1.53, valve three, 1.54, valve four, 1.55, valve five, 1.56, valve six, 1.57, valve seven, 1.58, valve eight , 1.59, valve nine, 1.6, air compressor, 1.7, booster pump, 1.8, gas storage tank, 1.9, pressure reducing valve, 1.10, gas mass flow controller, 1.11, check valve, 1.12, pressure sensor one, 1.13, pressure regulating valve, 2.1, reservoir, 2.2, hydraulic pump, 2.31, pressure sensor two, 2.32, pressure sensor three, 2.4, hydraulic cylinder, 2.5, high modulus spring, 2.51, guide rod, 2.6, displacement sensor 1. 2.7, impact pressure chamber, 2.71, impact piston, 2.81, valve ten, 2.82, valve eleven, 2.83, valve twelve, 2.84, valve thirteen, 2.85, valve fourteen, 2.86, valve fifteen, 2.87, Valve sixteen, 2.88, valve seventeen, 2.9, intermediate container, 2.10 Constant speed and constant pressure pump, 2.11, abrasive tank, 2.12, globe valve, 2.13, mixing chamber, 3.1, power supply, 3.2, measuring device, 4.1, sample compartment, 4.21, Z-direction hydraulic servo station, 4.22, X-direction hydraulic servo station , 4.23, Y direction hydraulic servo station, 4.31, Z direction pressure sensor, 4.32, X direction pressure sensor, 4.33, Y direction pressure sensor, 4.41, Z direction displacement sensor, 4.42, X direction displacement sensor, 4.43, Y direction displacement sensor 5. Vacuum pump, 5.1, valve 18, 6.1, gas-liquid-solid separator, 6.2, dryer, 6.3, gas flow meter, 6.4, electronic balance weighing device 1, 6.5, electronic balance weighing device 2, 6.6, Valve 19, 6.7, gas collection bottle.

detailed description

The present invention will be further described below with reference to the drawings.

As shown in Fig. 1, a simulation test system for pressure relief mining of collapsed holes in coal-bed methane horizontal wells includes a coal-measure formation structural reconstruction and similar material simulation subsystem, pressure pulsation excitation pressure relief simulation subsystem, and electrical simulation subsystem , Output separation detection subsystem and data collection control subsystem;

The coal system stratum structure reconstruction and similar material simulation subsystem includes a sample compartment 4.1, a gas injection device, a constant temperature room (not shown in the figure) and a confining pressure loading device. The sample compartment 4.1 is connected by six movable steel plates The formed sealed hexahedron, with a sealed interface connected to other subsystems, is placed in the sample compartment 4.1 with similar materials of coal strata. The similar materials are the top layer of similar material rock layer (simulating coal roof) from top to bottom, similar material coal layer, The bottom layer is a similar material rock layer (simulating a coal seam floor). A U-shaped well composed of horizontal wells and vertical wells is arranged in the similar material. The horizontal section of the horizontal well is located in the coal seam of similar materials; the X-direction servo station 4.22, Y in the confining pressure loading device The directional servo station 4.23 and the Z directional servo station 4.21 are respectively hydraulically connected to the corresponding loading piston outside the sample chamber 4.1, and the connection pipeline is respectively provided with an X direction pressure sensor 4.32, a Y direction pressure sensor 4.33 and a Z direction pressure sensor 4.31, three A hydraulic servo station is used to increase the confining pressure to the similar material coal layer 1.4, and three pressure sensors are used to detect the loading pressure in three directions; gas injection The inlet of the booster pump 1.7 in the device is connected to the outlet pipes of the helium high-pressure gas bottle 1.1, the carbon dioxide high-pressure gas bottle 1.2 and the methane high-pressure gas bottle 1.3, and the outlet pipe is connected to the horizontal well in the coal seam of similar material in the sample chamber 4.1. The power inlet is connected to the 1.6 outlet of the air compressor, and the communication pipeline from the 1.7 outlet of the booster pump to the horizontal well is provided with a pressure relief valve 1.9, a gas mass flow controller 1.10 and a pressure sensor 1.12; the coal seam of similar materials is near the lower end There are pressure sensors (not shown in the figure), temperature sensors (not shown in the figure), strain gauges (not shown in the figure) and saturation probes (not shown in the figure) for measuring tests Pressure, temperature and strain of coal seams of similar materials in the process; at the outlets of helium high-pressure gas cylinder 1.1, carbon dioxide high-pressure gas cylinder 1.2 and methane high-pressure gas cylinder 1.3, there are valve one 1.51, valve two 1.52 and valve three 1.53, respectively. Between the booster pump 1.7 and the air compressor 1.6, there is a valve four 1.54, between the booster pump 1.7 and the pressure reducing valve 1.9, there is a valve six 1.56, and the outlet line of the booster pump 1.7 is connected to the atmospheric branch, There is a valve 1.55 on the branch road. The gas mass flow controller 1.10 is provided with a valve seven 1.57 and a valve nine 1.59 at the inlet and outlet respectively, a valve eight 1.58 is provided on the parallel branch connecting the valve seven 1.57 inlet and the valve nine 1.59 outlet, and the pressure sensor a 1.12 and water The flat well communication pipeline is provided with a valve 16.28. All the above valves are used to control the flow of gas in the pipeline;

