AU2020103791A4 - Complex resistance measurement system and method for nitrogen displacement of coal bed gas - Google Patents
Complex resistance measurement system and method for nitrogen displacement of coal bed gas Download PDFInfo
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- AU2020103791A4 AU2020103791A4 AU2020103791A AU2020103791A AU2020103791A4 AU 2020103791 A4 AU2020103791 A4 AU 2020103791A4 AU 2020103791 A AU2020103791 A AU 2020103791A AU 2020103791 A AU2020103791 A AU 2020103791A AU 2020103791 A4 AU2020103791 A4 AU 2020103791A4
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21C—MINING OR QUARRYING
- E21C45/00—Methods of hydraulic mining; Hydraulic monitors
- E21C45/02—Means for generating pulsating fluid jets
- E21C45/04—Means for generating pulsating fluid jets by use of highly pressurised liquid
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21C—MINING OR QUARRYING
- E21C41/00—Methods of underground or surface mining; Layouts therefor
- E21C41/16—Methods of underground mining; Layouts therefor
- E21C41/18—Methods of underground mining; Layouts therefor for brown or hard coal
Abstract
Complex resistance measurement system and method for nitrogen displacement of
coal bed gas, which comprises gas tank, nitrogen tank, pressure gauge, valve, pressure
regulating valve, flow meter, vacuum pump, holder, confining pressure pump, axial
pressure pump, resistance measuring instrument, computer, gas chromatograph, mixed
gas collection box and constant temperature water bath box; the confining pressure
pump is connected to the confining pressure interface, and the axial pressure pump is
connected to the axial pressure interface; the gas tank and the nitrogen tank are
respectively connected to the gas inlet of the holder through the ventilation pipe. The
mixed gas collection box is connected to the gas outlet of the holder through a pipe, the
gas chromatograph is provided on the pipe, which is connected to the computer in
communication; the complex resistance measuring instrument is connected to the left
and right electrode plates of the holder, which is connected to the computer in
communication; the system and method of the present invention test the change in the
complex resistance during the process of nitrogen displacement of gas in the coal, which
provides the application of the complex resistance method in coal bed logging
technology with strong experimental support.
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Description
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The invention belongs to the technical field of non-contact evaluation of hydraulic fracturing effect, and particularly relates to a complex resistance measurement system and method for nitrogen displacement of coal bed gas.
The coal mines in China are rich in coal bed gas (gas) resources. With the increase of mining depth of coal bed, the ground stress and gas pressure of the coal bed are increased gradually. In addition, the permeability of the coal bed is low and gas extraction is difficult, which makes coal and gas outburst disaster more and more serious. Therefore, improving the gas extraction rate is of great significance for preventing coal and gas accidents.
In the coal bed gas mining industry, injecting carbon dioxide or nitrogen into coal bed to promote the recovery of methane is one of the main methods to improve the recovery efficiency of coal bed gas at present, which is also the key research technology of coal bed gas development at home and abroad at present. The ability of adsorbing gas by coal is nitrogen > carbon dioxide > methane. Compared with carbon dioxide, nitrogen has a better displacement ability and environmental protection ability. In recent years, scholars at home and abroad have studied the theory of adsorbing nitrogen by coal, the action mechanism of injecting nitrogen to displace coal bed methane, the nitrogen smoldering pressure in coal bed methane well, hydraulic fracturing nitrogen foam injection in coal bed methane and the like, which indicates the technical feasibility of injecting nitrogen into coal bed gas wells to improve the recovery of the coal bed gas. At present, a plurality of coal mines in China adopt nitrogen displacement method in the coal bed methane mining industry, and a good effect is achieved.
In recent years, the study at home and abroad is based on the mechanism and technology o nitrogen displacement of coal bed gas. There are few studies on evaluating the displacement effect. In recent years, the complex resistance method has a lot of studies on measuring water saturation, predicting permeability and distinguishing oil-bearing water layer in the field of rock, which indicates that the complex resistance method has a good application prospect in coal bed logging technology. It is very important to select a suitable method to study and evaluate the process of displacing coal bed gas by nitrogen.
