CN116879109A - Coal bed gas-bearing experiment system and method based on pre-pressurization and carbon fractionation technology - Google Patents
Coal bed gas-bearing experiment system and method based on pre-pressurization and carbon fractionation technology Download PDFInfo
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- 239000003245 coal Substances 0.000 title claims abstract description 35
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 34
- 229910052799 carbon Inorganic materials 0.000 title claims abstract description 34
- 238000000034 method Methods 0.000 title claims abstract description 24
- 238000005194 fractionation Methods 0.000 title claims abstract description 23
- 238000005516 engineering process Methods 0.000 title claims abstract description 15
- 238000002474 experimental method Methods 0.000 title claims description 53
- 239000000203 mixture Substances 0.000 claims abstract description 12
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 9
- 238000012360 testing method Methods 0.000 claims abstract description 7
- 238000003860 storage Methods 0.000 claims description 29
- 239000011435 rock Substances 0.000 claims description 28
- 238000002347 injection Methods 0.000 claims description 12
- 239000007924 injection Substances 0.000 claims description 12
- 230000008569 process Effects 0.000 claims description 7
- 238000001514 detection method Methods 0.000 claims description 6
- 238000011049 filling Methods 0.000 claims description 6
- 238000002156 mixing Methods 0.000 claims description 5
- 238000004458 analytical method Methods 0.000 claims description 4
- 239000004215 Carbon black (E152) Substances 0.000 claims description 3
- 238000006073 displacement reaction Methods 0.000 claims description 3
- 230000000694 effects Effects 0.000 claims description 3
- 238000010438 heat treatment Methods 0.000 claims description 3
- 229930195733 hydrocarbon Natural products 0.000 claims description 3
- 150000002430 hydrocarbons Chemical class 0.000 claims description 3
- 238000011068 loading method Methods 0.000 claims description 3
- 238000003825 pressing Methods 0.000 claims description 3
- 238000012544 monitoring process Methods 0.000 claims description 2
- 238000002360 preparation method Methods 0.000 claims description 2
- 238000005086 pumping Methods 0.000 claims description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 abstract description 24
- 238000011065 in-situ storage Methods 0.000 abstract description 10
- 238000004364 calculation method Methods 0.000 abstract description 5
- 238000011156 evaluation Methods 0.000 abstract description 4
- 238000011161 development Methods 0.000 abstract description 3
- 238000009472 formulation Methods 0.000 abstract description 3
- 239000007789 gas Substances 0.000 description 118
- 238000001179 sorption measurement Methods 0.000 description 8
- 238000011160 research Methods 0.000 description 4
- 238000003795 desorption Methods 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 230000009471 action Effects 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000004868 gas analysis Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000013508 migration Methods 0.000 description 1
- 230000005012 migration Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N7/00—Analysing materials by measuring the pressure or volume of a gas or vapour
- G01N7/14—Analysing materials by measuring the pressure or volume of a gas or vapour by allowing the material to emit a gas or vapour, e.g. water vapour, and measuring a pressure or volume difference
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/0005—Field flow fractionation
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- 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
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P90/00—Enabling technologies with a potential contribution to greenhouse gas [GHG] emissions mitigation
- Y02P90/70—Combining sequestration of CO2 and exploitation of hydrocarbons by injecting CO2 or carbonated water in oil wells
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Abstract
The invention discloses a coal bed gas-containing experimental system and a method based on a pre-pressurizing and carbon fractionating technology, which are characterized in that a coal core is restored to a reservoir in-situ state in a pre-pressurizing mode according to a gas-containing component, water content and reservoir pressure of coal bed gas, and the desorbed gas content is the coal bed in-situ gas content, so that calculation of loss gas content can be avoided, and the testing precision is greatly improved; meanwhile, the occurrence state of the coalbed methane is identified based on the carbon fractionation technology, the in-situ gas content of the coalbed methane reservoir and the occurrence state of the identified gas can be accurately calculated, and the method has a certain guiding significance for resource evaluation and development scheme formulation of the coalbed methane.
Description
Technical Field
The invention particularly relates to the technical field of coal bed gas-containing experiments, in particular to a coal bed gas-containing experiment system and method based on pre-pressurization and carbon fractionation technology.