The pressure pulsation excitation pressure relief simulation subsystem includes a fluid injection device and a downhole injection device. The fluid injection device includes a hydraulic pump 2.2, a hydraulic cylinder 2.4, a high modulus spring 2.5 and an impact pressure chamber 2.7, and the outlet of the hydraulic pump 2.2 One branch is hydraulically connected to the hydraulic cylinder 2.4 through the solenoid valve, and the other branch is connected to the impact pressure chamber 2.7 through the solenoid valve. The right end of the guide rod 2.51 is fixedly connected to the right mounting plate of the high modulus spring 2.5, and the left end passes through the high mold The left mounting plate of the measuring spring 2.5 is slidingly connected to it. The piston rod of the hydraulic cylinder 2.4 is arranged coaxially with the guide rod 2.51, and a clutch is provided between the end surface of the piston rod of the hydraulic cylinder 2.4 and the left end surface of the guide rod 2.51 (not shown in the figure) ); The left end of the impact piston 2.71 in the impact pressure chamber 2.7 extends out of the impact pressure chamber 2.7 and is fixedly connected to the right mounting plate of the high modulus spring 2.5; the outlet pipe of the hydraulic pump 2.2 is provided with a pressure sensor II 2.31, high modulus spring The right mounting plate of 2.5 is equipped with a displacement sensor 2.6, the water inlet pipeline of the hydraulic pump 2.2 is placed in the reservoir 2.1; the downhole injection device is placed in the horizontal section of the horizontal well near the wellhead in a similar material coal seam Side, the impact of the pressure chamber 2.7 downhole injection device outlet conduit communicating with the communicating pipeline provided with a valve thirteen 2.84;

The electrical simulation subsystem includes a power supply 3.1 and a measuring device 3.2. The high potential end of the power supply 3.1 is electrically connected to a copper belt placed in a horizontal well in a similar material coal seam, and the low potential end is electrically connected to the high potential end of the measuring device 3.2 Connection, the low potential end of the measuring device 3.2 is electrically connected to the copper strip on the inner wall of the sample compartment 4.1; the difference in the potential gradient measured during the test reflects the distribution characteristics of the electric field, thus reflecting the change in resistivity, according to the measured similar material resistance Rate, the water saturation can be calculated by Archie's formula;

The output separation and detection subsystem includes a gas-liquid-solid separator 6.1, an electronic balance weighing device 6.4, an electronic balance weighing device two 6.5, and a gas collection bottle 6.7. The inlet of the gas-liquid-solid separator 6.1 and similar materials The coal seam straight well outlet is connected, the gas outlet is connected with the gas collection bottle 6.7, the liquid outlet and the solid outlet are connected with the electronic balance weighing device 1 6.4 and the electronic balance weighing device 2 respectively, and the gas liquid solid separator 6.1 is connected with the gas collection bottle 6.7 There is a gas flow meter 6.3 on the connecting pipeline between the outlet of the vertical well of similar material coal seam and the gas-liquid-solid separator 6.1. A valve 19 6.6 is provided on the connecting pipeline between the outlet of the vertical well of a similar material coal seam and the gas-liquid-solid separator. 6.1. Gravity separation method is used to achieve gas separation, and the remaining fluid is further filtered to achieve liquid-solid separation. The weight of solid and liquid is weighed with an electronic balance, and the gas flow rate is detected with a gas flow meter. The test data can realize gas-liquid-solid three-phase seepage simulation test;