The invention aims to provide a complex resistance measurement system for nitrogen displacement of coal bed gas, which are convenient to use and good in using effect.
In order to solve the technical problems, the invention provides the following technical scheme that the complex resistance measurement system for nitrogen displacement of coal bed gas comprises gas tank, nitrogen tank, pressure gauge, valve, pressure regulating valve, flow meter, vacuum pump, holder, pressure-enclosing pump, shaft pressure pump, complex resistance measuring instrument, computer, gas chromatograph, mixed gas collecting box and constant temperature water bath box, wherein the holder is arranged in the constant temperature water bath box;
The holder comprises the cylinder body, wherein the coal sample cylinder is arranged in the cylinder body; confining pressure interface for applying confining pressure to the coal sample cylinder and an axial pressure interface for applying axial pressure to the coal sample cylinder are arranged on the cylinder body: ;
The coal sample cylinder is communicated with gas inlet and gas outlet; meanwhile, the two ends of the coal sample cylinder are respectively provided with left electrode plate and right electrode plate; The gas tank and the nitrogen tank are respectively connected with the gas inlet of the holder through air pipelines, and pressure gauge, pressure regulating valve, valve and flow meter are arranged on the air pipelines; The mixed gas collecting box is connected to the gas outlet of the holder through pipeline, flow meter and gas chromatograph are arranged on the pipeline, and signal output end of the gas chromatograph is in communication connection with a computer;
The two poles of the complex resistance measuring instrument are respectively connected with the left electrode plate and the right electrode plate of the holder through leads, and the signal output end of the complex resistance measuring instrument is in communication connection with a computer;
The confining pressure pump is communicated with the confining pressure interface of the holder;
And the shaft pressure pump is communicated with the shaft pressure interface of the holder.
The left and right nuts are respectively arranged at both ends of the cylinder body; the rubber sealing sleeve is arranged in the cylinder body; the mounting cover is connected outside the left nut through threads; the left pressure head is hermetically arranged in the mounting cover; the left mounting seat is arranged between the left pressure head and the left nut; the piston cylinder is connected outside the right nut through threads; the oil cylinder cover is fixed outside the piston cylinder through screws; the hollow piston is arranged in the piston cylinder; the hollow piston penetrates through the oil cylinder cover and is in sliding sealing fit with the oil cylinder cover; and the right mounting seat is arranged between the hollow piston and the right nut.
The left end and the right end of the rubber sealing sleeve are respectively sleeved on the left mounting seat and the right mounting seat; left plug, left electrode plate, coal sample cylinder, right electrode plate, right plug and right pressure head are sequentially arranged between the left pressure head and the hollow piston from left to right in the rubber sealing sleeve; the central vent hole is formed in the axial centers of the left pressure head, the left plug, the left electrode plate, the right electrode plate, the right plug and the right pressure head, wherein the gas inlet is arranged at the through hole of the left pressure head; the gas outlet is arranged at a through hole of the right pressure head; the left wiring slot is correspondingly arranged on the left pressure head and the left plug, and the right wiring slot is correspondingly arranged on the right plug and right pressure head. The left and right wiring grooves are respectively provided with left electrode plate and right electrode plate connected with the wire.
The confining pressure interface is arranged on the left nut, which is communicated with the confining pressure cavity formed by the left nut, the cylinder body, the right nut, the right mounting seat, the rubber sealing sleeve and the left mounting seat; and the shaft pressure interface is communicated with the shaft pressure cavity formed by the piston cylinder, the oil cylinder cover and the hollow piston.
The left mounting seat and the right mounting seat are of a wedge-shaped structure, and O-shaped sealing rings are respectively arranged on the contact surfaces of the left mounting seat and the left nut and the contact surfaces of the right mounting seat and the right nut.
The left plug and the right plug are insulating materials, the left electrode plate is fixedly arranged on the left plug, and the right electrode plate is fixedly arranged on the right plug.
The cylinder body and the coal sample cylinder are made of PPEK insulating materials; the left electrode plate and the right electrode plate are made of copper metal plates; and the coal sample cylinder is a cylinder body with the inner diameter of 5cm and the length of 10cm.