Background
The coalbed methane is mainly stored in the coal reservoir in an adsorption state and a free state, particularly low-rank coalbed methane and deep coalbed methane, and the content ratio of the free gas is high but cannot be ignored, so that the prediction of the gas content and the identification of the occurrence state have important research values for the resource quantity evaluation and development scheme formulation of the coalbed methane; in the conventional coring process, the lifting time of the core in the shaft is long, so that the loss gas quantity is large, the in-situ gas content of the coal reservoir is difficult to accurately calculate by the conventional method, and the occurrence state of the coalbed methane cannot be accurately identified.
The method for acquiring the gas content of the coal bed gas mainly comprises the steps of on-site desorption test, isothermal adsorption experiment, well logging explanation and the like; the gas content field test is a main test method, can directly reflect the adsorption gas content, but has higher cost and inaccurate calculation of the loss gas; the maximum value of the adsorption gas quantity obtained by the isothermal adsorption experiment can only be used as a reference for gas content research; the logging interpretation method has the advantages of multiple influencing factors and high cost; therefore, the conventional research method for the gas content of the coal bed gas has the problems of high cost, inaccurate calculation result and the like.
In the coal bed gas resource evaluation potential process, in-situ gas content and adsorbed gas/free gas ratio are two important parameters. The free gas lost in the coring process of the coal rock is not easy to accurately calculate, the rock core can be restored to the in-situ state of the reservoir stratum in a pressurizing mode according to the gas component, the water content and the reservoir stratum pressure of the coal bed gas, and thus the gas content desorbed by the rock core is the in-situ gas content of the coal reservoir stratum, and the calculation of the gas loss can be avoided; meanwhile, the carbon isotope fractionation can effectively distinguish the migration processes of gases in different occurrence states, and can be used for identifying the occurrence state of gas; during desorption/production of coalbed methane, carbon isotope fractionation presents the following 4 stages:
a. the gas produced in the free air pressure difference seepage stage is mainly free air delta 13 C 1 The value remains substantially unchanged and is equal to the air supply value (delta 13 C 1 0 ) Close;
b. in the adsorption-free conversion stage, the free gas proportion is reduced, the adsorbed gas proportion is increased, delta 13 C 1 The value becomes light gradually, and the adsorption gas takes the dominant place along with the consumption of a large amount of free gas;
c. adsorption gas analysis stage delta 13 C 1 The value becomes progressively heavier;
d. in the concentration difference diffusion stage, the adsorption gas remained in the coal-rock matrix is outwards diffused delta under the action of concentration difference 13 C 1 The value again lightens and eventually stabilizes at a lighter value.
Based on the above principle, the carbon fractionation technology provides a research thought for identifying occurrence state of coal bed gas, so that a coal bed gas-containing experimental system and method based on pre-pressurization and carbon fractionation technology are necessary to solve the defects in the prior art.
Disclosure of Invention
In order to achieve the above purpose, the present invention provides the following technical solutions: the utility model provides a coal seam gas-bearing experimental system based on pre-pressurization and carbon fractionation technique, its includes the rock core holder that is used for the centre gripping rock core, the rock core holder is placed in the accuse temperature case, the entry end of rock core holder is connected with gas injection device, the upper end of rock core holder is connected with evacuating device, the exit end of rock core holder has connected gradually back pressure valve and gas metering analysis device, just be connected with pressure control device between rock core holder and the back pressure valve.
Further, preferably, a first intermediate container is connected between the gas injection device and the core holder, a seventh valve is connected between the first intermediate container and the inlet end of the core holder, and a tenth pressure gauge and a fourth thermometer are arranged at the top end of the first intermediate container.