The data acquisition control subsystem includes acquisition hardware and data processing software. The hardware includes workstations, printers, acquisition cards, etc. The acquisition card is composed of PCI8360, CP-168, etc .; the software is used for parameter setting, control and data of each component Real-time display, and process the collected data to obtain data reports and graphs and generate test database.

The simulation experiment system further includes a vacuum pump 5, which is connected to the outlet pipeline of the vertical well in a coal seam of similar material, and the communication pipeline is provided with a valve 18 5.1, which is used to evacuate the test system and improve the accuracy of the test.

The pressure pulsating excitation pressure relief simulation subsystem also includes an abrasive tank 2.11 and a mixing chamber 2.13, an outlet of the abrasive tank 2.11, an impact pressure chamber 2.7 outlet and the mixing chamber 2.13, the outlet of the mixing chamber 2.13 is connected with the downhole injection device; Adding a certain proportion of abrasives to the liquid can increase the ability of the excitation liquid to cut coal and rock, and improve the mining efficiency. A shut-off valve 1.12 is provided at the outlet of the abrasive tank 2.11, which is used to input the abrasive in the mixing chamber 2.13 of the control box; The pipeline between the downhole injection device is equipped with a general valve for controlling fluid, namely valve 17 2.88; the outlet pipe of the impact pressure chamber 2.7 is provided with a branch communicating with the abrasive tank 2.11 tank port, and a pressure sensor three 2.32 is provided on the branch ; There is a valve 10.81 on the pipeline between the impact pressure chamber 2.7 and the pressure sensor three 2.32, and a valve fourteen 2.85 on the pipeline between the pressure sensor three 2.32 and the abrasive tank 2.11; on the top of the abrasive tank 2.11 There are valves fifteen 2.86.

The gas injection device further includes a gas storage tank 1.8, a one-way valve 1.11 and a pressure regulating valve 1.13. The inlet of the gas storage tank 1.8 communicates with the outlet of the booster pump 1.7, which is used to buffer gas to ensure a stable pressure in the system; The directional valve 1.11 is set between the gas mass flow controller 1.10 and the pressure sensor 1.12, and its outlet faces the pressure sensor 1.12, so that the gas in the system can only flow in one direction, avoiding the gas backflow resulting in unstable gas pressure and test data Is not accurate; the pressure regulating valve 1.13 is located at the outlet of the air compressor 1.6 to adjust the gas pressure of the air compressor 1.6 so that the gas output by the air compressor 1.6 can drive the booster pump 1.7 more smoothly.

The pressure pulsation excitation pressure relief simulation subsystem further includes a constant speed and constant pressure pump 2.10 and an intermediate container 2.9. The inlet of the intermediate container 2.9 is communicated with the constant speed and constant pressure pump 2.10. A valve twelve 2.83 is provided on the communication pipeline. The intermediate container The outlet of 2.9 is connected to the outlet pipe of the impact pressure chamber 2.7. There is a valve 11.82 on the connecting pipe; when pulse pressure is not needed to stimulate pressure relief, a constant speed and constant pressure pump 2.10 can be used to transport the coal liquid gas mixture and the intermediate container. Make the liquid flow rate and pressure more stable.

The output separation and detection subsystem further includes a dryer 6.2, which is located between the gas-liquid-solid separator 6.1 and the gas flow meter 6.3, and is used for drying the gas product to improve the test accuracy.