The complex resistance measurement system for nitrogen displacement of coal bed gas by using the system comprises the following steps in sequence:
(1) Connecting the experimental device, checking the air tightness of the device and confirming that the air tightness of an experimental system is good;
(2) Opening the vacuum pump, vacuuming the holder, filling helium gas after finishing, and measuring the volume of the holder and the volume of free space;
(3) Making the coal sample into a coal column with the length of 100mm and the diameter of 50mm, putting the coal column into coal sample cylinder of the holder, and carrying out vacuum degassing until the system pressure value is1OPa;
(4) Opening the constant-temperature water bath box to ensure that the
temperature in the constant-temperature water bath box is 30 DEG C until the
experiment is finished;
(5) The holder is connected with shaft pressure pump and confining pressure pump, the shaft pressure pump and the confining pressure pump are opened, and the shaft pressure and the confining pressure are set to simulate ground stress, and the setting ranges of the shaft pressure and the confining pressure are all 6-1OMpa;
(6) Opening the valve and fill the coal sample cylinder with gas. When the pressure gauge shows the preset gas pressure P1, where P1 is 1Mpa; leaving it for 12 24h, after the coal adsorbed gas is stable, close the valve to make the gas in the holder adequate adsorption to reach equilibrium;(7) Calculating the residual volume of the holder;
(8) Opening the control valve of the nitrogen tank, setting pressure through the pressure regulating valve, enabling nitrogen in the nitrogen tank to enter the holder to contact with the coal sample, displacing gas in the coal sample, enabling the displaced mixed gas to flow out of the gas chromatograph, uploading the contents of the gas and the nitrogen to the computer through data line after the gas chromatograph analyzes, and finally enabling the mixed gas to enter the mixed gas collecting box;
Observing the relationship between the complex resistance parameter obtained in the step (8) and the gas volume in the coal column obtained in the step (7).
In the step (7), the calculation method of the residual volume VR of the holder is as follows:
Firstly, detecting the true pair density P TRD of the coal sample;
Then the volume VC of the pure coal is calculated according to the formula (1), and the residual volume of the adsorption cavity, namely the volume VR of the gas adsorbed by the coal column, is calculated according to the formula (2);
Then calculating the gas volume VP absorbed by the coal column under normal pressure according to the formula (3) and the formula (4);
VC prao X m (1)
VR = VS-VC (2)
V PIVR (3) PO
P 1 = ¶/(Pv) + (P)(4)
In the formula, Vc is the volume of pure coal, the unit iscm 3 ,pTRD is the true-to density of the coal column, the unit is cm3/g, m is the mass of the coal column, the unit is g, VR is the volume of adsorbed gas of the coal column, the unit is cm3, Vs is the volume of a coal sample cylinder of a holder, the unit is cm3 , PO is the standard atmospheric pressure, the unit is Pa, Pi is the pressure in a cavity, the unit is Pa, PV is the axial pressure, the unit is Pa, and Pz is the confining pressure, the unit is Pa.
Through the technical scheme, the system disclosed by the invention has the beneficial effects that the displacement of the gas in the coal bed by the nitrogen is realized, the measurement of the influence of the nitrogen displacement on the complex resistance of the coal body is researched in the displacement process, and a powerful experimental support is provided for the application of the complex resistance method in the coal bed logging technology.
The method provided by the invention has the advantages that the steps are compact, the complex resistance of the coal body is measured in the process of testing the displacement of the gas in the coal body by the nitrogen gas, and a powerful experimental support is provided for the application of the complex resistance method in the coal bed logging technology.
Figure 1 is the structure schematic view of the present invention;
Figure 2 is the structure schematic view of the holder.