Further, preferably, the gas injection means comprises three branches, wherein,
the first branch is provided with a first gas cylinder filled with hydrocarbon gas, the outlet end of the first gas cylinder is sequentially connected with a first valve, a first pressure gauge, a first booster pump, a first storage tank, a second valve, a third pressure gauge and a first flowmeter through pipelines, the first booster pump is also connected with a first air compressor, and the top of the first storage tank is connected with a second pressure gauge and a first thermometer;
the second branch is provided with N charges 2 The outlet end of the second air bottle is sequentially connected with a third valve, a fourth pressure gauge, a second booster pump, a second storage tank, a fourth valve, a sixth pressure gauge and a second flowmeter through pipelines, the second booster pump is also connected with a second air compressor, and the top of the second storage tank is connected with a fifth pressure gauge and a second thermometer;
the third branch is provided with CO filling 2 The outlet end of the third gas cylinder is sequentially connected with a fifth valve, a seventh pressure gauge, a third booster pump, a third storage tank, a sixth valve, a ninth pressure gauge and a third flowmeter through pipelines, the third booster pump is further connected with a third air compressor, and the top of the third storage tank is connected with an eighth pressure gauge and a third thermometer.
Further, preferably, the vacuum pumping device comprises a tenth third valve and a vacuum pump, and the vacuum pump and the tenth third valve are sequentially arranged on a pipeline at the upper end of the core holder from bottom to top.
Further, preferably, the gas meter analysis device is composed of a filter, a fourth flowmeter, and CH 4 Gas infrared on-line analyzer and CO 2 Infrared rayThe gas on-line analyzer, the second intermediate container, the twelfth valve, the fifth flowmeter, the carbon isotope analyzer and the air bag are sequentially connected through pipelines, wherein the carbon isotope analyzer is connected with a computer.
Further, preferably, a twelfth pressure gauge and a fifth thermometer are arranged on the top of the second intermediate container.
Further, as an optimization, the pressure control device comprises a hand pump, an eighth valve and a buffer tank, wherein the hand pump, the eighth valve and the buffer tank are sequentially connected through pipelines and then are divided into three branches, the first branch is connected with the buffer tank and the ninth valve and then is connected with the left side of the core holder, and the axial pressure is controlled; the second branch is used for connecting the buffer tank with the tenth valve and then with the side surface of the core holder, so as to control confining pressure; the third branch is used for connecting the buffer tank with an eleventh valve and a back pressure valve and controlling the back pressure;
an eleventh pressure gauge is arranged at the top of the buffer tank.
A coal seam gas-bearing experimental method based on pre-pressurization and carbon fractionation techniques, comprising the steps of:
step 1: checking air tightness; after the system is connected, after equipment is cleaned, all parts of the system are inspected, inlet and outlet valves are closed, and the air tightness of the device is inspected;
step 2: testing the gas composition in the core; measuring the gas component in the core by a gas chromatograph;
step 3: loading a sample and vacuumizing; filling a rock sample into a core holder, opening a vacuum pump, a tenth valve, a second valve, a fourth valve, a sixth valve and a twelfth valve, and evacuating air in the system, so that the interference of the exhaust air on experimental effect is eliminated, and the preparation is made for experiments; after vacuumizing, closing the vacuum pump, the tenth valve, the second valve, the fourth valve, the sixth valve and the twelfth valve;
step 4: adding shaft pressure and confining pressure;
and (5) shaft pressing: after opening the eighth valve and the ninth valve, injecting water into the core holder through a hand pump, and compacting a sample in the core holder; according to the requirement of an experimental scheme, after the axial pressure required by the experiment is increased, closing the ninth valve;
and (3) confining pressure: opening a tenth valve, injecting water into the core holder through a hand pump, and compacting a sample in the core holder; according to the requirement of an experimental scheme, after the confining pressure required by the experiment is increased, closing a tenth valve;
step 5: back pressure and temperature are added;
and (3) adding back pressure: opening an eleventh valve according to the requirement of an experimental scheme, and increasing the pressure of the back pressure valve to the pressure required by the experiment;
heating: according to the requirement of an experimental scheme, the temperature of the temperature control box is adjusted to be required by the experiment;
step 6: saturation; according to the gas composition in the tested core, CH is added 4 、N 2 And CO 2 Pressurizing the gas to the pressure required by the experiment, and injecting the gas into a first intermediate container for standby;