In the outlet pipelines of the helium high-pressure gas cylinder 1.1, the carbon dioxide high-pressure gas cylinder 1.2 and the methane high-pressure gas cylinder 1.3, there are a pressure gauge 1.41, a pressure gauge II 1.42 and a pressure gauge III 1.43, the air compressor 1.6 and the booster pump There is a pressure gauge IV 1.44 on the communication pipeline between 1.7, a pressure gauge V 1.45 on the inlet pipeline of the gas storage tank 1.8, and a pressure gauge VI 1.46 on the inlet pipeline of the gas mass flow controller 1.10; The gas pressure at the pipelines in the device is detected to facilitate the collection of test data and to control the test more accurately.

The coal system stratum structure reconstruction and similar material simulation subsystem also includes an X-direction displacement sensor 4.42, a Y-direction displacement sensor 4.43 and a Z-direction displacement sensor 4.41, which are respectively arranged on corresponding plugging pistons, and three displacement sensors are used to Detecting the displacement of the loading piston in three directions makes it easier to control the confining pressure of the simulated coal seam more accurately.

The strain measuring instrument is a distributed optical fiber measuring instrument, which is distributed along the horizontal section of a horizontal well in a coal seam of similar materials; an optical fiber grating embedded strain gauge is used to measure the deformation of the coal seam of similar materials during the test, so as to observe similar materials for a long time Structural stress and strain changes and state analysis.

The specific test process includes the following steps:

1) According to the logging and logging data, determine the experimental simulated stratigraphic sequence and basic properties, including lithology, mechanical properties, water content, and pore characteristics;

According to the principle of similarity, the calculation test simulates the characteristics of similar materials in the formation, including thickness, density, mechanical properties, water content, permeability, porosity; calculate the length and diameter of the horizontal and vertical wells simulated by the test;

Using pulverized coal, quartz sand, gypsum, cement, shell powder, cement as the main material, by adjusting the ratio of materials, make similar materials, and carry out density, seepage characteristics, adsorption, mechanical properties, pore characteristics, permeability Test, to check whether the similar material ratio is consistent with the calculated similar material characteristics, if it is inconsistent, change the ratio and reconfigure the similar material until the two are consistent;

According to the thickness of coal and rock layer calculated according to the principle of stratigraphic sequence and similarity, according to the adjusted similar material ratio, the top layer of similar material rock layer, similar material coal layer and bottom layer similar material rock layer are laid from top to bottom in the sample compartment 4.1. Arrange stress sensors, temperature sensors, strain gauges and saturation probes, and wet similar materials according to actual water content. When laying, reserve U-shaped well space, reserved length and diameter of well sections and similar principles The calculation results are consistent, and the underground injection system is buried in the reserved horizontal well space, the underground injection system and its pipe string are wrapped with copper tape, and copper tape is laid on the inner wall of the sample compartment 4.1;

2) Arrange the location of each device and connect the devices; place the sample compartment 4.1 in a constant temperature room (not shown in the figure) to preheat to reach the test design temperature;

Open valve 1.51, valve four 1.54, valve six 1.56, valve seven 1.57, valve nine 1.59 and valve sixteen 2.87, inject He into the similar material coal seam in the sample chamber 4.1 to the experimental design pressure, and open the X direction hydraulic servo station 4.22 1. The hydraulic servo station in Y direction 4.23 and the hydraulic servo station in Z direction 4.21, increase the confining pressure to the sample designation 4.1 to the test design pressure; check the air tightness of the device; if the air tightness is qualified, proceed to the next step; if the air tightness is not Pass, repeat steps 1) and 2);

3) Close valve 1.51, open valve ten 2.81, valve thirteen 2.84, valve seventeen 2.88, valve eighteen 5.1 and valve nineteen 6.6, start vacuum pump 5, remove He from the entire test system pipeline and treat the system Vacuum;

4) Close valve 10.28, valve 13 2.84, valve 17 2.88, valve 18 5.1 and valve 19 6.6, open valve 2 1.52 or valve 3 1.53, and inject CO ₂ or CH into the similar material coal seam in the sample chamber 4.1 ₄ (Considering CH _{4 is} explosive, it is better to use N ₂ instead) until the gas pressure in the sample compartment 4.1 is stable at the test design pressure, at the same time, open the X direction hydraulic servo station 4.22, Y direction hydraulic servo station 4.23 and Z direction hydraulic servo station 4.21, increase the confining pressure to the test design pressure in the sample compartment 4.1;

