CN108303509B - Device and method for correcting free amount calculation of coal bed gas and measuring residual adsorption amount - Google Patents
Device and method for correcting free amount calculation of coal bed gas and measuring residual adsorption amount Download PDFInfo
- Publication number
- CN108303509B CN108303509B CN201810012086.8A CN201810012086A CN108303509B CN 108303509 B CN108303509 B CN 108303509B CN 201810012086 A CN201810012086 A CN 201810012086A CN 108303509 B CN108303509 B CN 108303509B
- Authority
- CN
- China
- Prior art keywords
- gas
- coal sample
- tank body
- adsorption
- coal
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- 239000003245 coal Substances 0.000 title claims abstract description 184
- 238000001179 sorption measurement Methods 0.000 title claims abstract description 124
- 238000000034 method Methods 0.000 title claims abstract description 29
- 238000004364 calculation method Methods 0.000 title claims abstract description 19
- 230000001105 regulatory effect Effects 0.000 claims abstract description 21
- 238000004458 analytical method Methods 0.000 claims abstract description 5
- 238000007789 sealing Methods 0.000 claims description 29
- 239000011148 porous material Substances 0.000 claims description 9
- 238000009792 diffusion process Methods 0.000 claims description 8
- 230000006835 compression Effects 0.000 claims description 6
- 238000007906 compression Methods 0.000 claims description 6
- 238000001035 drying Methods 0.000 claims description 5
- 238000007872 degassing Methods 0.000 claims description 4
- 238000006073 displacement reaction Methods 0.000 claims description 3
- 230000003287 optical effect Effects 0.000 claims description 3
- 238000005498 polishing Methods 0.000 claims description 3
- 238000001291 vacuum drying Methods 0.000 claims description 3
- 238000012935 Averaging Methods 0.000 claims description 2
- 244000137852 Petrea volubilis Species 0.000 claims description 2
- 238000012937 correction Methods 0.000 claims description 2
- 238000005259 measurement Methods 0.000 claims description 2
- 238000000465 moulding Methods 0.000 claims description 2
- 239000000126 substance Substances 0.000 claims 3
- 239000007789 gas Substances 0.000 description 209
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 12
- 238000002474 experimental method Methods 0.000 description 5
- 239000003345 natural gas Substances 0.000 description 5
- 230000008569 process Effects 0.000 description 5
- 230000009286 beneficial effect Effects 0.000 description 3
- 238000011161 development Methods 0.000 description 3
- 238000010494 dissociation reaction Methods 0.000 description 3
- 230000005593 dissociations Effects 0.000 description 3
- 238000011156 evaluation Methods 0.000 description 3
- 239000011435 rock Substances 0.000 description 3
- 230000001808 coupling effect Effects 0.000 description 2
- 230000001133 acceleration Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 238000003795 desorption Methods 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 239000000295 fuel oil Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000013507 mapping Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 238000005065 mining Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/22—Fuels; Explosives
- G01N33/222—Solid fuels, e.g. coal
Landscapes
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Food Science & Technology (AREA)
- Medicinal Chemistry (AREA)
- Physics & Mathematics (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Sampling And Sample Adjustment (AREA)
Abstract
The invention relates to a device and a method for correcting free amount calculation of coal bed gas and measuring residual adsorption amount, belonging to the technical field of coal mine safety, wherein the device comprises an adsorption tank body, a gas pressure reducing valve, a Roots vacuum pump, a gas pressure regulating valve and a gas storage tank; the adsorption tank body is used for storing the coal sample, the adsorption tank body is arranged in a constant-temperature air bath environment, and a rotary platform is arranged below the adsorption tank body; an X-ray source and a ray detector which are opposite to the adsorption tank body are fixedly arranged in the constant-temperature air bath, the ray detector is connected to a data acquisition and analysis system, a gas storage tank is connected to a gas pressure regulating valve, the other end of the gas pressure regulating valve is connected to a first port of a three-way valve, and a second port of the three-way valve is connected to a gas source through a gas needle valve I and a gas pressure reducing valve; and a third port of the three-way valve is connected to the roots vacuum pump through a gas needle valve II. The invention realizes the accurate determination of the porosity and the free gas content of the coal sample under different gas pressures and different loading conditions.
Description
Technical Field
The invention belongs to the technical field of coal mine safety, and relates to a device and a method for correcting free amount calculation of coal bed gas and measuring residual adsorption amount.