As shown in FIGS. 1 and 2, the complex resistance measurement system for nitrogen displacement of coal bed gas comprises gas tank 12, nitrogen tank 13, pressure gauge 14, valve 15, pressure regulating valve 16, flow meter 17, vacuum pump 18, holder 19, pressure-enclosing pump 21, shaft pressure pump 22, complex resistance measuring instrument 23, computer 24, gas chromatograph 25, mixed gas collecting box 26 and constant temperature water bath box 20, wherein the holder 19 is arranged in the constant temperature water bath box 20, so that the coal sample in the holder 19 is kept at a constant temperature, and the stability and reliability of the measuring process are ensured.
In order to ensure the use effect of the constant temperature water bath box 20, the constant temperature water bath box control part 27 is connected to the constant
temperature water bath box, and the constant temperature water bath box control part
27 comprises the temperature sensor, the single chip and the electric heating layer arranged on the side wall of the constant temperature water bath box.
The electric heating layer comprises electric heating wires, the inter layer is arranged on the side wall of the constant-temperature water bath box, and the electric heating wires are arranged in the inner layer.
The temperature sensor is arranged in the constant-temperature water bath box
, meanwhile, the signal output end of the temperature sensor is connected with the signal input end of the single chip, the signal output end of the single chip is connected with a relay driving circuit, the relay driving circuit is mature in the prior art, and the output signal of the single chip controls whether the power supply circuit of the electric heating wire is switched on or not through the relay driving circuit so as to control the work of the electric heating wire.
Wherein the complex resistance measuring instrument 23 is the IM3533-O1LCR complex resistance measuring instrument 23, and the gas chromatograph 25 is the GC-4000A gas chromatograph 25.
The holder 19 comprises cylinder 8, coal sample cylinder 7 is arranged in the cylinder 8, confining pressure interface 3 for exerting confining pressure on the coal sample cylinder 7 and axial pressure interface 9 for exerting axial pressure on the coal sample cylinder 7 are arranged on the cylinder 8. The pressure-limiting pump 21 is in communication with the pressure-limiting interface 3 of the holder 19, and the shaft pressure pump 22 is in communication with the shaft pressure interface 9 of the holder 19.
The coal sample cylinder 7 is communicated with the gas inlet 1 and the gas outlet 10, and the two ends of the coal sample cylinder 7 are respectively provided with the left electrode plate 5 and the right electrode plate. The cylinder body 8 and the coal sample cylinder 7 are made of PPEK insulating material, the left electrode plate 5 and the right electrode plate are made of copper metal plates, and the coal sample cylinder 7 is a cylinder body with the inner diameter of 5cm and the length of cm.
The vacuum pump is also connected with the gas inlet 1 of the holder, and the coal sample cylinder 7 of the holder can be vacuumed through the vacuum pump, so that the use is convenient.
The gas tank 12 and the nitrogen tank 13 are respectively connected with the gas inlet 1 of the holder 19 through a vent pipe, and the vent pipe is provided with the pressure gauge 14, the pressure regulating valve 16, the valve 15 and the flow meter 17.
The control valve 15 is arranged on each of the gas tank 12 and the nitrogen tank 13, and when in use, the gas tank 12 or the nitrogen tank 13 is opened according to requirements, so that the gas tank 12 or the nitrogen tank 13 can introduce gas or nitrogen into the holder 19 through the vent pipe, and the gas or nitrogen enters the coal sample of the coal sample cylinder 7 in the holder 19 and is adsorbed by the coal sample.
Wherein the pressure gauge 14 can read the pressure of the gas or nitrogen which is introduced into the holder 19 in real time, the pressure of the gas or nitrogen which is introduced into the holder 19 can be regulated by the pressure regulating valve 16, and the valve 15 can control whether the vent pipe is communicated or not.
The mixed gas collecting tank 26 is connected to the gas outlet 10 of the holder 19 through a pipeline, the pipeline is provided with the flow meter 17 and the gas chromatograph 25, and the signal output end of the gas chromatograph 25 is in communication connection with the computer 24.
The gas coming out of the holder 19 passes through the flow meter 17 and the gas chromatograph 25 in this order, the flow rate of the gas which can be read out by the flow meter 17, and the amounts of the nitrogen and the gas can be analyzed out by the cooperation of the gas chromatograph 25 and the computer 24, respectively. The content of the gas is analyzed by a meteorological chromatograph to be a mature prior art. The gas passing through the gas chromatograph 25 finally enters the mixed gas collecting tank 26 to be collected.