opening CH 4 Gas cylinder, first valve, first air compressor, first booster pump, will CH 4 Pressurizing the gas to the pressure required by the experiment, storing the gas in a first storage tank, and closing a first valve after pressurizing is completed;
turning on CO 2 The gas cylinder, the third valve, the second air compressor and the second booster pump are used for mixing CO 2 Pressurizing the gas to the pressure required by the experiment, storing the gas in a second storage tank, and closing a third valve after pressurizing is completed;
turn on N 2 The gas cylinder, the fifth valve, the third air compressor and the third booster pump are used for mixing CO 2 Pressurizing the gas to the pressure required by the experiment, storing the gas in a third storage tank, and closing a fifth valve after pressurizing is completed;
opening a second valve, a fourth valve and a sixth valve, injecting the gas into the first intermediate container according to the gas composition in the core, and monitoring through a first flowmeter, a second flowmeter and a third flowmeter;
after the steps are finished, a seventh valve is opened, and the prepared mixed gas is injected into the core holder;
step 7: experiment metering and detection;
metering: through a fourth flowmeter, CH 4 Infrared analyzer, CO 2 Infrared gas separationA gas analyzer for measuring gas flowing from the core holder;
and (3) detection: in the experimental process, the twelfth valve, the carbon isotope analyzer and the computer are opened, so that the delta in the core can be detected in real time 13 C 1 Values to determine free and adsorbed gas in the core;
step 8: changing the conditions and continuing to carry out a comparison experiment: according to the needs of experimental purposes, the conditions such as experimental temperature, axial pressure back pressure, gas mixing proportion, injection displacement and the like are changed according to different rock samples, and comparison experiments under other experimental conditions are developed in the same way.
Compared with the prior art, the invention has the following beneficial effects: according to the invention, the coal core is restored to the in-situ state of the reservoir by a pre-pressurizing mode according to the gas content component, the water content and the reservoir pressure of the coal bed gas, and the desorbed gas content is the in-situ gas content of the coal bed, so that the calculation of the loss gas content can be avoided, and the test precision is greatly improved; meanwhile, the occurrence state of the coalbed methane is identified based on the carbon fractionation technology, the in-situ gas content of the coalbed methane reservoir and the occurrence state of the identified gas can be accurately calculated, and the method has a certain guiding significance for resource evaluation and development scheme formulation of the coalbed methane.
Drawings
FIG. 1 is a schematic diagram of a coal bed gas-bearing experimental system based on pre-pressurization and carbon fractionation techniques;
FIG. 2 is an experimental flow chart of a coal bed gas-bearing experimental method based on pre-pressurization and carbon fractionation techniques.
In the figure: 1. a first gas cylinder; 2. a first valve; 3. a first pressure gauge; 4. a first air compressor; 5. a first booster pump; 6. a first storage tank; 7. a second pressure gauge; 8. a first thermometer; 9. a second valve; 10. a third pressure gauge; 11. a first flowmeter; 12. a second gas cylinder; 13. a third valve; 14. a fourth pressure gauge; 15. a second air compressor; 16. a second booster pump; 17. a second storage tank; 18. a fifth pressure gauge; 19. a second thermometer; 20. a fourth valve; 21. a sixth pressure gauge; 22. a second flowmeter; 23. a third gas cylinder; 24. a fifth valve; 25. a seventh pressure gauge; 26. a third air compressor; 27. a third booster pump; 28.a third tank; 29. an eighth pressure gauge; 30. a third thermometer; 31. a sixth valve; 32. a ninth pressure gauge; 33. a third flowmeter; 34. a first intermediate container; 35. a tenth pressure gauge; 36. a fourth thermometer; 37. a seventh valve; 38. a temperature control box; 39. a core holder; 40. hand-operated pump; 41. an eighth valve; 42. a buffer tank; 43. an eleventh pressure gauge; 44. a ninth valve; 45. a tenth valve; 46. an eleventh valve; 47. a back pressure valve; 48. a filter; 49. a fourth flow meter; 50. CH (CH) 4 A gas infrared on-line analyzer; 51. CO 2 An infrared gas on-line analyzer; 52. a second intermediate container; 53. a twelfth pressure gauge; 54. a fifth thermometer; 55. a twelfth valve; 56. a fifth flowmeter; 57. a carbon isotope analyzer; 58. a computer; 59. an air bag; 60. a vacuum pump; 61. and a tenth valve.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Examples: referring to fig. 1 and 2, the present invention provides a technical solution: the utility model provides a coal seam gas-bearing experimental system based on pre-pressurization and carbon fractionation technique, it includes the rock core holder 39 that is used for the centre gripping rock core, and the rock core holder 39 is placed in the accuse temperature case 38, and the entry end of rock core holder 39 is connected with gas injection device, and the upper end of rock core holder 39 is connected with evacuating device, and the exit end of rock core holder 39 has connected gradually back pressure valve 47 and gas measurement analytical equipment, and is connected with pressure control device between rock core holder 39 and the back pressure valve 47.