Background
Coal mine gas (also called coal bed gas) is unconventional natural gas which exists in a coal bed and surrounding rocks thereof in an adsorbed or free state and contains methane as a main component. China has rich coal bed gas resources, and can be known according to a new round of resource evaluation: the amount of shallow coal bed gas resources of 2000 m in China is about 36.81 billion cubic meters, which is equivalent to 490 billion standard coal and is third in the world. With the acceleration of the urbanization process of China and the improvement of the environmental protection requirement in recent years, natural gas is used as a clean and efficient energy source and is widely used for urban gas and industrial fuels such as substituted coal, fuel oil and the like. During the period from 2005 to 2015, the natural gas production capacity in China increases from 493 billion cubic meters to 1350 billion cubic meters, the consumption capacity increases from 468 billion cubic meters to 1931 billion cubic meters, and the annual composite growth rate in ten years is 10.6% and 15.2%, respectively. Therefore, the gap of natural gas consumption in China is continuously increased, the strength of coal bed gas exploration and development in coal mine areas is increased, and the situation of shortage of natural gas in China is relieved. The gas is mainly in the form of adsorption and dissociation in the coal bed and exists in the pore and fissure systems of the coal. The porosity of the medium-low rank coal is generally far greater than that of the high-rank coal, the content of macropores and mesopores which are beneficial to existence of free gas and circulation of coal bed gas is high, the content of the macropores and mesopores can reach more than 40%, the high-rank coal is dominated by pores with strong adsorption capacity such as micropores and micropores, and the development characteristics of the pores of the high-rank coal are different, so that the composition of gas content is different. The actual coal bed is in a certain gas pressure field, stress field and temperature field, so the pores of the coal are influenced by the coupling effect of the gas pressure, the stress and the temperature. At present, the block density of coal is generally measured by a sealing method or a volume method listed in a coal and rock physical and mechanical property measuring method in China, and the true density of the coal is measured by a pycnometer method or a gas expansion method true density analyzer, so that the porosity of the coal is calculated. The method can accurately determine the porosity of the coal sample under the condition that the coal sample does not contain gas, but strong adsorption exists between the coal and the gas, and different gas pressures can cause different deformations of the coal sample. The existing practice shows that: even under the condition of lower gas pressure, the relative change of the porosity of the coal caused by gas adsorption deformation can reach 17.98 percent at most. Therefore, the mapping rule of the gas pressure, the ground stress temperature and the coal porosity is taken into consideration, and on the basis, the calculation method of the coal bed gas free quantity is corrected, so that accurate basis can be provided for the evaluation of the coal bed gas resources of the reservoir. Meanwhile, as coal belongs to a special porous medium and has a complex pore structure, the adsorption of gas in the coal body is not ideal physical adsorption. The research results of a plurality of scholars show that: the coal adsorption capacity curve and the diffusion capacity curve under different gas equilibrium pressures do not coincide, namely: the isothermal desorption curve and the isothermal adsorption curve of the same coal sample to the gas have a residual adsorption capacity under a deficient pressure.
Disclosure of Invention
In view of the above, the present invention aims to provide a device and a method for correcting coal bed gas dissociation amount calculation and measuring residual adsorption amount, so as to solve the problem that the influence of gas pressure, ground stress and temperature coupling effect on the coal porosity cannot be considered in the coal bed gas dissociation amount calculation process, and provide an accurate scientific basis for the development planning scheme of coal bed gas in a coal mining area and the evaluation of coal bed gas resources in a reservoir.
In order to achieve the purpose, the invention provides the following technical scheme:
the device comprises an adsorption tank body, a gas pressure reducing valve, a Roots vacuum pump, a gas pressure regulating valve and a gas storage tank;
the adsorption tank body is used for storing a coal sample, an upper sealing stop block is arranged at the upper end of the adsorption tank body and connected to a press machine, the lower end of the adsorption tank body is connected to a bottom tray of the adsorption tank body through a connecting flange, and a gas circulation interface is arranged on the bottom tray of the adsorption tank body;
one end of the gas storage tank is connected to an adsorption tank body, the adsorption tank body is arranged in a constant-temperature air bath environment, and a rotary platform is arranged below the adsorption tank body;
an X-ray source and a ray detector which are opposite to the adsorption tank body are fixedly arranged in the constant-temperature air bath, the ray detector is connected to a data acquisition and analysis system, and a gas mass flow meter and a gas pressure sensor II are arranged on a pipeline connecting the adsorption tank body and the gas storage tank;
the other end of the gas storage tank is connected to one end of a gas pressure regulating valve, the other end of the gas pressure regulating valve is connected to a first port of a three-way valve, and a second port of the three-way valve is connected to a gas source through a gas needle valve I and a gas pressure reducing valve;
and a third port of the three-way valve is connected to the roots vacuum pump through a gas needle valve II.
Further, a gas pressure sensor I is arranged between the front end and the rear end of the gas storage tank, a vacuum thermocouple meter is further arranged on the Roots vacuum pump, and a gas outlet valve is further arranged at one end, connected with the adsorption tank body, of the gas storage tank.
Further, be provided with the recess on the flange, the adsorption tank body upper end still is provided with the sealing washer.
Further, the rotary platform is disposed on a multi-axis mechanical movement device disposed on the optical platform.
