CN107255700B

CN107255700B - Coal bed gas well discharge and production process pulverized coal output simulation test device and test method thereof

Info

Publication number: CN107255700B
Application number: CN201710682211.1A
Authority: CN
Inventors: 倪小明; 李志恒; 金毅; 林俊峰; 张洲
Original assignee: Henan University of Technology
Current assignee: Henan University of Technology
Priority date: 2017-08-10
Filing date: 2017-08-10
Publication date: 2023-03-24
Anticipated expiration: 2037-08-10
Also published as: CN107255700A

Abstract

The coal-bed gas well discharge and production process pulverized coal output simulation test device comprises a discharge and production stage simulation system, a confining pressure control system, a pulverized coal test system and a key parameter control system, wherein an outlet of the discharge and production stage simulation system is connected with an inlet of the pulverized coal test system through a pipeline, a liquid outlet end of the confining pressure control system is connected with a liquid inlet end of the pulverized coal test system through a pipeline, and the key parameter control system is respectively connected with the discharge and production stage simulation system, the confining pressure control system and the pulverized coal test system through data lines. The invention also comprises a coal fracture development manufacturing model for manufacturing the rock core sample, wherein the coal fracture development manufacturing model comprises a columnar shell and a steel fracture template. The device can simulate the development conditions of fractures of different coal seams, obtains the influence of various key parameters on the output of the pulverized coal under different conditions by simulating the conditions of an on-site coal reservoir and the external environment conditions, and provides more reliable theoretical basis and reference for an on-site drainage and mining working system.

Description

Coal bed gas well discharge and production process pulverized coal output simulation test device and test method thereof

Technical Field

The invention belongs to the technical field of coal mine safety, and particularly relates to a simulation test device and a test method for coal powder output in a coal bed gas well drainage and production process.

Background

The ground coal bed gas well is produced by desorbing coal bed gas mainly through drainage-depressurization. The discharging and mining stages are different, and the main control factors of the coal powder output are different. In the single-phase water flow drainage and mining stage, the coal bed is mainly subjected to the scouring action of water flow, and if the drainage and mining strength is too high, the water yield is too high, so that the coal powder can be moved to a shaft along the fracture of the coal bed. On one hand, the coal powder output can increase the width of the coal seam crack; on the other hand, due to the lack of the support of the pulverized coal, the width of the crack of the coal seam is reduced under the action of the gravity and horizontal stress of surrounding rocks. Under the dual action, the difference of the deformation degree causes the relationship between the coal powder output and the permeability in the drainage stage to become complicated. When the coal reservoir enters a gas production stage, the pressure and impulsive force of free gas can enable coal dust in the coal seam to be further produced, and the permeability of the coal reservoir is related to the coal dust output, gas desorption and effective stress, so that the relationship between the coal dust output and the permeability is more complex. The coal powder output is not only related to the water yield, the gas yield and the like, but also related to the width, the length, the density, the shape and the like of the crack of the coal bed, and the difference of the crack development degree of the coal bed also has important influence on the water yield and the gas yield.

In order to find out the relation between the coal powder output and the pressure difference, the water quantity, the gas quantity and the like in different discharge and extraction stages of the coal bed gas well, researchers at home and abroad simulate the stress environment of the coal bed by drilling a coal pillar, placing the coal pillar in a three-shaft clamp, and setting different confining pressure and shaft pressure to test the coal powder output under different pressure differences. Because of the limitation of the selected coal sample, the fracture development degree of the selected coal sample is not clear, so that the research on the coal dust output is more based on the macroscopic aspect, the research is insufficient in the aspects of fine description such as flow, pressure difference and fracture development degree, and specific answers cannot be given to the discharge and mining working system of what kind needs to be adopted in different discharge and mining stages of what kind of coal reservoir. Some researchers adopt to make coal plates, clamp propping agents, coal dust and the like in the coal plates to test the output of the propping agents and the coal dust under certain pressure difference and flow, and obtain the relation by constructing a corresponding mathematical model. In order to better obtain the coal powder output of the coal-bed gas well under different conditions such as water yield, coal-bed fracture development degree, gas yield and gas/water mixing in different drainage and mining stages so as to provide guidance for the drainage and mining of the coal-bed gas well under different reservoir conditions on site, an apparatus is urgently needed, which can simulate different crack forms, can also simulate the stress state borne by the coal bed, test the coal powder output in different drainage and mining stages and more scientifically and effectively guide the formulation of a drainage and mining system of the coal-bed gas well.

Disclosure of Invention

Aiming at the fact that the existing different coal reservoir fracture pressure difference, water yield, gas yield and coal dust output are unknown and the field coal bed gas drainage and production cannot be really guided, a device capable of simulating the development conditions of different coal reservoir fractures is designed, the influence of various key parameters under different conditions on the coal dust output is obtained by simulating the field coal reservoir conditions and the external environment conditions, and more reliable theoretical basis and reference are provided for the field drainage and production working system.

In order to solve the technical problems, the invention adopts the following technical scheme: the coal-bed gas well discharge and production process pulverized coal output simulation test device comprises a discharge and production stage simulation system, a confining pressure control system, a pulverized coal test system and a key parameter control system, wherein an outlet of the discharge and production stage simulation system is connected with an inlet of the pulverized coal test system through a pipeline, a liquid outlet end of the confining pressure control system is connected with a liquid inlet end of the pulverized coal test system through a pipeline, and the key parameter control system is respectively connected with the discharge and production stage simulation system, the confining pressure control system and the pulverized coal test system through data lines.

The discharge and production stage simulation system comprises a gas phase simulation device, a liquid phase simulation device and a gas-liquid mixing device,

the gas phase simulation device comprises a high-pressure gas cylinder group and a first gas pressurization group,

the high-pressure gas cylinder group comprises a plurality of high-pressure gas cylinders, each high-pressure gas cylinder is connected with the gas inlet end of the first supercharging gas inlet pipe after being connected in parallel through a first high-pressure gas pipe, and each first high-pressure gas pipe is provided with a pressure reducing valve adjacent to the high-pressure gas cylinder;

the first gas pressurizing group comprises a plurality of gas pressurizing devices and a plurality of driving devices, the driving devices are matched with the gas pressurizing devices, the gas pressurizing devices are connected through pressurizing connecting pipes, the structures of the gas pressurizing devices are the same, each first gas pressurizing device comprises a first gas pressurizing chamber and a first high-pressure gas storage chamber, the first gas pressurizing chamber is connected with a high-pressure gas bottle through a first pressurizing gas inlet pipe and a first high-pressure gas pipe, a first one-way valve adjacent to the first gas pressurizing chamber is arranged on the first pressurizing gas inlet pipe, the first gas pressurizing chamber is connected with the high-pressure gas storage chamber through a second high-pressure gas pipe, a second one-way valve adjacent to the first gas pressurizing chamber and a third one-way valve adjacent to the first high-pressure gas storage chamber are respectively arranged on the second high-pressure gas pipe, a gas pressurizing piston is connected in the first gas pressurizing chamber in a sliding mode, and a piston rod is fixedly connected to the gas pressurizing piston; the pressure-increasing connecting pipe is provided with an automatic gas pressure-increasing control valve adjacent to the first high-pressure gas storage chamber;

the driving device comprises a first motor, a rotary table and a rotary rod, wherein a power output shaft of the first motor is in transmission connection with the rotary table, a hinge block is fixedly connected to the edge of the rotary table, one end of the rotary rod is hinged to the hinge block through a pin shaft, and the other end of the rotary rod is hinged to the piston rod through a pin shaft;

the second high-pressure air storage chamber in the first gas pressurization group is connected with the gas-liquid mixing device through a first pressurization air outlet pipe, and a first automatic control valve adjacent to the second high-pressure air storage chamber is arranged on the first pressurization air outlet pipe;