5) Close all valves, and stop the air compressor 1.6 and booster pump 1.7; open valve X 2.81, valve XIII 2.84 and valve XVII 2.88, and set the high modulus according to the pulse frequency, pressure and speed required by the test The compression length of the spring 2.5 (that is, the displacement detected by the displacement sensor), the injection pressure and speed of the hydraulic pump 2.2, the operating frequency of the clutch; start the hydraulic pump 2.2 to inject liquid into the hydraulic cylinder 2.4 and the impact pressure chamber 2.7, the clutch works, hydraulic The cylinder 2.4 piston rod drives the guide rod 2.51 to move to the left to compress the high modulus spring 2.5. When the displacement sensor 2.6 detects the compression degree of the high modulus spring 2.5 (that is, the high modulus spring 2.5 has the displacement of the mounting plate), the experimental design is reached When compressing the length, the clutch stops working, the guide rod 2.51 is disengaged from the piston rod of the hydraulic cylinder 2.4, the restoring force of the high modulus spring 2.5 makes the impact piston 2.71 move quickly to the right, and forms an instantaneous pulse power to the liquid in the impact pressure chamber 2.7, high After the release force of the modulus spring 2.5 is completed, the hydraulic cylinder 2.4 piston rod moves to the right, and the clutch works, driving the guide rod 2.51 to engage the hydraulic cylinder 2.4 piston rod and move to the left During the process of recompressing the spring and releasing the pulse power, the liquid in the impact pressure chamber 2.7 will be injected into the horizontal well of the similar material coal seam by the downhole injection system at the pulse frequency, pressure and rate of the experimental design, and the similar material coal seam will be cut and broken , Causing horizontal collapse of horizontal wells of similar material coal seams to form pressure relief caverns and displacing the gas-liquid-coal mixture to the vertical wells; at the same time, strain gauges, temperature sensors, pressure sensors and saturation probes Measure the changes of stress, strain, temperature and saturation in coal seams of similar materials. The measured data can be further calculated to obtain the changes in mechanical properties of similar materials and the gas desorption conditions, relative permeability of water phase and relative permeability of gas phase caused by the pressure relief of similar materials. The measurement device 3.2 measures the potential change inside the similar material, and then the change of the fluid field in the similar material can be determined;

6) Close all valves and stop the hydraulic pump 2.2; open the valve 19 and 6.6 to lift the coal-liquid-gas mixture downhole of similar material coal seam to the outside of the well and enter the gas-liquid-solid separator 6.1 to separate the coal seam Gas, excitation liquid and coal powder enter the gas collection bottle 6.7, electronic balance weighing device one 6.4 and electronic balance weighing device two 6.5;

7) After the test, remove the gas and loading confining pressure in the sample compartment 4.1, disassemble the pipeline, open the sample compartment 4.1, remove the similar materials after the test, downhole injection system, sensors, measuring instruments and probes, etc. Inside the sample compartment 4.1.

When performing step 5), the shut-off valve 2.12 can be opened at the same time, so that the abrasive in the abrasive tank 2.11 enters the mixing chamber 2.13 to form a solid-liquid mixed fluid, which can enhance the cutting ability of the excitation liquid to similar materials.

In step 1), coalbed mineralized water or 8% NaCl solution is used for wetting, which can ensure that the similar materials after wetting are as close as possible to the actual bottom material parameters.

Two or more distributed optical fiber measuring instruments are laid in the coal seam of similar materials. When the distributed optical fiber measuring instruments are more than two layers, the distributed optical fiber measuring instruments are arranged at equal intervals in the height direction; Strain to provide theoretical guidance for actual production.