The method for correcting the calculation of the free amount of the coal bed gas and measuring the residual adsorption amount comprises the following steps of:
s1: preparing and molding the drilled coal sample, and then polishing the surface of the coal sample by using sand paper to flatten the surface of the coal sample;
s2: placing the prepared coal sample into a vacuum drying oven for drying treatment, and then measuring the size of the coal sample;
s3: calibrating the volume of the gas storage tank and the pipeline connected with the adsorption tank body, and recording the volume of the gas storage tank as VcThe volume of the pipeline connected between the gas storage tank and the adsorption tank body is Vg；
S3: putting a coal sample into an adsorption tank body, sealing the adsorption tank body, starting a press machine to enable an upper sealing stop block to generate displacement and to be in contact with the upper end face of the coal sample, then closing the press machine to enable the upper sealing stop block to stop moving, placing a felt between the upper sealing stop block and the upper end face of the coal sample, and recording the volume of the felt as VmRecording the volume of the adsorption tank body at the moment as Vx0；
S4: after the adsorption tank body is sealed, opening a gas needle valve II, closing a gas needle valve I, and degassing the whole tank body and a pipeline through a vacuum pump;
s5: when the vacuum thermocouple meter on the vacuum pump displays that the set threshold value is reached, the vacuum pump is closed, and the coal sample in the adsorption tank body is stopped from being degassed;
s6: adjusting a gas pressure regulating valve, enabling the pressure value of an outlet of the gas pressure regulating valve to reach a set threshold value, opening a gas needle valve I and a gas pressure reducing valve, enabling high-pressure gas to enter a gas storage tank through a pipeline, and recording the pressure value P when the numerical value of a gas pressure sensor I on the gas storage tank reaches the set threshold value1Then, opening a gas mass flowmeter and a gas outlet valve on a gas storage tank to enable high-pressure gas to enter the adsorption pipe body through a gas pipeline, and opening an air bath;
s7: the press is opened again toThe upper sealing stop block moves to apply axial stress to the coal sample, after the axial stress reaches a specified value, the moving distance delta L of the upper sealing stop block is recorded, meanwhile, the coal sample fully absorbs high-pressure gas under a loaded condition, and the volume V of the adsorption tank body at the moment is recordedxP；
S8: after the gas mass flowmeter is stable for a specified time interval, and the readings of the gas pressure sensor I and the gas pressure sensor II are the same, at the moment, the coal sample is considered to be adsorbed with gas balance, and the accumulated quantity Q of the gas mass flowmeter at the moment is recorded0And gas pressure sensor reading P2；
S9: starting the rotary platform, the X-ray source and the ray detector to scan the porosities of different layers of the coal sample, and averaging the porosity numerical values of different layers to obtain the adsorption equilibrium pressure P2And calculating the content of free gas in the coal sample, the molar quantity of the adsorbed gas of the coal sample and the content of the adsorbed gas of the coal sample according to the average porosity phi.
Further, it also comprises
Step S10: removing a pipeline connected between an air inlet valve of the air storage tank and a gas pressure regulating valve, enabling a coal sample in the adsorption tank to disperse gas under normal pressure, recording the gas diffusion amount under different dispersion time through a gas mass flowmeter until the reading of the gas mass flowmeter is displayed as 0ml/min, and recording the accumulated amount Q of the gas mass flowmeterf；
S11: step S9 is executed to obtain the porosity phi after the coal sample gas emission is finishedmAnd calculating the content of the free gas of the coal sample after the gas is diffused, the amount of the free gas after the gas is diffused and the residual adsorption amount.
Further, it also comprises
S12: and repeating the steps S4-S9 to obtain the free gas content and the adsorbed gas content of the coal sample under different adsorbed gas balance pressures and different axial loading conditions.
Further, the drying treatment time in step S2 was 24 hours or more, and the set threshold value reached as indicated by the vacuum thermocouple in step S5 was 4X 10-1Pa, step S8 specifies a time interval of 12 h.
Further, in step S9, the free gas content in the coal sample, the molar quantity of the adsorbed gas in the coal sample, and the adsorbed gas content in the coal sample are respectively:
wherein, WyP2At equilibrium pressure P for high-pressure gas2Free gas content, T, in the coal sample0、P0Respectively, absolute temperature and absolute pressure in a standard state, T is the absolute temperature in the air bath, VkPore volume per unit mass of coal, Vk＝[Φ×π×R2×L×(1-ΔL)]M is the mass of the coal sample, L is the height of the coal sample, R is the radius of the coal sample, Z2At equilibrium pressure P for high-pressure gas2A compression factor of time;
wherein n is1To balance the pressure P for the gas2When the coal sample is adsorbing the molar amount of gas, Z1Is a high-pressure gas with a pressure of P1The compression factor of the gas;
wherein WxP2The adsorbed gas content of the coal sample.
Further, the residual adsorption amount of the free gas in the coal sample after the gas emission in step S11 is:
WxP2c＝Q0-Qf-WyP2m×M
wherein, WyP2mThe content of free gas in the coal sample after the gas emission is finished.