the liquid phase simulation device comprises a second gas pressurization group and a liquid pressurization group, the second gas pressurization group and the first gas pressurization group are same in structure, a gas pressurization chamber in the second gas pressurization group is communicated with the atmosphere through a second pressurization gas inlet pipe, a high-pressure gas storage chamber in the second gas pressurization group is connected with a first gas pipe of the liquid pressurization group through a second pressurization gas outlet pipe, a first pressure gauge is arranged on the first gas pipe, the liquid pressurization group comprises a plurality of hydraulic cylinders, liquid pressurization pistons are connected in the hydraulic cylinders in a sliding mode, the hydraulic cylinders are divided into gas cavities and liquid cavities by the liquid pressurization pistons, one ends of the gas cavities of the hydraulic cylinders are connected in parallel through the second gas pipes and then connected with the first gas pipe, second automatic control valves adjacent to the hydraulic cylinders are respectively arranged on the second gas pipes, one ends of the liquid cavities of the hydraulic cylinders are connected in parallel through the first high-pressure water pipes and then connected with the second high-pressure water pipes, and third automatic control valves adjacent to the hydraulic cylinders are respectively arranged on the first high-pressure water pipes;

the hydraulic cylinder is connected with the gas-liquid mixing device through a first high-pressure water pipe and a second high-pressure water pipe;

the gas-liquid mixing device comprises a reservoir cylinder, a second pressure gauge is arranged on the inner wall of the reservoir cylinder,

a first pressurization gas outlet pipe in the gas phase simulation device is connected with the reservoir cylinder, and a fourth automatic control valve adjacent to the reservoir cylinder and a third pressure gauge adjacent to the reservoir cylinder are arranged on the first pressurization gas outlet pipe;

a second high-pressure water pipe in the liquid phase simulation device is connected with the reservoir cylinder, and a fifth automatic control valve adjacent to the reservoir cylinder and a water pressure gauge adjacent to the reservoir cylinder are arranged on the second high-pressure water pipe;

the reservoir cylinder is connected with the pulverized coal testing system through a gas-liquid two-phase pipeline, and a sixth automatic control valve adjacent to the reservoir cylinder and a fourth pressure gauge adjacent to the reservoir cylinder are arranged on the gas-liquid two-phase pipeline.

The confining pressure control system comprises a first booster pump, a second booster pump and a third booster pump which have the same structure, the first booster pump, the second booster pump and the third booster pump are respectively provided with a second motor in a matching way,

the first booster pump, the second booster pump and the third booster pump respectively comprise a pump body, a booster base plate, a confining pressure boosting piston, a guide rail, a manual rotary table, a driven wheel, a driving shaft, a driven shaft, a threaded sleeve, a baffle plate, a laser range finder and a hydraulic pipe, wherein the pump body is cylindrical in appearance, the confining pressure boosting piston is slidably connected in the pump body and divides the interior of the pump body into a fracturing liquid cavity and a driving cavity;

the laser range finder is arranged on the base plate of the supercharger and is connected with the first concentrator through a data line; the second motor is connected with the first concentrator through a data line, a power output shaft of the second motor is in transmission connection with a driving wheel, the driving wheel is in transmission connection with a driven wheel through a belt, and the first concentrator is connected with the key parameter control system through a data line; the pump body has seted up on the inner wall of fracturing fluid chamber one end and has filled the liquid mouth, fills the spiro union on the liquid mouth and has connect the sealing plug, and the fracturing fluid chamber of the pump body passes through the hydraulic pressure pipe to be connected with buggy test system, is equipped with the fifth manometer on the hydraulic pressure pipe, and the fifth manometer passes through the data line with first concentrator and is connected.

The pulverized coal testing system comprises a clamping bracket, a clamping shell, a first core cushion block, a second core cushion block, a rubber sleeve, a powder discharge pipeline, a laser particle size analyzer and a pulverized coal sieve,

the core sample is arranged in the clamping shell, the clamping shell is horizontally fixed on the clamping support along the axial direction, the outline of a first core cushion block is cylindrical, the first core cushion block is divided into a gas-liquid two-phase inlet part and a gas-liquid two-phase outlet part, the gas-liquid two-phase inlet part is solid, an air inlet long hole is arranged at the axial center part, the gas-liquid two-phase outlet part comprises a plurality of concentric rings, a diffusion cavity is enclosed between every two adjacent concentric rings, each diffusion cavity is communicated with the air inlet long hole, a first cushion block mounting hole is arranged at the inlet end of the clamping shell, a second cushion block mounting hole is arranged at the outlet end of the clamping shell, the second cushion block mounting hole is provided with two symmetrical cushion block mounting grooves along the radial direction on the end face of the outlet end of the clamping shell, one side of the clamping shell close to the inlet end is fixedly connected with a first annular supporting seat along the axial direction, one side of the clamping shell close to the outlet end is fixedly connected with a second annular supporting seat along the circumferential direction, a rock sample placing cavity is arranged between the first annular supporting seat and the second annular supporting seat, the rubber sleeve is of an annular structure with the inner diameter matched with the diameter of a rock core sample, the length of the rubber sleeve is greater than that of the rock core sample, the rubber sleeve filled with the rock core sample is axially arranged on the first annular supporting seat and the second annular supporting seat,

the first core cushion block sequentially penetrates through the first cushion block mounting hole and the first annular supporting seat from outside to inside and then is abutted against one end of the core, an annular piston is sleeved outside the first core cushion block and is axially and slidably connected in the clamping shell, an axial pressurizing chamber is arranged between the inner wall of the inlet end of the clamping shell and the annular piston, an axial pressure reducing chamber is arranged between the annular piston and the first annular supporting seat, a confining pressure pressurizing chamber is arranged between the rubber sleeve and the inner wall of the rock sample placing cavity,

the second core cushion block comprises a cylindrical main body and two mounting lugs symmetrically arranged on the cylindrical main body along the radial direction, the mounting lugs are matched with the size of the cushion block mounting groove, a plurality of sieve meshes penetrating through the cylindrical main body are uniformly distributed on the cylindrical main body along the axial direction, the second core cushion block sequentially penetrates through the second cushion block mounting hole and the second annular supporting seat from outside to inside and then is abutted against the other end of the core, the mounting lugs of the second core cushion block are clamped on the inner wall of the outlet end of the clamping shell,

the buggy sieve sets up the outlet side at centre gripping shell, the exit end of second rock core cushion and buggy sieve are through arranging the powder pipeline intercommunication, it is equipped with the laser particle size ware to arrange the powder pipeline, the laser particle size ware passes through the data line with key parameter control system and is connected, the reservoir jar passes through the double-phase pipeline of gas-liquid and is connected with the slot hole that admits air, be equipped with the flowmeter on the double-phase pipeline of gas-liquid, the flowmeter passes through the data line with key parameter control system and is connected, the hydraulic pressure pipe intercommunication of axial pressure boost cavity and first booster pump, the hydraulic pressure pipe intercommunication of axial pressure reduction cavity and second booster pump, the hydraulic pressure pipe intercommunication of confined pressure boost cavity and third booster pump.

The key parameter control system comprises a computer and a workbench, the computer is installed on the workbench, and the computer is respectively connected with a first motor, a gas pressurization automatic control valve, a first automatic control valve, a second automatic control valve, a third automatic control valve, a fourth automatic control valve, a fifth automatic control valve, a sixth automatic control valve, a first pressure gauge, a second pressure gauge, a third pressure gauge, a fourth pressure gauge, a water pressure gauge, a first concentrator, a laser graduator and a flowmeter in the drainage and production stage simulation system, the confining pressure control system and the pulverized coal testing system through data lines.