Claims (9)

1. A coal mine methane horizontal well collapse hole cavern pressure relief mining simulation test system, which is characterized by including coal system stratum structure reconstruction and similar material simulation subsystem, pressure pulsation excitation pressure relief simulation subsystem, electrical simulation subsystem, production Object separation detection subsystem and data acquisition control subsystem;

   The coal system stratum structure reconstruction and similar material simulation subsystem includes a sample compartment (4.1), a gas injection device, a constant temperature room and a confining pressure loading device, and multiple valves. The sample compartment (4.1) is composed of six movable steel plates Sealed hexahedrons connected together, similar materials of coal stratum are placed in the sample compartment (4.1), similar materials are top layer similar material rock layer, similar material coal layer, bottom layer similar material rock layer from top to bottom. The horizontal sections of U-shaped wells and horizontal wells composed of straight wells are located in coal seams of similar materials; the X-direction servo station (4.22), Y-direction servo station (4.23) and Z-direction servo station (4.21) in the confining pressure loading device are respectively The corresponding hydraulic connection of the loading piston on the outside of the sample chamber (4.1) is provided with an X-direction pressure sensor (4.32), a Y-direction pressure sensor (4.33) and a Z-direction pressure sensor (4.31) on the connecting pipeline; The inlet of the booster pump (1.7) is connected to the outlet pipes of the helium high-pressure gas cylinder (1.1), carbon dioxide high-pressure gas cylinder (1.2) and methane high-pressure gas cylinder (1.3), and the outlet pipe is similar to the sample chamber (4.1) Material Coal Seam The horizontal well is connected, the power input port is connected to the outlet of the air compressor (1.6), and the communication pipeline from the outlet of the booster pump (1.7) to the horizontal well is provided with a pressure relief valve (1.9), a gas mass flow controller (1.10) and Pressure sensor one (1.12); pressure sensors, temperature sensors, strain gauges and saturation probes are provided near the lower end in similar material coal seams;

   The pressure pulsation excitation pressure relief simulation subsystem includes a fluid injection device and a downhole injection device. The fluid injection device includes a hydraulic pump (2.2), a hydraulic cylinder (2.4), a high modulus spring (2.5) and an impact pressure chamber (2.7) , One branch of the outlet of the hydraulic pump (2.2) is hydraulically connected to the hydraulic cylinder (2.4) through a solenoid valve, and the other branch is connected to the impact pressure chamber (2.7) through a solenoid valve, and the right end of the guide rod (2.51) is connected to the high The right mounting plate of the modulus spring (2.5) is fixedly connected, the left end passes through the left mounting plate of the high modulus spring (2.5) and is slidingly connected thereto, the piston rod of the hydraulic cylinder (2.4) and the guide rod (2.51) are arranged coaxially, A clutch is provided between the end face of the piston rod of the hydraulic cylinder (2.4) and the left end face of the guide rod (2.51); the left end of the impact piston (2.71) in the impact pressure chamber (2.7) extends out of the impact pressure chamber (2.7) and is connected with a high modulus The right mounting plate of the spring (2.5) is fixedly connected; the pressure sensor two (2.31) is provided on the outlet pipe of the hydraulic pump (2.2), and the displacement sensor one (2.6) is provided on the right mounting plate of the high modulus spring (2.5), The water inlet pipeline of the hydraulic pump (2.2) is placed in the reservoir (2.1); the downhole injection device is placed in a coal seam of similar material Hirai horizontal section near the wellhead side impact pressure chamber (2.7) of the outlet conduit means in communication with a downhole injection;

   The electrical simulation subsystem includes a power supply (3.1) and a measuring device (3.2), the high potential end of the power supply (3.1) is electrically connected to a copper strip placed in a horizontal well in a similar material coal seam, the low potential end and the measuring device (3.2) The high potential end is electrically connected, and the low potential end of the measuring device (3.2) is electrically connected to the copper wall of the inner wall of the sample compartment (4.1);

   The output separation and detection subsystem includes a gas-liquid-solid separator (6.1), an electronic balance weighing device one (6.4), an electronic balance weighing device two (6.5), and a gas collection bottle (6.7). The inlet of the separator (6.1) is connected to the outlet of a similar material coal seam straight well, the gas outlet is connected to the gas collection bottle (6.7), the liquid outlet and the solid outlet are respectively connected to the electronic balance weighing device 1 (6.4) and the electronic balance weighing device 2 ( 6.5) Connect, and a gas flow meter (6.3) is provided on the communication line between the gas-liquid-solid separator (6.1) and the gas collection bottle (6.7);

   The data acquisition and control subsystem includes acquisition hardware and data processing software. The hardware includes a workstation, printer, and acquisition card. The acquisition card is composed of PCI8360 and CP-168; the software is used for parameter setting, control, and real-time data display of each component , And process the collected data to obtain data reports and graphs and generate a test database.
2. The simulation test system for pressure relief mining of cavern making caverns in coal-bed methane horizontal wells according to claim 1, characterized in that the simulation test system further includes a vacuum pump (5), a vacuum pump (5) and a coal seam of similar material The outlet pipeline of the vertical well is connected.
3. A simulation test system for pressure relief mining of a coal-bed methane horizontal well collapse hole making cave according to claim 1 or 2, wherein the pressure pulsation excitation pressure relief simulation subsystem further includes an abrasive tank (2.11) and a mixing The chamber (2.13), the outlet of the abrasive tank (2.11) and the outlet of the impact pressure chamber (2.7) communicate with the mixing chamber (2.13), and the outlet of the mixing chamber (2.13) communicates with the downhole injection device.
4. A simulation test system for pressure relief mining of collapsed holes in a coal-bed methane horizontal well according to claim 3, wherein the gas injection device further includes a gas storage tank (1.8), a one-way valve (1.11) and Pressure regulating valve (1.13), the inlet of the gas storage tank (1.8) communicates with the outlet of the booster pump (1.7); the check valve (1.11) is located between the gas mass flow controller (1.10) and the pressure sensor one (1.12) In the meantime, its outlet faces the pressure sensor one (1.12); the pressure regulating valve (1.13) is set at the outlet of the air compressor (1.6).
5. A simulation test system for pressure relief mining of cavern-making caverns in coal-bed methane horizontal wells according to claim 4, characterized in that the pressure pulsation excitation pressure relief simulation subsystem further includes a constant-speed constant-pressure pump (2.10) and The intermediate container (2.9), the inlet of the intermediate container (2.9) communicates with the constant speed and constant pressure pump (2.10), and the outlet of the intermediate container (2.9) communicates with the outlet pipeline of the impact pressure chamber (2.7).
6. A simulation test system for pressure relief mining of a coal-bed methane horizontal well collapse hole making cave according to claim 5, characterized in that: the output separation detection subsystem further includes a dryer (6.2), the dryer is located at Between the gas-liquid-solid separator (6.1) and the gas flow meter (6.3).
7. A simulation test system for pressure relief production of cavern-making caverns in coal-bed methane horizontal wells according to claim 6, characterized in that: high-pressure helium gas cylinders (1.1), carbon dioxide high-pressure gas cylinders (1.2) and methane high-pressure gas cylinders (1.3) The outlet pipeline is equipped with pressure gauge one (1.41), pressure gauge two (1.42) and pressure gauge three (1.43), which is connected to the pipeline between the air compressor (1.6) and the booster pump (1.7) There is a pressure gauge four (1.44), a pressure gauge five (1.45) on the inlet pipeline of the gas storage tank (1.8), and a pressure gauge six (1.46) on the inlet pipeline of the gas mass flow controller (1.10) .
8. A coal bed methane horizontal well collapse hole cavern pressure relief mining simulation test system according to claim 7, characterized in that: the coal system stratum structure reconstruction and similar material simulation subsystem further includes X direction displacement sensor ( 4.42), Y-direction displacement sensor (4.43) and Z-direction displacement sensor (4.41) are respectively set on the corresponding plugging piston.
9. A simulation test system for pressure relief mining of collapsed holes in coal-bed methane horizontal wells according to claim 8, characterized in that the strain measuring instrument is a distributed optical fiber measuring instrument, which is along the horizontal well level in coal seams of similar materials Segment direction distribution.

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