The invention has the beneficial effects that:
(1) the method for correcting the calculation of the free amount of the gas in the coal bed and measuring the residual adsorption amount can realize the accurate measurement of the porosity and the free gas content of the coal sample under different gas pressures and different loading conditions, and can provide technical support for researching the physical characteristics of the gas-containing coal;
(2) according to the method for correcting the calculation of the free amount of the coal bed gas and measuring the residual adsorption amount, the porosity, the free gas content and the adsorbed gas content of a coal sample test piece under different gas pressures and different loading conditions can be accurately measured, the obtained experimental data can be further subjected to numerical analysis, the correlation between the axial stress and the adsorption balance gas pressure and the porosity and the adsorption amount can be obtained through fitting, not only can the equation of the free gas content be corrected, but also the porosity under different gas pressure conditions can be corrected, the correction of the calculation of the coal bed gas content can be finally realized, and a scientific basis is provided for accurately evaluating the coal bed gas resources of a reservoir and the outburst danger of coal and gas;
(3) according to the method for correcting the calculation of the free amount of the coal bed gas and measuring the residual adsorption amount, after the adsorption amount, the porosity and the free gas amount of the coal sample under the corresponding loaded condition are measured, the residual adsorption amount of the coal sample under the conditions of different stresses and gas balance pressure can be accurately measured by opening the gas valve, and a reliable technical support is provided for researching the coal bed gas diffusion mechanism.
Drawings
In order to make the object, technical scheme and beneficial effect of the invention more clear, the invention provides the following drawings for explanation:
FIG. 1 is a schematic view of an adsorption tank of the present invention;
FIG. 2 is a schematic view of the structure of the apparatus of the present invention.
Detailed Description
Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
As shown in fig. 1-2, the device for correcting the calculation of the free amount of coal bed gas and measuring the residual adsorption amount comprises an adsorption tank 5, a gas pressure reducing valve 15, a roots vacuum pump 20, a gas pressure regulating valve 22 and a gas storage tank 23;
the adsorption tank body 5 is used for storing a coal sample 1, an upper sealing stop block 2 is arranged at the upper end of the adsorption tank body 5, the upper sealing stop block 2 is connected to a press machine, 28 in the drawing, the lower end of the upper sealing stop block is connected to an adsorption tank body bottom tray 9 through a connecting flange 10, a gas circulation interface 8 is arranged on the adsorption tank body bottom tray 9, a groove 7 is further formed in the contact surface of the adsorption tank body bottom tray 9 and the adsorption tank body 5, the adsorption tank body bottom tray 9 is connected with the adsorption tank body 5 through a bolt 6, a grid ring 12 is arranged between the upper sealing stop block 2 and the coal sample, a felt 11, a sealing ring 3 and a.
One end of the gas storage tank 22 is connected to a gas circulation interface 8 of the adsorption tank body 5, the adsorption tank body 5 is arranged in a constant-temperature air bath 26 environment, and a rotary platform is arranged below the adsorption tank body 5;
an X-ray source 27 and a ray detector 29 which are opposite to the adsorption tank body are fixedly arranged in the constant-temperature air bath 26, the ray detector 29 is connected to a data acquisition and analysis system, and a gas mass flow meter 25 and a gas pressure sensor II 24 are arranged on a pipeline connecting the adsorption tank body 5 and the gas storage tank;
the other end of the gas storage tank 22 is connected to one end of a gas pressure regulating valve 21, the other end of the gas pressure regulating valve 21 is connected to a first port of a three-way valve 16, and a second port of the three-way valve 16 is connected to a gas source 13 through a gas needle valve I15 and a gas pressure reducing valve 14;
the third port of the three-way valve 16 is connected to a roots vacuum pump 18 through a gas needle valve ii 17.
A gas pressure sensor I23 is arranged between the front end and the rear end of the gas storage tank 22, and a vacuum thermocouple meter 19 and a vacuum diaphragm valve 20 are further arranged on the Roots vacuum pump.
An air outlet valve is also arranged at one end of the air storage tank 22 connected with the adsorption tank body 5.
The rotary stage 30 is provided on a multi-axis mechanical movement device 31, and the multi-axis mechanical movement device 31 is provided on an optical stage 32.