The coal fracture development manufacturing model comprises a cylindrical shell and a steel fracture template, the cylindrical shell is of a cylindrical structure formed by two semicircular plates in a surrounding mode, a fastening ring is sleeved outside the cylindrical shell, the steel fracture template comprises a handle and a fracture template, the length of the fracture template is matched with that of the cylindrical shell, and the steel fracture template is made of steel plates.

The crack width of the crack template is divided into 1mm and 10mm, the crack form of the crack template comprises a straight crack form, a wave crack form, a net crack form, a tree fork crack form and a fishbone crack form, the straight crack form is formed by uniformly arranging straight strip plates arranged along the axial direction of a columnar shell at intervals along the radial direction of the columnar shell, the wave crack form is formed by uniformly arranging wave strip plates arranged along the axial direction of the columnar shell at intervals along the radial direction of the columnar shell, the net crack form is formed by net plates which are crossed obliquely, the tree fork crack form is formed by branch branches arranged along the axial direction, and the fishbone crack form is formed by uniformly arranging a plurality of fishbone branches arranged along the radial direction of the columnar shell at intervals along the axial direction of the columnar shell.

The testing method of the device for simulating and testing the coal powder output in the coal bed gas well drainage and production process comprises the following steps:

(1) And preparing an experimental sample:

selecting different coal rank coal samples in different blocks according to experimental requirements, crushing the coal samples, and screening coal dust with different particle sizes; proportioning the materials with similar materials according to different particle size ratios, manufacturing a rock core sample by using a coal fracture development manufacturing model, maintaining and polishing the sample;

(2) And testing the mechanical property of the core:

classifying the prepared different columnar core samples according to fracture types, and selecting a plurality of samples in each group for mechanical property testing; testing rock mechanical properties of the coal sample on an electronic universal pressure tester to obtain rock mechanical property parameters such as uniaxial compressive strength, elastic modulus, apparent density ratio and the like of the coal sample, and analyzing whether a rock core sample meets experimental requirements or not;

(3) Assembling experimental device and air tightness detection

Connecting all experimental devices and pipelines, sealing the pipelines, checking the communication condition of the pulverized coal testing system, injecting water into the experimental devices, detecting the air tightness of the experimental devices, and preparing for experiments;

(4) Experimental grouping and testing

Grouping and numbering the manufactured core samples according to different crack types and crushed coal collection areas, putting the different core samples into a clamping shell for experiment and collecting produced coal dust during test, drying, testing the particle size and mass content of the coal dust, and analyzing the coal dust output characteristics of cracks in the core samples under different scales and forms; combining parameters such as gas-liquid ratio, fluid pressure and the like in the two-phase flow in the experiment, recording and analyzing the coal powder particle size and the coal powder amount under different fluid conditions, gas-liquid ratios, crack forms and sizes;

(5) And comprehensive research

The method comprises the steps of setting different gas-liquid ratios and different pressures through a key parameter control system, manufacturing a crack distribution core model, simulating the change of bottom hole flow pressure in the discharging and mining process and combining with an experiment group, testing the coal powder output quantity and the output particle size when the size and the shape of cracks are changed in different discharging and mining stages and under the action of different confining pressures, testing the mineral content in the coal powder, combining with pressure parameters, analyzing the influence of the shape and the size of the cracks on the discharging and mining process, and researching the coal powder output rule aiming at different crack shapes in different discharging and mining stages.

The specific steps for preparing the experimental sample in the step (1) are as follows: the method comprises the steps of adopting gypsum and crushed coal with the particle size of 0.18-0.85mm as aggregate of similar materials of a coal reservoir, adopting portland cement as a cementing agent, adopting active carbon, water and sand with the particle size of 0.45-0.85mm as auxiliary materials, directly adopting crushed coal cementing and compression molding during low confining pressure simulation, designing different mass ratios according to different cement proportions during high confining pressure, preparing raw materials, sequentially adding the crushed coal, the gypsum, the cement and the water during core manufacturing, placing pasty materials in a columnar shell, respectively placing a straight slit type crack template, a wave slit type crack template, a net slit type crack template, a tree fork slit type crack template and a fish bone slit type crack template at the central position of the columnar shell, performing cementing molding, pressing on a pressing machine after molding to respectively obtain a straight slit type core sample, a wave slit type core sample, a net slit type core sample, a tree fork slit type core sample and a fish bone slit type sample, and taking out a steel crack template after alternate days of maintenance.

The concrete steps of putting the core sample into the clamping shell for experiment and collecting the produced coal dust in the step (4) are as follows:

a) After the core sample is sleeved in the rubber sleeve, the core sample is loaded into the clamping shell through the second cushion block mounting hole and is axially mounted on the first annular supporting seat and the second annular supporting seat, the second core cushion block is loaded into the clamping shell from the second cushion block mounting hole and then rotates by 90 degrees, the mounting lug of the second core cushion block is ensured to be clamped on the inner wall of the outlet end of the clamping shell, and two end parts of the core sample are respectively abutted against the first core cushion block and the second core cushion block;

b) The computer controls the simulation system to start working at the drainage and production stage, when the gas phase simulation device works, a high-pressure gas cylinder leads gas into a first high-pressure gas pipe and a first pressurization gas inlet pipe through a pressure reducing valve, the gas enters a gas pressurization chamber through a first one-way valve, a first motor drives a rotating rod to move through rotation, the rotating rod drives a gas pressurization piston to reciprocate in the gas pressurization chamber, the first one-way valve is closed, a second one-way valve and a third one-way valve are opened, the high-pressure gas enters a high-pressure gas storage chamber, the gas pressurization automatic control valve is in a closed state, after the high-pressure gas storage chamber reaches certain pressure through multiple operations, the computer controls the gas pressurization automatic control valve to be opened to enable the high-pressure gas to enter the second gas pressurization chamber and to be pressurized into the second high-pressure gas storage chamber through the gas pressurization piston again, and when an experiment starts, the high-pressure gas enters a storage cylinder through the first pressurization gas outlet pipe to provide a gas source; when the liquid phase simulation device works, the liquid pressurization group is pressurized through the second gas pressurization group, certain pressure is kept, the power pressure is controlled through the first pressure gauge, the second automatic control valve is controlled to be opened by the computer, high-pressure gas enters the gas cavity of the hydraulic cylinder after passing through the first gas pipe and the second gas pipe, the liquid pressurization piston is pushed to pressurize liquid in the liquid cavity, the pressure value is fed back to the computer through the first pressure gauge to be recorded, when the pressure reaches the experimental pressure, the computer controls the third automatic control valve to be opened, and high-pressure water enters the reservoir cylinder through the first high-pressure water pipe and the second high-pressure water pipe to provide a water source; when the gas-liquid mixing device works, a gas source enters the reservoir cylinder from the first pressure-increasing gas outlet pipe through the fourth automatic control valve, a water source enters the reservoir cylinder through the second high-pressure water pipe through the fifth automatic control valve, the gas-liquid ratio and the pressure are adjusted through the fourth automatic control valve and the fifth automatic control valve, and the experimental conditions of unidirectional flow and gas-water two-phase flow are simulated;

c) Meanwhile, the computer controls the confining pressure simulation system to start working, the computer controls the second motors of the first booster pump and the third booster pump to start, the driving shaft is driven to rotate, the driving shaft is transmitted to the driven shaft through the threaded sleeve, the baffle plate is pushed to move along the guide rail, the confining pressure boosting piston is pushed to move to enable fracturing fluid to enter a hydraulic pipe for boosting, and when the pressure reaches a set pressure, the fifth pressure gauge feeds back the fracturing fluid to the computer to stop boosting; the first booster pump injects high-pressure liquid into the axial boosting cavity through the hydraulic pipe to carry out axial boosting, and meanwhile, the third booster pump increases confining pressure to the confining pressure boosting cavity through the hydraulic pipe to simulate the formation pressure condition and carry out experiments;

d) The core sample is clamped by a first core cushion block and a second core cushion block, fluid in a storage cylinder enters the first core cushion block in a coal powder testing system through a gas-liquid two-phase pipeline, the core sample is tested, formed coal powder flows out of a sieve mesh of the second core cushion block, the coal powder passes through a coal powder channel, a laser particle size tester tests the particle size of the coal powder, the coal powder is filtered through a coal powder sieve and weighed to determine the mass of the coal powder, and a computer collects data of the particle size of the coal powder by collecting particle size distribution data in the laser particle size tester;

e) After the experiment is finished, the second motor of the second booster pump is controlled by the computer to be started, the second booster pump boosts the axial pressure reduction chamber, and meanwhile, the second motor of the first booster pump and the second motor of the third booster pump are controlled by the computer to rotate reversely to unload the pressure.