The two poles of the complex resistance measuring instrument 23 are respectively connected with the left electrode plate and the right electrode plate of the holder 19 through the lead wires 4, and the signal output end of the complex resistance measuring instrument 23 is in communication connection with the computer 24.
The structure of the holder 19 is described in detail below for the use effect:
The two ends of the cylinder body 8 are respectively provided with left and right nut;
The rubber sealing sleeve 6 is arranged in the cylinder 8; the mounting cover is connected outside the left nut through threads; the left pressure head is hermetically arranged in the mounting cover; the left mounting seat is arranged between the left pressure head and the left nut; the piston cylinder is connected outside the right nut through threads; the oil cylinder cover is fixed outside the piston cylinder through screws; the hollow piston is arranged in the piston cylinder; the hollow piston penetrates through the oil cylinder cover and is in sliding sealing fit with the oil cylinder cover; and the right mounting seat is arranged between the hollow piston and the right nut.
The left end and the right end of the rubber sealing sleeve 6 are respectively sleeved on the left mounting seat and the right mounting seat, the left mounting seat and the right mounting seat are in a wedge-shaped structure, and the contact surface of the left mounting seat and the left nut and the contact surface of the right mounting seat and the right nut are respectively provided with O-shaped sealing ring 2.
In the rubber sealing sleeve 6, left plug 11, left electrode plate 5, coal sample cylinder 7, right electrode plate, right plug and right pressure head are sequentially arranged between the left pressure head and the hollow piston from left to right; a central vent hole is formed in the axial centers of the left pressure head, the left plug 11, the left electrode plate 5, the right electrode plate, the right plug and the right pressure head; a gas inlet 1 is arranged at a through hole of the left pressure head; a gas outlet 10 is arranged at a through hole of the right pressure head; The left pressure head and the left plug 11 are correspondingly provided with a left wiring groove, the right plug and the right pressure head are correspondingly provided with a right wiring groove, and the left and right wiring grooves are respectively provided with a left electrode plate 5 and Right electrode plate.
The confining pressure interface 3 is arranged on the left screw cap, the confining pressure interface 3 is communicated with the left screw cap, the cylinder body 8, the right screw cap, the right mounting seat, the rubber sealing sleeve 6 and the left mounting seat to form a confining pressure cavity, and the shaft pressure interface 9 is communicated with the piston cylinder, the oil cylinder cover and the hollow piston to form a shaft pressure cavity.
Wherein the left plug 11 and the right plug are insulating materials; the left electrode plate 5 is fixedly arranged on the left plug 11; and the right electrode plate is fixedly arranged on the right plug.
The system disclosed by the invention realizes the displacement of the gas in the coal bed by the nitrogen, realizes the measurement of the influence of the nitrogen displacement on the complex resistance of the coal body 20, and provides a powerful experimental support for the application of the complex resistance method in the coal bed logging technology.
The invention also discloses a complex resistance measurement system for nitrogen displacement of coal bed gas by using the system, which sequentially comprises the following steps:
(1) Connecting experimental device to check the air tightness of the device, and confirming that the experimental system has good air tightness;
(2) Opening the vacuum pump, vacuuming the holder, filling helium gas after finishing, and measuring the volume of the holder and the volume of free space.
(3) Making the coal sample into a coal column with the length of 100mm and the diameter of 50mm, putting the coal column into a coal sample cylinder of the holder, and performing vacuum degassing until the vacuum gauge shows that the pressure value of the pressure system is 1OPa and stopping.
(4) Opening the constant-temperature water bath box to ensure that the temperature in the constant-temperature water bath box is 30 DEG C until the experiment is finished.