The method for synchronously measuring the coal rock adsorption gas quantity, deformation and porosity comprises the following steps:
s1: preparing a coal sample drilled under a coal mine into a required circular cylinder, and then polishing the surface of the coal sample by using abrasive paper to flatten the surface of the coal sample;
s2: putting the prepared coal sample into a vacuum drying oven for drying treatment for more than 24h, finally measuring the size of the coal sample, and recording the mass M, the radius R, the height L and the volume V of the coal sample0＝π×R2XL, and placing into a marked sealing bag for storage for use in experiments; before the experiment, the volume of the gas storage tank 22 and the pipeline connected with the adsorption tank body 5 is calibrated, and the volume of the gas storage tank 22 is recorded as VcThe volume of the pipeline connected between the gas storage tank 22 and the adsorption tank body 5 is Vg；
S3: putting the coal sample 1 into an adsorption tank body 5, wherein the size of the inner wall of the adsorption tank body 5 is equivalent to that of the coal sample 1, and the rigid inner wall of the adsorption tank body 5 forms annular surface constraint on the coal sample 1 to limit annular strain generated in the experimental process of the coal sample 1;
s4: after the coal sample 1 is placed in the adsorption tank body 5, the bolt 6 of the connecting flange 10 of the adsorption tank body 5 is screwed down, and the adsorption tank body 5 is sealed; further, the adsorption tank body 5 is sealed, and the adsorption tank body 5 is sealed by adopting a method of combining a groove arranged on the connecting flange 10 with the rubber sealing ring 3; starting the press machine to enable the upper sealing stop block 2 to generate displacement and to be in contact with the upper end face of the coal sample 1, and then closing the press machine to enable the upper sealing stop block 2 to stop moving; further, a felt 11 is arranged between the upper sealing stop block 2 and the upper end face of the coal sample 1 to prevent the upper end face of the coal sample 1 from being uneven, so that the coal sample 1 is unbalanced in loading; the volume of the felt 11 is calibrated before the experiment and is marked as Vm(ii) a At the same time, the volume of the adsorption tank body 5 at the moment is recorded as Vx0；
S5: after the adsorption tank body 5 is sealed, a gas circulation interface 8 arranged on a tray 9 at the bottom of the adsorption tank body is connected with a mass flowmeter 25 through a gas pipeline; then, communicating the gas storage tank 22 with the whole gas pipeline, closing the gas needle valve I15, opening the gas needle valve II 17, communicating the adsorption tank body 5 filled with the coal sample 1 with the Roots vacuum pump 18, and starting the Roots vacuum pump 18 to perform degassing treatment on the coal sample 1; the device is used for eliminating the influence of the coal sample 1 on the experimental result due to the fact that the coal sample 1 adsorbs air in the process of the device coal sample 1;
s6: the thermocouple 19 to be vacuumed shows a value lower than 4X 10-1After Pa, closing the gas needle valve II 17 and the Roots vacuum pump 18 in sequence, and stopping degassing the coal sample in the adsorption tank body 5;
s7: setting the gas pressure regulating valve 21 to make the numerical value of the outlet pressure of the gas pressure regulating valve be an experimental requirement parameter; a gas pressure reducing valve 14 and a gas needle valve I15 which are connected with a gas source 13 are opened in sequence, so that high-pressure gas enters a gas storage tank 22 through a pipeline; the air storage tank 22 is provided with an air inlet valve and an air outlet valve; after the index of the gas pressure sensor I23 to be arranged on the gas storage tank is the experimental requirement value, the pressure value P is recorded1Then, the gas mass flow meter 25 is started, and a gas outlet valve arranged on the gas storage tank 22 is opened, so that the high-pressure gas enters the adsorption tank body through a gas pipeline; starting the air bath to make the temperature of the air bath be the temperature T required by the experiment;
s8: starting the press again to enable the upper sealing stop block 2 to move and apply axial stress to the coal sample; the axial stress applied to the coal sample 1 by the press machine is recorded after the numerical value of the axial stress is an experimental preset numerical value delta, the moving distance delta L of the upper sealing stop block 2 is recorded, and at the moment, the volume V of the coal sample 1P2＝π×R2XLX (1-. DELTA.L). Then, the coal sample 1 fully absorbs high-pressure gas under the condition of axial loading; at the same time, the volume of the adsorption tank body 5 at the moment is recorded as VxP；
S9: after the readings of the gas mass flow meter 25 are continuously stable for 12 hours, and the readings of the gas pressure sensor I and the gas pressure sensor II are equal, the coal sample 1 is considered to be in balance with the adsorbed gas; at this time, the accumulated amount Q of the gas mass flow meter 25 is recorded0Reading P of gas pressure sensor2；
S10: after the coal sample 1 is balanced in gas adsorption, the rotary platform 30, the X-ray source 27 and the ray detector 29 are started to scan the porosities of different layers of the coal sample, and the porosity numerical values of the different layers are averaged to obtain the adsorption balance pressure P2Average porosity Φ; at this time, the pore volume per unit mass of coal was Vk＝[Φ×π×R2×L×(1-ΔL)](ii) a/M; then the pressure P is equalized2When the temperature of the water is higher than the set temperature,the free gas content in the coal sample is:
in the formula: wyP2At equilibrium pressure P for high-pressure gas2Free gas content m in the coal sample3/t；T0、P0Absolute temperature and absolute pressure in a standard state are 273K and 0.101325MPa respectively; t is the absolute temperature in the air bath, K, during the experiment; vkPore volume per unit mass of coal, m3/t；Z2At equilibrium pressure P for high-pressure gas2The compression factor of time.