By adopting the technical scheme, the invention has the following advantages:

different drainage and production stages are simulated by changing the states of water, gas and water/gas in the drainage and production process, and the reservoir fluid change in the drainage and production process is represented to the maximum extent. The confining pressure simulation system realizes automatic pressurization by simultaneously controlling the axial direction and the radial direction of the rock core, and simulates the pressure condition of a coal reservoir. The coal crack development manufacturing model is formed by pressing similar materials in different proportions through a mould, the crack form distribution of a coal reservoir is simulated, a rock core sample is manufactured, and the rock core sample is loaded into a holder for testing. The coal powder testing system tests the coal powder migration output condition under different conditions by simulating rock cores with different fracture forms, and tests the coal powder particle size and the output quantity. The key parameter control system is calculated and fed back to the corresponding control equipment through software to regulate and control corresponding parameters.

The invention can simulate the development degrees of different coal bed fractures on site to the maximum extent through the coal fracture development model, and provides important guarantee for determining the relationship between the parameters such as gas production, water production, pressure difference and the like and the coal dust amount with different particle sizes in the drainage and production process of the coal bed gas well; the invention can simulate the fluid change state in the coal reservoir in the field discharge and mining process through the discharge and mining stage simulation system, test and analyze the coal powder yield under different fracture forms, and provide theoretical guidance for the discharge and mining working system formulation of different discharge and mining stages.

Drawings

FIG. 1 is a schematic structural view of the present invention;

FIG. 2 is a schematic diagram of the configuration of the drainage and mining phase simulation system of the present invention;

FIG. 3 is a schematic structural diagram of a confining pressure simulation system according to the present invention;

FIG. 4 is a schematic structural diagram of a pulverized coal testing system according to the present invention;

FIG. 5 is an outer structural view of the first core pad of FIG. 4;

FIG. 6 is a schematic view of an inner side structure of the first core pad of FIG. 4;

FIG. 7 is an outer structural view of the second core pad of FIG. 4;

FIG. 8 is a schematic view of the outlet end face of the clamp housing of FIG. 4;

FIG. 9 is a schematic structural diagram of a cylindrical shell in a model for coal fracture development in the present invention;

FIG. 10 is a schematic cross-sectional view of FIG. 9;

FIG. 11 is a schematic structural view of a straight slit type fracture template;

FIG. 12 is a schematic structural view of a wave-seam type fracture template;

FIG. 13 is a schematic view of the structure of a mesh slit-type template;

FIG. 14 is a schematic structural view of a crotch seam type split template;

FIG. 15 is a schematic structural view of a fishbone seam type fracture template;

FIG. 16 is a schematic structural view of a fabricated straight slit core sample;

FIG. 17 is a schematic structural diagram of a fabricated wavy seam type core sample;

FIG. 18 is a schematic structural view of a fabricated reticulated slit-type core sample;

FIG. 19 is a schematic structural view of a manufactured core sample of a tree-slit type;

fig. 20 is a schematic structural view of the prepared fishbone-stitched core sample.

Detailed Description

As shown in fig. 1 to 20, the coal powder output simulation test device for the coal bed gas well in the discharging and mining process comprises a discharging and mining stage simulation system i, a confining pressure simulation system ii, a coal powder test system iv and a key parameter control system v, wherein an outlet of the discharging and mining stage simulation system i is connected with an inlet of the coal powder test system iv through a pipeline, a liquid outlet end of the confining pressure simulation system ii is connected with a liquid inlet end of the coal powder test system iv through a pipeline, and the key parameter control system v is respectively connected with the discharging and mining stage simulation system i, the confining pressure simulation system ii and the coal powder test system iv through data lines.

The drainage and mining stage simulation system I comprises a gas phase simulation device 100, a liquid phase simulation device 200 and a gas-liquid mixing device 300,

the gas phase simulation apparatus 100 includes a high pressure gas cylinder set and a first gas pressurizing set,

the high-pressure gas cylinder group comprises a plurality of high-pressure gas cylinders 1, each high-pressure gas cylinder 1 is connected with the gas inlet end of the first pressurizing gas inlet pipe 401 after being connected in parallel through a first high-pressure gas pipe 101, and each first high-pressure gas pipe 101 is provided with a pressure reducing valve 2 adjacent to the high-pressure gas cylinder 1;

the first gas pressurizing group comprises a plurality of gas pressurizing devices and a plurality of driving devices, the driving devices are matched with the gas pressurizing devices, the gas pressurizing devices are connected through pressurizing connecting pipes 131, the structures of the gas pressurizing devices are the same, each first gas pressurizing device comprises a first gas pressurizing chamber 4 and a first high-pressure gas storage chamber 12, the first gas pressurizing chamber 4 is connected with the high-pressure gas bottle 1 through a first pressurizing gas inlet pipe 401 and a first high-pressure gas pipe 101, a first one-way valve 3 adjacent to the first gas pressurizing chamber 4 is arranged on the first pressurizing gas inlet pipe 401, the first gas pressurizing chamber 4 is connected with the first high-pressure gas storage chamber 12 through a second high-pressure gas pipe 10, a second one-way valve 9 adjacent to the first gas pressurizing chamber 4 and a third one-way valve 11 adjacent to the first high-pressure gas storage chamber 12 are respectively arranged on the second high-pressure gas pipe 10, a gas pressurizing piston 5 is connected in the first gas pressurizing chamber 4 in a sliding mode, and a piston rod 501 is fixedly connected on the gas pressurizing piston 5; the automatic gas pressurization control valve 13 adjacent to the first high-pressure gas storage chamber 12 is arranged on the pressurization connecting pipe 131;

the driving device comprises a first motor 7, a driving turntable 6 and a rotating rod 8, wherein a power output shaft of the first motor 7 is in transmission connection with the driving turntable 6, the edge of the driving turntable 6 is fixedly connected with a hinge block 601, one end of the rotating rod 8 is hinged with the hinge block 601 through a pin shaft, and the other end of the rotating rod 8 is hinged with the piston rod 501 through a pin shaft;

the second high-pressure air storage chamber 15 in the first gas pressurization group is connected with the gas-liquid mixing device 300 through a first pressurization air outlet pipe 23, and a first automatic control valve 16 adjacent to the second high-pressure air storage chamber 15 is arranged on the first pressurization air outlet pipe 23;