In this embodiment, a first intermediate container 34 is connected between the gas injection device and the core holder 39, and a seventh valve 37 is connected between the first intermediate container 34 and the inlet end of the core holder 39, and a tenth pressure gauge 35 and a fourth thermometer 36 are provided at the top end of the first intermediate container 34.
In this embodiment, the gas injection means comprises three branches, wherein,
a first gas cylinder 1 filled with hydrocarbon gas is arranged on the first branch, the outlet end of the first gas cylinder 1 is sequentially connected with a first valve 2, a first pressure gauge 3, a first booster pump 5, a first storage tank 6, a second valve 9, a third pressure gauge 10 and a first flowmeter 11 by adopting pipelines, the first booster pump 5 is also connected with a first air compressor 4, and the top of the first storage tank 6 is connected with a second pressure gauge 7 and a first thermometer 8;
the second branch is provided with N charges 2 The outlet end of the second gas cylinder 12 is sequentially connected with a third valve 13, a fourth pressure gauge 14, a second booster pump 16, a second storage tank 17, a fourth valve 20, a sixth pressure gauge 21 and a second flowmeter 22 by adopting pipelines, the second booster pump 16 is also connected with a second air compressor 15, and the top of the second storage tank 17 is connected with a fifth pressure gauge 18 and a second thermometer 19;
the third branch is provided with CO filling 2 The outlet end of the third air bottle 23 is connected with a fifth valve 24, a seventh pressure gauge 25, a third booster pump 27, a third storage tank 28, a sixth valve 31, a ninth pressure gauge 32 and a third flowmeter 33 in sequence by adopting pipelines, the third booster pump 27 is also connected with a third air compressor 26, and the top of the third storage tank 28 is connected with an eighth pressure gauge 29 and a third thermometer 30.
In this embodiment, the vacuumizing device includes a tenth valve 61 and a vacuum pump 60, and the vacuum pump 60 and the tenth valve 61 are sequentially disposed on a pipeline at the upper end of the core holder 39 from bottom to top.
In the present embodiment, the gas meter analyzer includes a filter 48, a fourth flowmeter 49, and CH 4 Gas infrared on-line analyzer 50, CO 2 The infrared gas on-line analyzer 51, the second intermediate container 52, the twelfth valve 55, the fifth flowmeter 56, the carbon isotope analyzer 57 and the air bag 59 are sequentially connected through pipelines, wherein the carbon isotope analyzer 57 is connected with the computer 58.
In the present embodiment, a twelfth pressure gauge 53 and a fifth thermometer 54 are provided on the top of the second intermediate container 52.
In this embodiment, the pressure control device includes a hand pump 40, an eighth valve 41 and a buffer tank 42, where the hand pump 40, the eighth valve 41 and the buffer tank 42 are sequentially connected by pipelines and then divided into three branches, and the first branch connects the buffer tank 42 with a ninth valve 44 and then with the left side of the core holder 39 to control the axial pressure; the second branch is connected with the buffer tank 42 and the tenth valve 45 and then is connected with the side surface of the core holder 39, so as to control confining pressure; the third branch connects the buffer tank 42 with the eleventh valve 46 and the back pressure valve 47 to control the back pressure;
an eleventh pressure gauge 43 is provided on the top of the buffer tank 42.
A coal seam gas-bearing experimental method based on pre-pressurization and carbon fractionation techniques, comprising the steps of:
step 1: checking air tightness; after the system is connected, after equipment is cleaned, all parts of the system are inspected, inlet and outlet valves are closed, and the air tightness of the device is inspected;
step 2: testing the gas composition in the core; measuring the gas component in the core by a gas chromatograph;
step 3: loading a sample and vacuumizing; filling a rock sample into the core holder 39, opening the vacuum pump 60, the tenth valve 61, the second valve 9, the fourth valve 20, the sixth valve 31 and the twelfth valve 55, and evacuating air in the system, so that the exhaust air interferes with experimental effects, and preparing for experiments; after the vacuum is drawn, the vacuum pump 60, the tenth valve 61, the second valve 9, the fourth valve 20, the sixth valve 31, and the twelfth valve 55 are closed;
specifically, the rock sample can be particles, powder or columnar rock core, and the size of the rock core can be flexibly designed;
step 4: adding shaft pressure and confining pressure;
and (5) shaft pressing: after opening the eighth and ninth valves 41, 44, water is injected into the core holder 39 by the hand pump 40, compacting the sample in the core holder 39; after increasing the shaft pressure required for the experiment, the ninth valve 44 is closed, as required by the protocol;
and (3) confining pressure: the tenth valve 45 is opened, water is injected into the core holder 39 by the hand pump 40, and the sample in the core holder 39 is compacted; according to the requirement of the experimental scheme, after increasing the confining pressure required by the experiment, closing the tenth valve 45;
step 5: back pressure and temperature are added;
and (3) adding back pressure: according to the experimental scheme, the eleventh valve 46 is opened, and the pressure of the back pressure valve 47 is increased to the pressure required by the experiment;
heating: according to the requirement of an experimental scheme, the temperature of the temperature control box is adjusted to be required by the experiment;
step 6: saturation; according to the gas composition in the tested core, CH is added 4 、N 2 And CO 2 Pressurizing the gas to the pressure required by the experiment, and injecting the gas into the first intermediate container 34 for standby;
opening CH 4 Gas cylinder 1, first valve 2, first air compressor 4, first booster pump 5, will CH 4 The gas is pressurized to the pressure required by the experiment and stored in a first storage tank 6, and the first valve 2 is closed after the pressurization is completed;
turning on CO 2 Gas cylinder 12, third valve 13, second air compressor 15, second booster pump 16, CO 2 The gas is pressurized to the pressure required by the experiment and stored in the second storage tank 17, and the third valve 13 is closed after the pressurization is completed;
turn on N 2 The gas cylinder 23, the fifth valve 24, the third air compressor 26 and the third booster pump 27 are used for introducing CO 2 The gas is pressurized to the pressure required by the experiment and stored in the third storage tank 28, and the fifth valve 24 is closed after the pressurization is completed;
the second valve 9, the fourth valve 20 and the sixth valve 31 are opened, the gas composition in the core is injected into the first intermediate container 34, and the gas composition is monitored by the first flowmeter 11, the second flowmeter 22 and the third flowmeter 33;
after the above steps are completed, the seventh valve 37 is opened, and the prepared mixed gas is injected into the core holder 39;
step 7: experiment metering and detection;
metering: through a fourth flow meter 49, CH 4 Infrared analyzer 50, CO 2 An infrared gas analyzer 51 that meters gas flowing from the core holder 39;
and (3) detection:in the experimental process, the twelfth valve 55, the carbon isotope analyzer 57 and the computer 58 are opened, so that the delta in the core can be detected in real time 13 C 1 Values to determine free and adsorbed gas in the core;
step 8: changing the conditions and continuing to carry out a comparison experiment: according to the needs of experimental purposes, the conditions such as experimental temperature, axial pressure back pressure, gas mixing proportion, injection displacement and the like are changed according to different rock samples, and comparison experiments under other experimental conditions are developed in the same way.
Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made therein without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Claims (8)
1. Coal bed gas-bearing experimental system based on pre-pressurization and carbon fractionation technology, which comprises a core holder (39) for holding a core, characterized in that: the core holder (39) is placed in the temperature control box (38), the inlet end of the core holder (39) is connected with a gas injection device, the upper end of the core holder (39) is connected with a vacuumizing device, the outlet end of the core holder (39) is sequentially connected with a back pressure valve (47) and a gas metering analysis device, and a pressure control device is connected between the core holder (39) and the back pressure valve (47).
2. The coal seam gas bearing experiment system based on pre-pressurization and carbon fractionation technology according to claim 1, wherein: a first intermediate container (34) is connected between the gas injection device and the core holder (39), a seventh valve (37) is connected between the first intermediate container (34) and the inlet end of the core holder (39), and a tenth pressure gauge (35) and a fourth thermometer (36) are arranged at the top end of the first intermediate container (34).
3. The coal seam gas bearing experiment system based on pre-pressurization and carbon fractionation technology according to claim 2, wherein: the gas injection device comprises three branches, wherein,
the first branch is provided with a first gas bottle (1) filled with hydrocarbon gas, the outlet end of the first gas bottle (1) is sequentially connected with a first valve (2), a first pressure gauge (3), a first booster pump (5), a first storage tank (6), a second valve (9), a third pressure gauge (10) and a first flowmeter (11) through pipelines, the first booster pump (5) is further connected with a first air compressor (4), and the top of the first storage tank (6) is connected with a second pressure gauge (7) and a first thermometer (8);
the second branch is provided with N charges 2 The outlet end of the second gas cylinder (12) is sequentially connected with a third valve (13), a fourth pressure gauge (14), a second booster pump (16), a second storage tank (17), a fourth valve (20), a sixth pressure gauge (21) and a second flowmeter (22) through pipelines, the second booster pump (16) is further connected with a second air compressor (15), and the top of the second storage tank (17) is connected with a fifth pressure gauge (18) and a second thermometer (19);
the third branch is provided with CO filling 2 The third gas cylinder (23), the exit end of third gas cylinder (23) adopts the pipeline to connect gradually fifth valve (24), seventh manometer (25), third booster pump (27), third storage tank (28), sixth valve (31), ninth manometer (32) and third flowmeter (33), third booster pump (27) still are connected with third air compressor machine (26), the top of third storage tank (28) is connected with eighth manometer (29) and third thermometer (30).
4. The coal seam gas bearing experiment system based on pre-pressurization and carbon fractionation technology according to claim 1, wherein: the vacuum pumping device comprises a tenth third valve (61) and a vacuum pump (60), and the vacuum pump (60) and the thirteenth valve (61) are sequentially arranged on a pipeline at the upper end of the core holder (39) from bottom to top.
5. The coal seam gas bearing experiment system based on pre-pressurization and carbon fractionation technology according to claim 1, wherein: the gas metering analysis device comprises a filter (48), a fourth flowmeter (49) and CH 4 Gas redExternal on-line analyzer (50) and CO 2 The infrared gas on-line analyzer (51), the second intermediate container (52), the twelfth valve (55), the fifth flowmeter (56), the carbon isotope analyzer (57) and the air bag (59) are sequentially connected through pipelines to form the infrared gas on-line analyzer, wherein the carbon isotope analyzer (57) is connected with a computer (58).
6. The coal seam gas bearing experiment system based on pre-pressurization and carbon fractionation techniques of claim 5, wherein: a twelfth pressure gauge (53) and a fifth thermometer (54) are arranged on the top of the second intermediate container (52).
7. The coal seam gas bearing experiment system based on pre-pressurization and carbon fractionation technology according to claim 1, wherein: the pressure control device comprises a hand pump (40), an eighth valve (41) and a buffer tank (42), wherein the hand pump (40), the eighth valve (41) and the buffer tank (42) are sequentially connected through pipelines and then are divided into three branches, the first branch is connected with the buffer tank (42) and a ninth valve (44) and then is connected with the left side of a core holder (39), and the axial pressure is controlled; the second branch is connected with the buffer tank (42) and the tenth valve (45) and then is connected with the side surface of the core holder (39), and confining pressure is controlled; the third branch is used for connecting the buffer tank (42) with an eleventh valve (46) and a back pressure valve (47) to control back pressure;
an eleventh pressure gauge (43) is arranged at the top of the buffer tank (42).
8. A coal bed gas-bearing experimental method based on pre-pressurization and carbon fractionation technology, which is characterized by comprising the following steps:
step 1: checking air tightness; after the system is connected, after equipment is cleaned, all parts of the system are inspected, inlet and outlet valves are closed, and the air tightness of the device is inspected;
step 2: testing the gas composition in the core; measuring the gas component in the core by a gas chromatograph;
step 3: loading a sample and vacuumizing; filling a rock sample into a core holder (39), opening a vacuum pump (60), a thirteenth valve (61), a second valve (9), a fourth valve (20), a sixth valve (31) and a twelfth valve (55), and evacuating air in the system, so that the exhaust air interferes with experimental effects, and preparing for experiments; after vacuumizing, closing a vacuum pump (60), a thirteenth valve (61), a second valve (9), a fourth valve (20), a sixth valve (31) and a twelfth valve (55);
step 4: adding shaft pressure and confining pressure;
and (5) shaft pressing: after opening the eighth valve (41) and the ninth valve (44), water is injected into the core holder (39) through a hand pump (40), and a sample in the core holder (39) is compacted; according to the requirement of the experimental scheme, after the axial pressure required by the experiment is increased, the ninth valve (44) is closed;
and (3) confining pressure: opening a tenth valve (45), injecting water into the core holder (39) through a hand pump (40), and compacting the sample in the core holder (39); according to the requirement of an experimental scheme, after increasing the confining pressure required by the experiment, closing a tenth valve (45);
step 5: back pressure and temperature are added;
and (3) adding back pressure: opening an eleventh valve (46) according to the requirement of an experiment scheme, and increasing the pressure of a back pressure valve (47) to the pressure required by the experiment;
heating: according to the requirement of an experimental scheme, the temperature of the temperature control box is adjusted to be required by the experiment;
step 6: saturation; according to the gas composition in the tested core, CH is added 4 、N 2 And CO 2 Pressurizing the gas to the pressure required by the experiment, and injecting the gas into a first intermediate container (34) for standby;
opening CH 4 Gas cylinder (1), first valve (2), first air compressor (4), first booster pump (5), will CH 4 The gas is pressurized to the pressure required by the experiment and stored in a first storage tank (6), and the first valve (2) is closed after the pressurization is completed;
turning on CO 2 A gas cylinder (12), a third valve (13), a second air compressor (15) and a second booster pump (16) for introducing CO 2 The gas is pressurized to the pressure required by the experiment and stored in a second storage tank (17), and after the pressurization is finished, a third valve (13) is closed;
turn on N 2 A gas cylinder (23), a fifth valve (24), a third air compressor (26) and a third booster pump (27) for introducing CO 2 Gas and its preparation methodPressurizing until the pressure required by the experiment is stored in a third storage tank (28), and closing a fifth valve (24) after the pressurization is completed;
opening a second valve (9), a fourth valve (20) and a sixth valve (31), injecting the gas components into a first intermediate container (34) according to the gas components in the rock core, and monitoring the gas components by a first flowmeter (11), a second flowmeter (22) and a third flowmeter (33);
after the above steps are completed, a seventh valve (37) is opened, and the prepared mixed gas is injected into the core holder (39);
step 7: experiment metering and detection;
metering: through a fourth flowmeter (49), CH 4 Infrared analyzer (50) and CO 2 An infrared gas analyzer (51) for measuring the gas flowing from the core holder (39);
and (3) detection: in the experimental process, the twelfth valve (55), the carbon isotope analyzer (57) and the computer (58) are opened, so that the delta in the core can be detected in real time 13 C 1 Values to determine free and adsorbed gas in the core;
step 8: changing the conditions and continuing to carry out a comparison experiment: according to the needs of experimental purposes, the conditions such as experimental temperature, axial pressure back pressure, gas mixing proportion, injection displacement and the like are changed according to different rock samples, and comparison experiments under other experimental conditions are developed in the same way.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117740608A (en) * | 2023-12-20 | 2024-03-22 | 中国矿业大学(北京) | Experimental system and method for multi-layer combined production test by utilizing carbon fractionation |
| CN118330107A (en) * | 2024-06-13 | 2024-07-12 | 中国矿业大学(北京) | Carbon isotope-based method and system for evaluating carbon dioxide occurrence state in coal |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117740608A (en) * | 2023-12-20 | 2024-03-22 | 中国矿业大学(北京) | Experimental system and method for multi-layer combined production test by utilizing carbon fractionation |
| CN118330107A (en) * | 2024-06-13 | 2024-07-12 | 中国矿业大学(北京) | Carbon isotope-based method and system for evaluating carbon dioxide occurrence state in coal |
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