S11: further can calculate the equilibrium pressure P of the adsorbed gas2The molar quantity n of the adsorbed gas of the coal sample1Comprises the following steps:
in the formula: z1Is a high-pressure gas with a pressure of P1The compression factor of the gas; n is1To balance the pressure P for the gas2In this case, the coal sample absorbs the molar amount of the gas.
Further obtaining the gas balance pressure P2In the process, the adsorbed gas content of the coal sample is as follows:
the method for measuring the residual adsorption quantity of the coal sample comprises the following steps:
s12: at the completion of gas equilibrium pressure P2Under the condition, after the free gas content and the adsorbed gas content of the coal sample are measured, a pipeline connected between an air inlet valve of the air storage tank and a gas pressure regulating valve is immediately disassembled, so that the coal sample in the adsorption tank body is subjected to gas diffusion under normal pressure, and the gas diffusion amount under different diffusion time is recorded through a gas mass flowmeter. Up to the gasThe reading of the mass flow meter is displayed as 0ml/min, and the coal sample can be considered to be finished releasing the gas. At this time, the gas mass flowmeter integrated quantity Q is recordedf；
S13: repeating S10 to obtain the porosity phi after the coal sample gas emission is finishedmWill phimSubstituting the obtained value into the formula (1) to obtain the free gas content W of the coal sample after the gas emission is finishedyP2m(ii) a The free gas content W of the coal sampleyP2mMultiplying the mass M of the coal sample by the mass M of the coal sample to obtain the amount of free gas after the gas is released; further, the residual adsorption amount of
WxP2c＝Q0-Qf-WyP2m×M(4)
S14: and repeating the steps S5-S11 to obtain the free gas content and the adsorbed gas content of the coal sample under different adsorbed gas balance pressures and different axial loading conditions.
Finally, it is noted that the above-mentioned preferred embodiments illustrate rather than limit the invention, and that, although the invention has been described in detail with reference to the above-mentioned preferred embodiments, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the scope of the invention as defined by the appended claims.
Claims (5)
1. The method for correcting the calculation of the free amount of the coal bed gas and measuring the residual adsorption amount is characterized by comprising the following steps of: the device is implemented based on correction of coal bed gas free amount calculation and residual adsorption amount measurement, and comprises an adsorption tank body, a gas pressure reducing valve, a Roots vacuum pump, a gas pressure regulating valve and a gas storage tank;
the adsorption tank body is used for storing a coal sample, an upper sealing stop block is arranged at the upper end of the adsorption tank body and connected to a press machine, the lower end of the adsorption tank body is connected to a bottom tray of the adsorption tank body through a connecting flange, and a gas circulation interface is arranged on the bottom tray of the adsorption tank body;
one end of the gas storage tank is connected to an adsorption tank body, the adsorption tank body is arranged in a constant-temperature air bath environment, and a rotary platform is arranged below the adsorption tank body;
an X-ray source and a ray detector which are opposite to the adsorption tank body are fixedly arranged in the constant-temperature air bath, the ray detector is connected to a data acquisition and analysis system, and a gas mass flow meter and a gas pressure sensor II are arranged on a pipeline connecting the adsorption tank body and the gas storage tank;
the other end of the gas storage tank is connected to one end of a gas pressure regulating valve, the other end of the gas pressure regulating valve is connected to a first port of a three-way valve, and a second port of the three-way valve is connected to a gas source through a gas needle valve I and a gas pressure reducing valve;
the third port of the three-way valve is connected to the roots vacuum pump through a gas needle valve II; a gas pressure sensor I is arranged between the front end and the rear end of the gas storage tank, a vacuum thermocouple meter is also arranged on the Roots vacuum pump, and a gas outlet valve is also arranged at one end of the gas storage tank, which is connected with the adsorption tank body;
the connecting flange is provided with a groove, and the upper end of the adsorption tank body is also provided with a sealing ring;
the rotary platform is arranged on a multi-axis mechanical moving device, and the multi-axis mechanical moving device is arranged on the optical platform;
the method comprises the following steps:
s1: preparing and molding the drilled coal sample, and then polishing the surface of the coal sample by using sand paper to flatten the surface of the coal sample;
s2: placing the prepared coal sample into a vacuum drying oven for drying treatment, and then measuring the size of the coal sample;
s3: calibrating the volume of the gas storage tank and the pipeline connected with the adsorption tank body, and recording the volume of the gas storage tank asV cThe volume of the pipeline connected between the gas storage tank and the adsorption tank body isV g；