the liquid phase simulation device 200 comprises a second gas pressurization group and a liquid pressurization group, the second gas pressurization group and the first gas pressurization group have the same structure, a gas pressurization chamber 172 in the second gas pressurization group is communicated with the atmosphere through a second pressurization gas inlet pipe 173, a high-pressure gas storage chamber 171 in the second gas pressurization group is connected with a first gas pipe 18 of the liquid pressurization group through a second pressurization gas outlet pipe 174, a first pressure gauge 17 is arranged on the first gas pipe 18, the liquid pressurization group comprises a plurality of hydraulic cylinders 19, liquid pressurization pistons 21 are slidably connected in the hydraulic cylinders 19, the liquid pressurization pistons 21 divide the interiors of the hydraulic cylinders 19 into gas cavities and liquid cavities, one ends of the gas cavities of the hydraulic cylinders 19 are connected with the first gas pipe 18 after being connected in parallel through second gas pipes 181, second automatic control valves 20 adjacent to the hydraulic cylinders 19 are respectively arranged on the second gas pipes 181, one ends of the liquid cavities of the hydraulic cylinders 19 are connected with the second high-pressure water pipes 31 after being connected in parallel through first high-pressure water pipes 191, and third automatic control valves 22 adjacent to the hydraulic cylinders 19 are respectively arranged on the first high-pressure water pipes 191;

the hydraulic cylinder 19 is connected with the gas-liquid mixing device 300 through a first high-pressure water pipe 191 and a second high-pressure water pipe 31;

the gas-liquid mixing device 300 includes a reservoir cylinder 27, a second pressure gauge 26 is installed on an inner wall of the reservoir cylinder 27,

a first pressurizing air outlet pipe 23 in the gas phase simulation device 100 is connected with the reservoir cylinder 27, and a fourth automatic control valve 24 adjacent to the reservoir cylinder 27 and a third pressure gauge 25 adjacent to the reservoir cylinder 27 are arranged on the first pressurizing air outlet pipe 23;

a second high-pressure water pipe 31 in the liquid phase simulation device 200 is connected with the reservoir cylinder 27, and a fifth automatic control valve 30 adjacent to the reservoir cylinder 27 and a water pressure gauge 32 adjacent to the reservoir cylinder 27 are arranged on the second high-pressure water pipe 31;

the reservoir cylinder 27 is connected with the pulverized coal testing system IV through a gas-liquid two-phase pipeline 51, and a sixth automatic control valve 28 adjacent to the reservoir cylinder 27 and a fourth pressure gauge 29 adjacent to the reservoir cylinder 27 are arranged on the gas-liquid two-phase pipeline 51.

The confining pressure simulation system II comprises a first booster pump 45, a second booster pump 46 and a third booster pump 47 which have the same structure, the first booster pump 45, the second booster pump 46 and the third booster pump 47 are respectively provided with a second motor 44 in a matching way,

the first booster pump 45, the second booster pump 46 and the third booster pump 47 all comprise a pump body 471, a booster base plate 35, a confining pressure boosting piston 38, a guide rail 37, a manual rotating disc 43, a driven wheel 441, a driving shaft 39, a driven shaft 40, a threaded sleeve 42, a baffle plate 41, a laser range finder 36 and a hydraulic pipe 34, the pump body 471 is cylindrical in shape, the confining pressure boosting piston 38 is slidably connected in the pump body 471, the confining pressure boosting piston 38 divides the interior of the pump body 471 into a fracturing liquid cavity and a driving cavity, the booster base plate 35 is fixedly connected at one end of the fracturing liquid cavity of the pump body 471, the guide rail 37 is arranged on two sides of the pump body 471, one end of the guide rail 37 is fixedly connected with the booster base plate 35, the axes of the guide rail 37 and the pump body 471 are located in the same plane, the manual rotating disc 43 is arranged on the outer side of one end of the driving cavity of the pump body 471, the manual rotating disc 43 is in transmission connection with the driving shaft 39, the driven wheel 441 is located on the inner side of the manual rotating disc 43 and is in transmission connection with the driving shaft 39, the driving shaft 39 is in transmission connection with the threaded sleeve 42 through a spiral protrusion arranged on the driving shaft 39 and a spiral groove arranged in the threaded sleeve 42, the baffle 41 is arranged between the pump body 471 and the threaded sleeve 42, two ends of the baffle 41 are inserted in the guide rail 37 and are in sliding connection with the guide rail 37, one end of the threaded sleeve 42 is fixedly connected with the baffle 41, the driving shaft 39 sequentially penetrates through the baffle 41 and the pump body 471 from outside to inside and extends into the driving cavity, the driven shaft 40 is of a hollow structure, the driven shaft 40 is sleeved outside the driving shaft 39, one end of the driven shaft 40 penetrates through the pump body 471 from outside to inside and is fixedly connected with the confining pressure boosting piston 38, and the other end of the driven shaft 40 is fixedly connected with the baffle 41;

the laser range finder 36 is mounted on the booster base plate 35 and connected with the first concentrator 48 through a data line, and the laser range finder 36 is used for measuring the distance between the baffle plate 41 and the booster base plate 35 and controlling the boosting rate of the booster pump according to the magnitude of the travel distance; the second motor 44 is connected with the first concentrator 48 through a data line, a driving wheel 441 is connected to a power output shaft of the second motor 44 in a transmission manner, the driving wheel 441 is connected with a driven wheel 441 in a transmission manner through a belt, and the first concentrator 48 is connected with the key parameter control system V through a data line; the pump body 471 is provided with a liquid filling port on the inner wall of one end of the fracturing liquid chamber, the liquid filling port is screwed with a sealing plug 49, the fracturing liquid chamber of the pump body 471 is connected with a pulverized coal testing system IV through a hydraulic pipe 34, the hydraulic pipe 34 is provided with a fifth pressure gauge 33, and the fifth pressure gauge 33 is connected with a first concentrator 48 through a data line.

The pulverized coal testing system IV comprises a clamping bracket 65, a clamping shell 54, a first core cushion block 53, a second core cushion block 61, a rubber sleeve 59, a powder discharging pipeline 62, a laser particle size instrument 63 and a pulverized coal sieve 64,

the holding shell 54 is of a cylindrical structure, a core sample 60 is arranged in the holding shell 54, the holding shell 54 is horizontally fixed on a holding bracket 65 along the axial direction, the outer contour of the first core cushion block 53 is cylindrical, the first core cushion block 53 is divided into a gas-liquid two-phase inlet part and a gas-liquid two-phase outlet part, the gas-liquid two-phase inlet part is solid, an air inlet long hole 531 is axially arranged at the axis, the gas-liquid two-phase outlet part comprises a plurality of concentric rings, a diffusion cavity 532 is enclosed between every two adjacent concentric rings, each diffusion cavity 532 is communicated with the air inlet long hole 531, a first cushion block mounting hole 541 is arranged at the inlet end of the holding shell 54, a second cushion block mounting hole 542 is arranged at the outlet end of the holding shell 54, two symmetrical cushion block mounting grooves 661 are radially arranged on the end face 66 of the holding shell 54, a first annular supporting seat 543 is fixedly connected to one side close to the inlet end along the axial direction in the holding shell 54, a second annular supporting seat 544 is fixedly connected to one side close to the outlet end in the holding shell 54 along the circumferential direction, a second annular supporting seat 544 is arranged between the first annular supporting seat 543, the first annular supporting seat 59 and the annular supporting seat is arranged on the annular supporting seat 59 of the annular structure of the core sample 59,

the first core cushion block 53 sequentially penetrates through the first cushion block mounting hole 541 and the first annular supporting seat 543 from outside to inside and then is abutted against one end of the core sample 60, an annular piston 56 is sleeved outside the first core cushion block 53, the annular piston 56 is axially and slidably connected in the clamping shell 54, an axial pressurizing chamber 55 is arranged between the inner wall of the inlet end of the clamping shell 54 and the annular piston 56, an axial pressure reducing chamber 57 is arranged between the annular piston 56 and the first annular supporting seat 543, and a confining pressure pressurizing chamber 58 is arranged between the rubber sleeve 59 and the inner wall of the rock sample placing cavity,