(5) The holder is connected with the axial pressure pump and the confining pressure pump, the axial pressure pump and the confining pressure pump are opened, and the axial pressure and the confining pressure are set. The axial pressure and the confining pressure value are both set to simulate ground stress, the change range is 6Mpa-1Mpa, the change gradient is 2Mpa, the axial pressure is unchanged, the confining pressure is changed, and nine pressure changes are carried out on coal with the same metamorphic degree in the experiment process: the axial pressure is 6Mpa, the confining pressure is 6Mpa, 8Mpa and 1OMpa; the axial pressure is 8Mpa, the confining pressure is 6Mpa, 8Mpa and 1OMpa; and the axial pressure is 1OMpa, the confining pressure is 6Mpa, 8Mpa and 1OMpa.
(6) Opening the valve, filling gas into the coal sample cylinder, when the pressure gauge displays the preset gas pressure is Pi, wherein Pi is IMpa, placing for 12-24h, and closing the valve after the coal adsorbs the gas stably, so that the gas is fully adsorbed in the holder to reach balance.
(7) Calculating the residual volume VR of the holder, wherein the testing method comprises the following steps:
Firstly, measuring the true contrast density P TRD of a coal sample;
Then the volume Vc of the pure coal is calculated according to the formula (1), and the residual volume of the adsorption cavity, namely the volume VR of the gas adsorbed by the coal column, is calculated according to the formula (2);
Then calculating the gas volume VP absorbed by the coal column under normal pressure according to the formula (3) and the formula (4);
VC -PTRD Xmi (1) V? = P xCm (2)
VP= -- (3) PG
P,- (pV) 2 + (p) 2 (4)
In the formula, Vc is the volume of pure coal, the unit iscm 3 ,PTRD is the true-to density of the coal column, the unit is cm 3/g, m is the mass of the coal column, the unit is g, VR is the volume of adsorbed gas of the coal column, the unit is cm 3, Vs is the volume of a coal sample cylinder of a holder, the unit is cm3 , Po is the standard atmospheric pressure, the unit is Pa, Pi is the pressure in a cavity, the unit is Pa, Pv is the axial pressure, the unit is Pa, and Pz is the confining pressure, the unit is Pa.
(8) Opening the valve of the nitrogen tank, setting the pressure through the pressure regulating valve, the nitrogen in the nitrogen tank enters the holder, the nitrogen entering the holder displaces the gas in the coal sample, and the displaced mixed gas flows out to the gas chromatograph after being analyzed by gas chromatograph, the content of gas and nitrogen is uploaded to the computer through the data line, and the mixed gas finally enters the mixed gas collection box; on the other hand, during the displacement process, the complex resistance measuring instrument is turned on to measure the coal pillar Complex resistance parameters when adsorbing different gas contents.
(9) Observing the relationship between the complex resistance parameter obtained in the step (8) and the gas volume in the coal column obtained in the step (7).
The method of the invention has compact steps and provides powerful experimental support for the application of complex resistivity method in coal bed logging technology by testing the change of coal body complex resistance in the process of nitrogen displacement in coal body.
Claims (9)
1. Complex resistance measurement system for nitrogen displacement of coal bed gas, which is characterized by comprising gas tank, nitrogen tank, pressure gauge, valve, pressure regulating valve, flow meter, vacuum pump, holder, pressure enclosing pump, shaft pressure pump, complex resistance measuring instrument, computer, gas chromatograph, mixed gas collecting box and constant temperature water bath box, wherein the holder is arranged in the constant temperature water bath box;
The holder comprises the cylinder body, wherein the coal sample cylinder is arranged in the cylinder body; confining pressure interface for applying confining pressure to the coal sample cylinder and axial pressure interface for applying axial pressure to the coal sample cylinder are arranged on the cylinder body;
The coal sample cylinder is communicated with gas inlet and gas outlet; meanwhile, the two ends of the coal sample cylinder are respectively provided with left electrode plate and right electrode plate;
The gas tank and the nitrogen tank are respectively connected with the gas inlet of the holder through air pipelines, and pressure gauge, pressure regulating valve, valve and flow meter are arranged on the air pipelines;
The vacuum pump is also connected with the gas inlet of the holder;
The mixed gas collecting box is connected to the gas outlet of the holder through pipeline, flow meter and gas chromatograph are arranged on the pipeline, and signal output end of the gas chromatograph is in communication connection with a computer;
The two poles of the complex resistance measuring instrument are respectively connected with the left electrode plate and the right electrode plate of the holder through leads, and the signal output end of the complex resistance measuring instrument is in communication connection with a computer;
The confining pressure pump is communicated with the confining pressure interface of the holder;
And the shaft pressure pump is communicated with the shaft pressure interface of the holder.
2. The complex resistance measurement system for nitrogen displacement of coal bed gas according to claim 1, which is characterized in that the left and right nuts are respectively arranged at both ends of the cylinder body; the rubber sealing sleeve is arranged in the cylinder body; the mounting cover is connected outside the left nut through threads; the left pressure head is hermetically arranged in the mounting cover; the left mounting seat is arranged between the left pressure head and the left nut; the piston cylinder is connected outside the right nut through threads; the oil cylinder cover is fixed outside the piston cylinder through screws; the hollow piston is arranged in the piston cylinder; the hollow piston penetrates through the oil cylinder cover and is in sliding sealing fit with the oil cylinder cover; and the right mounting seat is arranged between the hollow piston and the right nut.
3. The complex resistance measurement system for nitrogen displacement of coal bed gas according to claim 2,, which is characterized in that the left and right ends of the rubber sealing sleeve are respectively sleeved on the left and right mounting seats, left plug, left electrode plate, coal sample tube, right electrode plate, right plug and right pressure head are arranged in order from left to right between the left pressure head and the hollow piston in the rubber sealing sleeve. A central vent is provided in the axial center of the head, the left electrode plate, the right electrode plate, the right plug and the right indenter, wherein the gas inlet is arranged at the through hole of the left indenter, and the gas outlet is arranged at the through hole of the right indenter; the left pressure head and the left plug are correspondingly provided with left wiring groove, right plug and right indenter, and the left and right wiring grooves are respectively provided with left and right electrode plates connected with wires.
4. The complex resistance measurement system for nitrogen displacement of coal bed gas according to claim 3, which is characterized in that the confining pressure interface is arranged on the left nut, the confining pressure interface is communicated with the confining pressure cavity enclosed by the left nut, the cylinder body, the right nut, the right mounting seat, the rubber sealing sleeve and the left mounting seat, and the shaft pressure interface is communicated with the shaft pressure cavity enclosed by the piston cylinder, the oil cylinder cover and the hollow piston.
5. The complex resistance measurement system for nitrogen displacement of coal bed gas according to claim 4, which is characterized in that the left mounting seat and the right mounting seat are of a wedge-shaped structure, and O-shaped sealing rings are respectively arranged on the contact surface of the left mounting seat and the left nut and the contact surface of the right mounting seat and the right nut.
6. The complex resistance measurement system for nitrogen displacement of coal bed gas according to claim 5, which is characterized in that the left plug and the right plug are insulating materials, the left electrode plate is fixedly arranged on the left plug, and the right electrode plate is fixedly arranged on the right plug.
7. The complex resistance measurement system for nitrogen displacement of coal bed gas according to any one of claims 1-6,, which is characterized in that the cylinder body and the coal sample cylinder are made of PPEK insulating materials; the left electrode plate and the right electrode plate are copper metal plates; and the coal sample cylinder is a cylinder body with the inner diameter of 5cm and the length of cm.
8. The complex resistance measurement system for nitrogen displacement of coal bed gas according to claim 1, which is characterized by comprising the following steps in sequence:
(1) Connecting experimental device, checking the air tightness of the device and confirming that the air tightness of the experimental system is good;
(2) Opening the vacuum pump, vacuuming the holder, filling helium gas after finishing, and measuring the volume of the holder and the volume of free space;
(3) Making the coal sample into a coal column with the length of 100mm and the diameter of 50mm, putting the coal column into coal sample cylinder of the holder, and carrying out vacuum degassing until the system pressure value is1OPa;
(4) Opening the constant-temperature water bath box to ensure that the temperature in the constant-temperature water bath box is 30 DEG C until the experiment is finished;
(5) The holder is connected with the shaft pressure pump and the confining pressure pump, the shaft pressure pump and the confining pressure pump are opened, and the shaft pressure and the confining pressure are set to simulate ground stress, and the setting ranges of the shaft pressure and the confining pressure are all 6-1OMpa;
(6) Opening the valve and fill the coal sample cylinder with gas. When the pressure gauge shows the preset gas pressure P1, where P1 is 1Mpa; leaving it for 12 24h, after the coal adsorbed gas is stable, closing the valve to make the gas in the holder adequate adsorption to reach equilibrium;
(7) Calculating the residual volume of the holder;
(8) Opening the control valve of the nitrogen tank, setting pressure through the pressure regulating valve, enabling nitrogen in the nitrogen tank to enter the holder to contact with the coal sample, displacing gas in the coal sample, enabling the displaced mixed gas to flow out of the gas chromatograph, uploading the contents of the gas and the nitrogen to the computer through data line after the gas chromatograph analyzes, and finally enabling the mixed gas to enter the mixed gas collecting box;
(9) Observing the relationship between the complex resistance parameter obtained in the step (8) and the gas volume in the coal column obtained in the step (7).
9. The complex resistance measurement system for nitrogen displacement of coal bed gas according to claim 8, which is characterized in that the calculation method of the residual volume VR of the holder in step (7) is as follows:
Firstly, detecting the true pair density PTRD of the coal sample;
Secondly, calculating the volume Vc of the pure coal according to the formula (1), and calculating the remaining volume of the holder, namely the volume VR of the gas adsorbed by the coal column, according to the formula (2);
Then calculating the gas volume VP absorbed by the coal column under normal pressure according to the formula (3) and the formula (4);
V =PTDX M (1)
VI? = V7- V (2)
VP P1VR(3) P0 P, A(p~y +(pZ) 2 (4)
In the formula, Vc is the volume of pure coal, the unit is cm 3, R is the true to-density of the coal column, the unit is cm 3/g, m is the mass of the coal column, the unit is g, VR is the volume of adsorbed gas of the coal column, the unit is cm3, VS is the volume of a coal sample cylinder of a holder, the unit is cm3 , Po is the standard atmospheric pressure, the unit is Pa, Pi is the pressure in a cavity, the unit is Pa, Pv is the axial pressure, the unit is Pa, and Pz is the confining pressure, the unit is Pa.
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Figure 1
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Figure 2
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113358846A (en) * | 2021-06-11 | 2021-09-07 | 中煤科工集团重庆研究院有限公司 | Gas-supplementing coal and gas outburst dynamic effect simulation experiment device and method |
| CN113959896A (en) * | 2021-10-22 | 2022-01-21 | 中国石油大学(北京) | Method and device for simulating carbon dioxide to replace methane in coal bed |
| CN114660263A (en) * | 2022-03-07 | 2022-06-24 | 中国地质大学（北京） | Shale gas content measuring device |
-
2020
- 2020-11-30 AU AU2020103791A patent/AU2020103791A4/en not_active Ceased
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113358846A (en) * | 2021-06-11 | 2021-09-07 | 中煤科工集团重庆研究院有限公司 | Gas-supplementing coal and gas outburst dynamic effect simulation experiment device and method |
| CN113358846B (en) * | 2021-06-11 | 2023-03-28 | 中煤科工集团重庆研究院有限公司 | Gas-supplementing coal and gas outburst dynamic effect simulation experiment device and method |
| CN113959896A (en) * | 2021-10-22 | 2022-01-21 | 中国石油大学(北京) | Method and device for simulating carbon dioxide to replace methane in coal bed |
| CN113959896B (en) * | 2021-10-22 | 2023-07-25 | 中国石油大学(北京) | Method and device for simulating carbon dioxide to replace methane in coal bed |
| CN114660263A (en) * | 2022-03-07 | 2022-06-24 | 中国地质大学（北京） | Shale gas content measuring device |
| CN114660263B (en) * | 2022-03-07 | 2022-11-01 | 中国地质大学（北京） | Shale gas content measuring device |
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