S3: putting a coal sample into an adsorption tank body, sealing the adsorption tank body, starting a press machine to enable an upper sealing stop block to generate displacement and to be in contact with the upper end face of the coal sample, then closing the press machine to enable the upper sealing stop block to stop moving, placing a felt between the upper sealing stop block and the upper end face of the coal sample, and recording the felt volume asV mRecord the canister at that timeVolume of the body isV x0；
S4: after the adsorption tank body is sealed, opening a gas needle valve II, closing a gas needle valve I, and degassing the whole tank body and a pipeline through a vacuum pump;
s5: when the vacuum thermocouple meter on the vacuum pump displays that the set threshold value is reached, the vacuum pump is closed, and the coal sample in the adsorption tank body is stopped from being degassed;
s6: adjusting a gas pressure regulating valve, enabling the pressure value of an outlet of the gas pressure regulating valve to reach a set threshold value, opening a gas needle valve I and a gas pressure reducing valve, enabling high-pressure gas to enter a gas storage tank through a pipeline, and recording the pressure value P when the numerical value of a gas pressure sensor I on the gas storage tank reaches the set threshold value1Then, opening a gas mass flowmeter and a gas outlet valve on a gas storage tank to enable high-pressure gas to enter the adsorption pipe body through a gas pipeline, and opening an air bath;
s7: the press machine is started again to enable the upper sealing stop block to move, axial stress is applied to the coal sample, and after the axial stress reaches a specified value, the moving distance of the upper sealing stop block is recordedΔLMeanwhile, the coal sample fully absorbs high-pressure gas under the loaded condition, and the volume of the adsorption tank body at the moment is recordedV xP；
S8: after the gas mass flowmeter is stable for a specified time interval, and the readings of the gas pressure sensor I and the gas pressure sensor II are the same, at the moment, the coal sample is considered to be adsorbed with gas balance, and the accumulated quantity Q of the gas mass flowmeter at the moment is recorded0And gas pressure sensor readingsP 2；
S9: starting the rotary platform, the X-ray source and the ray detector to scan the porosities of different layers of the coal sample, and averaging the porosity numerical values of different layers to obtain adsorption equilibrium pressureP 2Average porosity ofΦCalculating the content of free gas in the coal sample, the molar quantity of the adsorbed gas of the coal sample and the content of the adsorbed gas of the coal sample;
s10: the pipeline connected between the air inlet valve and the gas pressure regulating valve of the gas storage tank is removed, so that the coal sample in the adsorption tank body is released under normal pressure,recording the gas diffusion amount under different diffusion time through the gas mass flowmeter until the reading of the gas mass flowmeter is displayed as 0ml/min, and recording the accumulated amount of the gas mass flowmeterQ f；
S11: step S9 is executed to obtain the porosity of the coal sample after the gas emission is finishedΦ mAnd calculating the content of the free gas of the coal sample after the gas is diffused, the amount of the free gas after the gas is diffused and the residual adsorption amount.
2. The method for correcting the calculation of free amount of coal bed gas and measuring the residual adsorption amount according to claim 1, wherein: also comprises
S12: and repeating the steps S4-S9 to obtain the free gas content and the adsorbed gas content of the coal sample under different adsorbed gas balance pressures and different axial loading conditions.
3. The method for correcting the calculation of free amount of coal bed gas and measuring the residual adsorption amount according to claim 1, wherein: the drying time in step S2 is 24h or more, and the set threshold value reached as indicated by the vacuum thermocouple in step S5 is 4X 10-1Pa, step S8 specifies a time interval of 12 h.
4. The method for correcting the calculation of free amount of coal bed gas and measuring the residual adsorption amount according to claim 1, wherein: in step S9, the free gas content in the coal sample, the molar quantity of the adsorbed gas in the coal sample, and the adsorbed gas content in the coal sample are respectively:
wherein the content of the first and second substances,W yP2at equilibrium pressure for high pressure gasP 2In the meantime, the content of free gas in the coal sample,T 0、P 0respectively, absolute temperature and absolute pressure in a standard state,Tis the absolute temperature in the air bath,V kas coal per unit massThe volume of the pores is increased, and the pore volume is increased,V k=[Φ×π×R 2 ×L×（1-ΔL）]m, M is the mass of the coal sample, L is the height of the coal sample, R is the radius of the coal sample,Z 2at equilibrium pressure for high pressure gasP 2A compression factor of time;
wherein the content of the first and second substances,n 1to balance the pressure for gasP 2When the coal sample is used, the coal sample absorbs the molar weight of the gas,Z 1is a high pressure gas pressure ofP 1The compression factor of the gas;
wherein
The adsorbed gas content of the coal sample.