the second core cushion block 61 comprises a cylindrical main body and two mounting lugs 611 which are symmetrically arranged on the cylindrical main body along the radial direction, the mounting lugs 611 are matched with the cushion block mounting groove 661 in size, a plurality of sieve holes 612 which penetrate through the cylindrical main body are uniformly distributed on the cylindrical main body along the axial direction, the second core cushion block 61 sequentially penetrates through the second cushion block mounting hole 542 and the second annular supporting seat 544 from outside to inside and then is abutted against the other end of the core sample 60, the mounting lugs 611 of the second core cushion block 61 are clamped on the inner wall of the outlet end of the clamping shell 54, after the second core cushion block 61 is arranged in the clamping shell 54 from outside to inside, the second core cushion block 61 rotates 90 degrees, the mounting lugs 611 can be clamped on the inner wall of the outlet end of the clamping shell 54,

the pulverized coal screen 64 is arranged on the outlet side of the clamping shell 54, the outlet end of the second core cushion block 61 is communicated with the pulverized coal screen 64 through a pulverized coal discharging pipeline 62, a laser particle size instrument 63 is arranged on the pulverized coal discharging pipeline 62, the laser particle size instrument 63 is connected with a key parameter control system V through a data line, the reservoir cylinder 27 is connected with the air inlet long hole 531 through a gas-liquid two-phase pipeline 51, a flow meter 52 is arranged on the gas-liquid two-phase pipeline 51, the flow meter 52 is connected with the key parameter control system V through a data line, the axial pressurizing chamber 55 is communicated with the hydraulic pipe 34 of the first pressurizing pump 45, the axial pressure reducing chamber 57 is communicated with the hydraulic pipe 34 of the second pressurizing pump 46, and the confining pressure pressurizing chamber 58 is communicated with the hydraulic pipe 34 of the third pressurizing pump 47.

The key parameter control system V comprises a computer 67 and a workbench 68, the computer 67 is installed on the workbench 68, and the computer 67 is respectively connected with the first motor 7, the gas pressurization automatic control valve 13, the first automatic control valve 16, the second automatic control valve 20, the third automatic control valve 22, the fourth automatic control valve 24, the fifth automatic control valve 30, the sixth automatic control valve 28, the first pressure gauge 17, the second pressure gauge 26, the third pressure gauge 25, the fourth pressure gauge 29, the water pressure gauge 32, the first concentrator 48, the laser particle size analyzer 63 and the flow meter 52 in the drainage and production stage simulation system I, the confining pressure simulation system II and the coal powder test system IV through data lines.

The coal fracture development manufacturing model III is used for manufacturing the rock core sample 60 and comprises a cylindrical shell 70 and a steel fracture template, the cylindrical shell 70 is of a cylindrical structure formed by two semicircular plates in a surrounding mode, a fastening ring 71 is sleeved outside the cylindrical shell 70, the steel fracture template comprises a handle 73 and a fracture template 72, the length of the fracture template 72 is matched with that of the cylindrical shell 70, the steel fracture template is made of a steel plate, the steel plate is cold-work die steel, the hardness of the steel plate is high, and the die can be guaranteed not to change in shape due to external force and environmental change.

The crack width of the crack template 72 is divided into two types, namely 1mm and 10mm, the crack shape of the crack template 72 includes a straight crack type, a wave crack type, a net crack type, a tree-fork crack type and a fishbone crack type, the straight crack type crack template (as shown in fig. 11) is formed by uniformly arranging straight line strip plates along the axial direction of the columnar shell 70 at intervals along the radial direction of the columnar shell 70, the wave crack type crack template (as shown in fig. 12) is formed by uniformly arranging wave strip plates along the axial direction of the columnar shell 70 at intervals along the radial direction of the columnar shell 70, the net crack type crack template (as shown in fig. 13) is formed by uniformly arranging net plates in a cross shape, the tree-fork crack type crack template (as shown in fig. 14) is formed by uniformly arranging tree-fork branches along the axial direction, and the fishbone crack template (as shown in fig. 15) is formed by uniformly arranging a plurality of fishbone branches along the radial direction of the columnar shell 70 at intervals along the axial direction of the columnar shell 70.

(1) And preparing an experimental sample:

selecting different coal rank coal samples in different blocks according to experimental requirements, crushing the coal samples, and screening coal dust with different particle sizes; preparing a core sample 60 by using a coal fracture development preparation model III according to the proportion of different particle size and similar materials, maintaining and polishing the sample;

(2) And testing the mechanical property of the core:

classifying the prepared different columnar core samples 60 according to fracture types, and selecting a plurality of samples in each group for mechanical property testing; testing the rock mechanical properties of the coal sample on an electronic universal pressure tester to obtain rock mechanical property parameters such as uniaxial compressive strength, elastic modulus, apparent density ratio and the like of the coal sample, and analyzing whether the rock core sample 60 meets the experimental requirements or not;

(3) Assembling experimental device and air tightness detection

Connecting all the experimental devices and pipelines, sealing the pipelines, checking the communication condition of the pulverized coal testing system IV, detecting the air tightness of the experimental devices by injecting water into the experimental devices, and preparing to carry out experiments;

(4) Experimental grouping and testing

Grouping and numbering the manufactured core samples 60 according to different crack types and crushed coal collection areas, putting the different core samples 60 into the clamping shell 54 for experiment and collecting produced coal dust during testing, drying, testing the particle size and mass content of the coal dust, and analyzing the coal dust output characteristics of cracks in the core samples 60 under different scales and forms; combining parameters such as gas-liquid ratio, fluid pressure and the like in the two-phase flow in the experiment, recording and analyzing the coal powder particle size and the coal powder amount under different fluid conditions, gas-liquid ratios, crack forms and sizes;

(5) And comprehensive research

The method comprises the steps of setting different gas-liquid ratios and different pressures through a key parameter control system V, manufacturing a crack distribution core model, simulating bottom hole flow pressure change in the discharging and mining process to combine with experimental grouping, testing the coal powder output and output particle size and the mineral content in coal powder when the size and shape of cracks are changed in different discharging and mining stages and under the action of different confining pressures, analyzing the influence of the shape and size of the cracks on the discharging and mining process by combining with pressure parameters, and researching the coal powder output rule aiming at different crack shapes in different discharging and mining stages.

The specific steps for preparing the experimental sample in the step (1) are as follows: the method comprises the steps of adopting gypsum and crushed coal with the particle size of 0.18-0.85mm as aggregate of similar materials of a coal reservoir, adopting portland cement as a cementing agent, adopting 425 # common portland cement as the portland cement, adopting activated carbon, water and sand with the particle size of 0.45-0.85mm as auxiliary materials, directly adopting crushed coal for cementing and press forming during low ambient pressure simulation, designing different mass proportions according to different cement proportions during high ambient pressure, preparing raw materials, sequentially adding the crushed coal, the gypsum, the cement and the water during core manufacturing, placing pasty materials into a cylindrical shell 70, respectively placing a straight slit type crack template, a wave slit type crack template, a mesh slit type crack template, a fork slit type crack template and a fishbone slit type crack template at the central position of the cylindrical shell 70, carrying out cementing forming, carrying out press forming on a press machine after forming, respectively obtaining a straight slit type core sample (shown in a figure 16), a wave slit type core sample (shown in a figure 17), a mesh slit type core sample (shown in a figure 18), a fork slit type core sample (shown in a figure 19) and a fishbone seam type crack sample (shown in a figure 20), and carrying out maintenance and carrying out steel maintenance on a day.

The concrete steps of putting the core sample 60 into the clamping shell 54 for experiment and collecting the produced coal dust in the step (4) are as follows:

a) After the core sample 60 is sleeved into the rubber sleeve 59, the core sample is loaded into the clamping shell 54 through the second cushion block mounting hole 542 and is axially mounted on the first annular supporting seat 543 and the second annular supporting seat 544, the second core cushion block 61 is loaded into the clamping shell 54 from the second cushion block mounting hole 542 and rotates by 90 degrees again, the mounting lug 611 of the second core cushion block 61 is guaranteed to be clamped on the inner wall of the outlet end of the clamping shell 54, and two end parts of the core sample 60 are respectively abutted to the first core cushion block 53 and the second core cushion block 61;

b) When the gas phase simulation device 100 works, a high-pressure gas bottle 1 leads gas into a first high-pressure gas pipe 101 and a first pressurization gas inlet pipe 401 through a pressure reducing valve 2, the gas enters a gas pressurizing chamber 4 through a first one-way valve 3, a first motor 7 drives a rotating rod 8 to move through rotation, the rotating rod 8 drives a gas pressurizing piston 5 to reciprocate in the gas pressurizing chamber 4, the first one-way valve 3 is closed, a second one-way valve 9 and a third one-way valve 11 are opened, the high-pressure gas enters a high-pressure gas storage chamber 12, the gas pressurization automatic control valve 13 is in a closed state, after the high-pressure gas storage chamber 12 reaches certain pressure through multiple operations, the computer 67 controls the gas pressurization automatic control valve 13 to be opened, the high-pressure gas enters a second gas pressurizing chamber 14 of an adjacent gas pressurizing device and is pressurized and enters a second high-pressure gas storage chamber 15 through the gas pressurizing piston 5 again, and when an experiment starts, the high-pressure gas enters a storage cylinder 27 through a first pressurization gas outlet pipe 23 to provide a gas source; when the liquid phase simulation device 200 works, the liquid pressurization group is pressurized through the second gas pressurization group, certain pressure is kept, the power pressure is controlled through the first pressure gauge 17, the computer 67 controls the second automatic control valve 20 to be opened, high-pressure gas enters the gas cavity of the hydraulic cylinder 19 after passing through the first gas pipe 18 and the second gas pipe 181, the liquid pressurization piston 21 is pushed to pressurize liquid in the liquid cavity, the pressure value is fed back to the computer 67 through the first pressure gauge 17 to be recorded, when the pressure reaches the experimental pressure, the computer 67 controls the third automatic control valve 22 to be opened, and high-pressure water enters the reservoir cylinder 27 through the first high-pressure water pipe 191 and the second high-pressure water pipe 31 to provide water source; when the gas-liquid mixing device 300 works, a gas source enters the reservoir cylinder 27 from the first pressurization gas outlet pipe 23 through the fourth automatic control valve 24, a water source enters the reservoir cylinder 27 through the second high-pressure water pipe 31 through the fifth automatic control valve 30, the gas-liquid ratio and the pressure are adjusted through the fourth automatic control valve and the fifth automatic control valve 30, and the experimental conditions of unidirectional flow and gas-water two-phase flow are simulated;

c) Meanwhile, the computer 67 controls the confining pressure simulation system II to start working, the computer 67 controls the second motors 44 of the first pressurizing pump 45 and the third pressurizing pump 47 to start, drives the driving shaft 39 to rotate, transmits the rotation to the driven shaft 40 through the threaded sleeve 42, pushes the baffle plate 41 to move along the guide rail 37, pushes the confining pressure pressurizing piston 38 to move, enables the fracturing fluid to enter the hydraulic pipe 34 for pressurizing, and when the pressure reaches the set pressure, the fifth pressure gauge 33 feeds back the pressure to the computer 67 to stop pressurizing; the first booster pump 45 injects high-pressure liquid into the axial boosting chamber 55 through the hydraulic pipe 34 to carry out axial boosting, and meanwhile, the third booster pump 47 increases confining pressure to the confining pressure boosting chamber 58 through the hydraulic pipe 34 to simulate the formation pressure condition to carry out experiments;

d) The core sample 60 is clamped by a first core cushion block 53 and a second core cushion block 61, fluid in the reservoir cylinder 27 enters the first core cushion block 53 in the coal dust testing system IV through a gas-liquid two-phase pipeline 51, the core sample 60 is tested, formed coal dust flows out of a sieve mesh 612 of the second core cushion block 61 and passes through a coal dust channel, a laser particle size tester tests the particle size of the coal dust, the coal dust is filtered through a coal dust sieve 64 and weighed to determine the quality of the coal dust, and a computer 67 collects data of the particle size distribution data in the laser particle size tester 63;

e) After the experiment is finished, the computer 67 controls the second motor 44 of the second booster pump 46 to start, the second booster pump 46 boosts the pressure of the axial pressure reduction chamber 57, and simultaneously the computer 67 controls the second motors 44 of the first booster pump 45 and the third booster pump 47 to rotate reversely to unload the pressure.

The press, the laser sizer 63, and the pulverized coal screen 64 are conventional devices, and the detailed structure thereof will not be described in detail.

The present embodiment is not intended to limit the shape, material, structure, etc. of the present invention in any way, and any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention are all within the scope of the technical solution of the present invention.

Claims

1. Coal bed gas well row adopts process buggy output simulation test device, its characterized in that: the system comprises a discharge and mining stage simulation system, a confining pressure control system, a coal powder testing system and a key parameter control system, wherein an outlet of the discharge and mining stage simulation system is connected with an inlet of the coal powder testing system through a pipeline, a liquid outlet end of the confining pressure control system is connected with a liquid inlet end of the coal powder testing system through a pipeline, and the key parameter control system is respectively connected with the discharge and mining stage simulation system, the confining pressure control system and the coal powder testing system through data lines.

2. The coal bed gas well discharging and mining process pulverized coal output simulation test device according to claim 1, characterized in that: the discharge and production stage simulation system comprises a gas phase simulation device, a liquid phase simulation device and a gas-liquid mixing device,

3. The coal bed gas well discharging and mining process pulverized coal output simulation test device according to claim 2, characterized in that: the confining pressure control system comprises a first booster pump, a second booster pump and a third booster pump which have the same structure, the first booster pump, the second booster pump and the third booster pump are respectively provided with a second motor in a matching way,

4. The coal bed gas well discharging and mining process pulverized coal output simulation test device according to claim 3, characterized in that: the pulverized coal testing system comprises a clamping bracket, a clamping shell, a first core cushion block, a second core cushion block, a rubber sleeve, a powder discharge pipeline, a laser particle size analyzer and a pulverized coal sieve,

the core sample is arranged in the clamping shell, the clamping shell is horizontally fixed on the clamping support along the axial direction, the outline of a first core cushion block is cylindrical, the first core cushion block is divided into a gas-liquid two-phase inlet part and a gas-liquid two-phase outlet part, the gas-liquid two-phase inlet part is solid, an air inlet long hole is arranged at the axial center part, the gas-liquid two-phase outlet part comprises a plurality of concentric rings, a diffusion cavity is enclosed between every two adjacent concentric rings, each diffusion cavity is communicated with the air inlet long hole, a first cushion block mounting hole is arranged at the inlet end of the clamping shell, a second cushion block mounting hole is arranged at the outlet end of the clamping shell, the second cushion block mounting hole is radially provided with two symmetrical cushion block mounting grooves on the end face of the outlet end of the clamping shell, one side of the clamping shell close to the inlet end is fixedly connected with a first annular supporting seat along the axial direction, one side of the clamping shell close to the outlet end is fixedly connected with a second annular supporting seat along the circumferential direction, a rock sample placing cavity is arranged between the first annular supporting seat and the second annular supporting seat, the rubber sleeve is of an annular structure with the inner diameter matched with the diameter of a rock core sample, the length of the rubber sleeve is greater than that of the rock core sample, the rubber sleeve containing the rock core sample is axially arranged on the first annular supporting seat and the second annular supporting seat,

the second core cushion block comprises a cylindrical main body and two mounting lugs which are symmetrically arranged on the cylindrical main body along the radial direction, the mounting lugs are matched with the size of the cushion block mounting groove, a plurality of sieve pores which penetrate through the cylindrical main body are uniformly distributed on the cylindrical main body along the axial direction, the second core cushion block sequentially penetrates through the second cushion block mounting hole and the second annular supporting seat from outside to inside and then is abutted against the other end of the core, the mounting lugs of the second core cushion block are clamped on the inner wall of the outlet end of the clamping shell,

5. The coal bed gas well coal dust production simulation test device in the drainage and production process of the coal bed gas well according to claim 4, characterized in that: the key parameter control system comprises a computer and a workbench, the computer is installed on the workbench, and the computer is respectively connected with a first motor, a gas pressurization automatic control valve, a first automatic control valve, a second automatic control valve, a third automatic control valve, a fourth automatic control valve, a fifth automatic control valve, a sixth automatic control valve, a first pressure gauge, a second pressure gauge, a third pressure gauge, a fourth pressure gauge, a water pressure gauge, a first concentrator, a laser gradiometer and a flowmeter in the drainage and production stage simulation system, the confining pressure control system and the pulverized coal testing system through data lines.

6. The coal bed gas well discharging and mining process pulverized coal output simulation test device according to claim 5, characterized in that: the coal fracture development model comprises a cylindrical shell and a steel fracture template, the cylindrical shell is of a cylindrical structure formed by two semi-circular arc plates in a surrounding mode, a fastening circular ring is sleeved outside the cylindrical shell, the steel fracture template comprises a handle and a fracture template, the length of the fracture template is matched with that of the cylindrical shell, and the steel fracture template is made of steel plates.

7. The coal bed gas well discharging and mining process pulverized coal output simulation test device according to claim 6, characterized in that: the crack width of the crack template is divided into 1mm and 10mm, the crack form of the crack template comprises a straight crack form, a wave crack form, a net crack form, a tree fork crack form and a fishbone crack form, the straight crack form is formed by uniformly arranging straight strip plates arranged along the axial direction of a columnar shell at intervals along the radial direction of the columnar shell, the wave crack form is formed by uniformly arranging wave strip plates arranged along the axial direction of the columnar shell at intervals along the radial direction of the columnar shell, the net crack form is formed by net plates which are crossed obliquely, the tree fork crack form is formed by branch branches arranged along the axial direction, and the fishbone crack form is formed by uniformly arranging a plurality of fishbone branches arranged along the radial direction of the columnar shell at intervals along the axial direction of the columnar shell.

8. The testing method of the coal-bed gas well discharging and mining process pulverized coal output simulation testing device according to claim 7, characterized in that: the method comprises the following steps:

(1) And preparing an experimental sample:

selecting different coal rank coal samples in different blocks according to experimental requirements, crushing the coal samples, and screening coal dust with different particle sizes; matching with similar materials according to different particle size ratios, manufacturing a rock core sample by using a coal fracture development manufacturing model, maintaining and polishing the sample;

(2) And testing the mechanical property of the core:

(3) Assembling experimental device and air tightness detection

(4) Experimental grouping and testing

(5) And comprehensive research

The method comprises the steps of setting different gas-liquid ratios and different pressures through a key parameter control system, manufacturing a crack distribution core model, simulating bottom hole flow pressure change in the discharging and mining process to combine with experimental grouping, testing the coal powder output and output particle size and the mineral content in coal powder when the sizes and the shapes of cracks are changed in different discharging and mining stages and under the action of different confining pressures, analyzing the influence of the shapes and the sizes of the cracks on the discharging and mining process by combining with pressure parameters, and researching the coal powder output rule aiming at different discharging and mining stages and different crack shapes.

9. The testing method of the coal-bed gas well discharging and mining process pulverized coal output simulation testing device according to claim 8, characterized by comprising the following steps: the specific steps for preparing the experimental sample in the step (1) are as follows: the method comprises the steps of adopting gypsum and crushed coal with the particle size of 0.18-0.85mm as aggregate of similar materials of a coal reservoir, adopting portland cement as a cementing agent, adopting active carbon, water and sand with the particle size of 0.45-0.85mm as auxiliary materials, directly adopting crushed coal cementing and compression molding during low confining pressure simulation, designing different mass ratios according to different cement proportions during high confining pressure, preparing raw materials, sequentially adding the crushed coal, the gypsum, the cement and the water during core manufacturing, placing pasty materials in a columnar shell, respectively placing a straight slit type crack template, a wave slit type crack template, a net slit type crack template, a tree fork slit type crack template and a fish bone slit type crack template at the central position of the columnar shell, performing cementing molding, pressing on a pressing machine after molding to respectively obtain a straight slit type core sample, a wave slit type core sample, a net slit type core sample, a tree fork slit type core sample and a fish bone slit type sample, and taking out a steel crack template after alternate days of maintenance.

10. The testing method of the coal-bed gas well discharging and mining process pulverized coal output simulation testing device according to claim 8, characterized by comprising the following steps: the concrete steps of putting the core sample into the clamping shell for experiment and collecting the produced coal dust in the step (4) are as follows:

b) The computer controls the simulation system to start working at the drainage and production stage, when the gas phase simulation device works, a high-pressure gas cylinder leads gas into a first high-pressure gas pipe and a first pressurization gas inlet pipe through a pressure reducing valve, the gas enters a gas pressurization chamber through a first one-way valve, a first motor drives a rotating rod to move through rotation, the rotating rod drives a gas pressurization piston to reciprocate in the gas pressurization chamber, the first one-way valve is closed, a second one-way valve and a third one-way valve are opened, the high-pressure gas enters a high-pressure gas storage chamber, the gas pressurization automatic control valve is in a closed state, after the high-pressure gas storage chamber reaches certain pressure through multiple operations, the computer controls the gas pressurization automatic control valve to be opened to enable the high-pressure gas to enter the second gas pressurization chamber and to be pressurized into the second high-pressure gas storage chamber through the gas pressurization piston again, and when an experiment starts, the high-pressure gas enters a storage cylinder through the first pressurization gas outlet pipe to provide a gas source; when the liquid phase simulation device works, a liquid pressurization group is pressurized through a second gas pressurization group, certain pressure is kept, the power pressure is controlled through a first pressure gauge, a computer controls a second automatic control valve to be opened, high-pressure gas enters a gas cavity of a hydraulic cylinder after passing through a first gas pipe and a second gas pipe, a liquid pressurization piston is pushed to pressurize liquid in the liquid cavity, the pressure value is fed back to the computer through the first pressure gauge to record, when the pressure reaches an experimental pressure, the computer controls a third automatic control valve to be opened, and high-pressure water enters a reservoir cylinder through a first high-pressure water pipe and a second high-pressure water pipe to provide a water source; when the gas-liquid mixing device works, a gas source enters the reservoir cylinder from the first pressure-increasing gas outlet pipe through the fourth automatic control valve, a water source enters the reservoir cylinder through the second high-pressure water pipe through the fifth automatic control valve, the gas-liquid ratio and the pressure are adjusted through the fourth automatic control valve and the fifth automatic control valve, and the experimental conditions of unidirectional flow and gas-water two-phase flow are simulated;

d) The rock core sample is clamped by a first rock core cushion block and a second rock core cushion block, fluid in a storage cylinder enters the first rock core cushion block in a pulverized coal testing system through a gas-liquid two-phase pipeline, the rock core sample is tested, formed pulverized coal flows out of a sieve pore of the second rock core cushion block, a laser particle size tester tests the particle size of the pulverized coal through a pulverized coal channel, the pulverized coal is filtered through a pulverized coal sieve and weighed to determine the mass of the pulverized coal, and a computer collects data of the particle size distribution data in the laser particle size tester;

e) And after the experiment is finished, the computer controls a second motor of the second booster pump to start, the second booster pump boosts the axial pressure reduction cavity, and meanwhile, the computer controls the second motors of the first booster pump and the third booster pump to rotate reversely to unload the pressure.