5. The method for correcting the calculation of free amount of coal bed gas and measuring the residual adsorption amount according to claim 4, wherein: and (S11) after the gas is released in the step S11, the residual adsorption capacity of the free gas in the coal sample is as follows:
wherein the content of the first and second substances,W yP2mthe content of free gas in the coal sample after the gas emission is finished.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810012086.8A CN108303509B (en) | 2018-01-05 | 2018-01-05 | Device and method for correcting free amount calculation of coal bed gas and measuring residual adsorption amount |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810012086.8A CN108303509B (en) | 2018-01-05 | 2018-01-05 | Device and method for correcting free amount calculation of coal bed gas and measuring residual adsorption amount |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN108303509A CN108303509A (en) | 2018-07-20 |
| CN108303509B true CN108303509B (en) | 2021-03-16 |
Family
ID=62868566
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201810012086.8A Active CN108303509B (en) | 2018-01-05 | 2018-01-05 | Device and method for correcting free amount calculation of coal bed gas and measuring residual adsorption amount |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN108303509B (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109187266B (en) * | 2018-09-14 | 2021-07-20 | 中煤科工集团重庆研究院有限公司 | Gas loss compensation model experiment system and method for directly measuring gas content |
| CN111122417B (en) * | 2020-02-22 | 2022-06-21 | 太原理工大学 | Device and method for measuring total volume expansion rate of open-close hole of coal containing gas |
| CN113702261B (en) * | 2021-08-25 | 2023-11-03 | 山东科技大学 | Test analysis method for correcting porosity and deformation of gas-containing coal |
| CN114062191A (en) * | 2021-11-17 | 2022-02-18 | 中国地质大学（北京） | Displacement adsorption experimental device and experimental method for binary gas in porous medium |
| CN115541449B (en) * | 2022-11-30 | 2023-03-10 | 煤炭科学技术研究院有限公司 | Underground coal seam gas content measuring method and device and electronic equipment |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103776722B (en) * | 2013-12-31 | 2016-09-21 | 河南理工大学 | The coal seam gas-bearing capacity method of testing of sampling under subnormal ambient |
| CN105571979B (en) * | 2015-12-18 | 2018-04-13 | 河南理工大学 | Stand under load tectonic soft coal gas adsorption desorption experiment system and method |
| CN107202744B (en) * | 2017-05-27 | 2019-09-03 | 中煤科工集团重庆研究院有限公司 | A kind of coal petrography absorption deformation and porosity synchronous measurement device and method |
| CN107101928A (en) * | 2017-05-27 | 2017-08-29 | 中煤科工集团重庆研究院有限公司 | A kind of non-linear device for testing permeability coefficient of coal petrography and method |
-
2018
- 2018-01-05 CN CN201810012086.8A patent/CN108303509B/en active Active
Also Published As
| Publication number | Publication date |
|---|---|
| CN108303509A (en) | 2018-07-20 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN108303509B (en) | Device and method for correcting free amount calculation of coal bed gas and measuring residual adsorption amount | |
| CN107860681B (en) | Gas adsorption and desorption characteristic testing device and method for pre-adsorbing moisture coal sample | |
| CN103994943B (en) | A kind of coal/shale adsorption isotherm experiment device | |
| CN103940722B (en) | The proving installation of a kind of gas bearing shale factor of porosity and absorption parameter and method | |
| CN101629891B (en) | Fixedly coupled three-shaft servo seepage pressure chamber containing gas coal thermal flow | |
| CN101634621B (en) | Fluid-solid-heat coupling triaxial servo percolation device for gas-contained coal | |
| CN205138940U (en) | Test coal body gas adsorbs desorption heat effect experimental system | |
| CN103776979B (en) | A kind of coal seam water infusion suppresses analog detection method and the device of desorption of mash gas effect | |
| CN101408493B (en) | Method and apparatus for measuring adsorbance-deformation-permeability coefficients of material | |
| CN209745750U (en) | Deformation-adsorption capacity synchronous testing device in gas adsorption process of coal body | |
| CN109870364A (en) | Stress-seepage coupling acts on the experimental rig and method of lower Rock And Soil | |
| CN108801879B (en) | Shale matrix particle porosity and permeability integrated measurement system and method | |
| CN109946215A (en) | A kind of original position coal body gas absorption amount test simulator | |
| WO2022161137A1 (en) | System for measuring dynamic physical properties of rock | |
| CN203929583U (en) | The proving installation of a kind of gas bearing shale factor of porosity and absorption parameter | |
| CN108732329B (en) | Coal seam gas pressure measurement simulation experiment device and method | |
| Wang et al. | Seepage law and permeability calculation of coal gas based on Klinkenberg effect | |
| CN111238988B (en) | Experimental device and method for measuring efficiency of supercritical carbon dioxide in dense oil core to replace crude oil | |
| CN205958207U (en) | Tire tube or inner liner gas tightness survey device | |
| CN209911168U (en) | Isothermal adsorption/desorption and displacement test equipment under rock covering and pressing condition | |
| CN113624654B (en) | Rock porosity measuring device and method | |
| CN111323359A (en) | Device and method for measuring spontaneous imbibition of rock core of high-pressure natural gas-water system | |
| CN113670768B (en) | Method, device and system for determining sea phase shale in-situ gas volume recovery | |
| CN114047105B (en) | Device and method for testing porosity of high-pressure helium shale | |
| CN114894671A (en) | Coal body methane adsorption time measuring method based on diffusion-seepage decoupling experiment |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |