CN114062517B - Mixed gas adsorption testing device and method for shale gas and coalbed gas - Google Patents
Mixed gas adsorption testing device and method for shale gas and coalbed gas Download PDFInfo
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Abstract
The invention discloses a mixed gas adsorption testing device for shale gas and coal bed gas, wherein the upstream end of a high-precision metering pump is connected with an air inlet pipeline and a vacuumizing pipeline, the air inlet pipeline is provided with an air inlet valve, the vacuumizing pipeline is provided with a vacuumizing valve, the downstream end of the high-precision metering pump is connected with an air outlet pipeline, the air outlet pipeline is provided with a first hose and a second hose which are respectively connected with a reference cylinder and a sample cylinder, the air outlet pipeline is also provided with an air outlet valve and an air outlet valve, a sampling pipeline connected with a chromatograph is arranged on the air outlet pipeline between the air outlet valve and the air outlet valve, the sampling pipeline is provided with a sampling valve, the reference cylinder and the sample cylinder are respectively arranged on two high-precision weighing devices, the temperature and pressure measuring device comprises a first temperature and pressure measuring device and a second temperature and pressure measuring device, and the temperature control system is used for controlling the temperature of the whole device. The invention can measure and calculate the total adsorption quantity of the mixed gas in shale and coal and the adsorption component of each component, and the calculation result is accurate.
Description
Technical Field
The invention relates to the technical field of petroleum and natural gas exploration and development, in particular to a device and a method for testing the adsorption of mixed gas of shale gas and coalbed gas.
Background
Shale gas and coal bed gas are used as important unconventional natural gas resources in China, the resource quantity is huge, and the shale gas and the coal bed gas occupy an increasingly important proportion in natural gas production in China. Meanwhile, shale and coal beds are also important reservoirs for carbon dioxide sequestration, and have important significance for achieving a 'two-carbon' strategic target. Although the main components of shale gas and coal bed gas are both methane, some other gases, such as hydrocarbon gases like carbon dioxide, nitrogen and ethane, are still enriched. Carbon dioxide sequestration is also the injection of large amounts of carbon dioxide into the gas such as methane already in the reservoir, and the main occurrence of these gases in shale and coal seams is the adsorption state. The research on the characteristics of the adsorption-state mixed gas has important significance for the production of shale gas and coalbed gas and the sequestration of carbon dioxide. Therefore, it is necessary to measure the adsorption amount of these gases in shale and coal beds in a mixed state by a laboratory.
The existing method for testing the adsorption quantity of single-component gas in shale or coal seam mainly comprises a gravity method, a volume method, a pressure method and the like. However, the adsorption of the mixed gas requires simultaneous measurement of the total amount of adsorption and the adsorption components of each component, and it is necessary to measure the components of the mixed gas in a free state at the sample end and also to be able to precisely meter the components of each component of the injected mixed gas, and therefore, the mixed gas adsorption apparatus needs to inject the mixed gas using a high-precision metering pump. In the calculation process, the mixed gas state equation is required to be used for calculating the density of the mixed gas, and the errors of the existing mixed gas state equation are large, so that the calculation of the adsorption components of each component causes large errors, and the calculation result cannot be used.
Disclosure of Invention
The invention aims to provide a device and a method for testing the adsorption of mixed gas of shale gas and coal bed gas, which are used for solving the problems in the prior art, and the device and the method can be used for measuring and calculating the total adsorption quantity of the mixed gas in the shale and the coal and the adsorption component of each component, and are accurate in calculation result without using a mixed gas state equation.
In order to achieve the above object, the present invention provides the following solutions:
the invention provides a mixed gas adsorption testing device for shale gas and coalbed methane, which comprises a high-precision metering pump, a sample cylinder, a reference cylinder, a high-precision weighing device, a chromatograph, a temperature and pressure measuring device and a temperature control system, wherein the upstream end of the high-precision metering pump is connected with a gas source of the mixed gas through a gas inlet pipeline and is connected with the vacuumizing device through a vacuumizing pipeline, a gas inlet valve is arranged on the gas inlet pipeline, a vacuumizing valve is arranged on the vacuumizing pipeline, the downstream end of the high-precision metering pump is connected with a gas outlet pipeline, a first hose and a second hose which are respectively connected with the reference cylinder and the sample cylinder are arranged on the gas outlet pipeline, a gas outlet valve is arranged on the gas outlet pipeline which is arranged on the upstream of the reference cylinder and the sample cylinder, the gas outlet pipeline which is arranged on the downstream of the reference cylinder and the sample cylinder is connected with the vacuumizing device, a sampling pipeline which is connected with the chromatograph is arranged on the gas outlet pipeline between the gas outlet valve and the gas outlet pipeline, the sampling pipeline is provided with a sampling valve, and the reference cylinder and the sample cylinder and the gas outlet valve are respectively arranged on the gas outlet pipeline which are respectively arranged on the temperature and pressure measuring device and the temperature and pressure measuring device which can be used for measuring the temperature and the temperature of the temperature and pressure measuring device in the high-precision measuring device.
Preferably, the high-precision weighing device is a high-precision electronic scale.
Preferably, the first temperature and pressure measuring device and the second temperature and pressure measuring device are both temperature and pressure gauges.
Preferably, the first hose and the second hose are both high pressure hoses.
Preferably, the sampling valve is a six-way valve.
Preferably, the precision of the high precision metering pump is 0.001 milliliter.
Preferably, the precision of the high-precision electronic scale is not less than 0.001 g.
The invention also provides a shale gas and coal bed gas mixed gas adsorption test method based on the shale gas and coal bed gas mixed gas adsorption test device, which comprises the following steps:
s1: injecting mixed gas into the high-precision metering pump, wherein the mole fraction of each component is measured by a gas chromatograph or provided by a configuration party, and injecting the mixed gas into the reference cylinder until reaching a target pressure P p After the temperature and the pressure are stable, measuring the mass change of the reference cylinder before and after the air filling by the high-precision weighing device, wherein the mass density of the mixed gas is as follows:
the molar density of each component can be obtained by the molecular weight and the mole fraction of each component:
in the formulas (1) - (2):
Δm: the mass change of the reference cylinder before and after the air filling,
V r : with reference to the in-cylinder volume,
M i : the molecular weight of each component is determined by the weight of the component,
Z i : mole fractions of the components;
s2: loading a sample into the sample cylinder, wherein the total volume of the sample cylinder is V c The mass of the loaded sample is m s The true density of the sample is ρ s The void volume of the sample cylinder was obtained as:
s3: controlling the pressure in the high-precision metering pump to be P p After the reference cylinder and the sample cylinder are vacuumized, injecting a part of mixed gas into the reference cylinder and the sample cylinder from the high-precision metering pump, closing the gas outlet valve, and recording the pressure in the sample cylinder as P after the adsorption reaches balance 1 Recording the change of mass of the reference cylinder as delta m 1 Recording the volume change of the high-precision metering pump to be delta V 1 Sampling by the sampling valve, and measuring the mole fraction of each component to be y by using the chromatograph 1i Calculating the mass density of the mixed gas in the reference cylinder:
the molar density is as follows:
calculation at P 1 The adsorption components of the following components are as follows:
n 1i ＝ρ M ΔV 1 Z i －ρ M1 V void y 1i (6)，
the total adsorption amount is as follows:
n 1 ＝Σn 1i (7)；
s4: from the high precisionContinuously injecting a part of mixed gas into the reference cylinder and the sample cylinder after vacuumizing in the metering pump, closing the air outlet valve, and recording the pressure in the sample cylinder as P after the adsorption reaches balance J Recording the change of mass of the reference cylinder as delta m J Recording the volume change of the high-precision metering pump to be delta V J Sampling by the sampling valve, and measuring the mole fraction of each component to be y by using the chromatograph Ji Calculating the mass density of the mixed gas in the reference cylinder:
the molar density is as follows:
calculation at P J The adsorption components of the following components are as follows:
n Ji ＝ρ M ΔV J Z i －ρ MJ V void y Ji (10)，
the total adsorption amount is as follows:
n J ＝Σn Ji (11)。
preferably, the calculated total adsorption amount and the adsorption amount of each component are converted into absolute total adsorption amount
Absolute adsorption component of each component>
The mole fraction of each component adsorption state is obtained:
compared with the prior art, the invention has the following technical effects:
according to the mixed gas adsorption test device and method for shale gas and coalbed gas, the total injection amount and the component amounts are respectively measured through the high-precision metering pump, the density of the mixed gas in the reference cylinder is directly measured through a gravity method, and the components of the gas are measured through the chromatograph, so that the adsorption total amount of the mixed gas and the adsorption component of each component are obtained through calculation, a mixed gas state equation is not needed, errors caused by the use of the mixed gas state equation are avoided, and accuracy of a calculation result is guaranteed.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic structural diagram of a mixed gas adsorption test device for shale gas and coal bed gas provided by the invention;
FIG. 2 is a graph of adsorption of carbon dioxide and methane mixture as a function of pressure in an embodiment of the invention;
FIG. 3 is a graph showing the relationship between the mole fraction of free gas and the mole fraction of adsorbed gas in the embodiment of the invention;
in the figure: 100-shale gas and coalbed gas mixed gas adsorption testing device, 1-high precision metering pump, 2-sample cylinder, 3-reference cylinder, 4-high precision weighing device, 5-chromatograph, 6-air inlet pipeline, 7-vacuumizing pipeline, 8-air inlet valve, 9-vacuumizing valve, 10-air outlet pipeline, 11-first hose, 12-second hose, 13-air outlet valve, 14-air outlet valve, 15-sampling pipeline, 16-sampling valve, 17-first temperature and pressure measuring device and 18-second temperature and pressure measuring device.
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.
The invention aims to provide a mixed gas adsorption test device and method for shale gas and coal bed gas, which are used for solving the problems in the prior art, measuring and calculating the total adsorption quantity of the mixed gas in shale and coal and the adsorption components of each component, and the calculation result is accurate without using a mixed gas state equation.
In order that the above-recited objects, features and advantages of the present invention will become more readily apparent, a more particular description of the invention will be rendered by reference to the appended drawings and appended detailed description.
As shown in fig. 1, the embodiment provides a mixed gas adsorption test device 100 for shale gas and coalbed methane, which comprises a high-precision metering pump 1, a sample cylinder 2, a reference cylinder 3, a high-precision weighing device 4, a chromatograph 5, a temperature and pressure measuring device and a temperature control system, wherein the upstream end of the high-precision metering pump 1 is connected with a gas source of the mixed gas through a gas inlet pipeline 6 and is connected with the vacuum pumping device through a vacuum pumping pipeline 7, the gas inlet pipeline 6 is provided with a gas inlet valve 8, the vacuum pumping pipeline 7 is provided with a vacuum pumping valve 9, the downstream end of the high-precision metering pump 1 is connected with a gas outlet pipeline 10, the gas outlet pipeline 10 is provided with a first hose 11 and a second hose 12 which are respectively connected with the reference cylinder 3 and the sample cylinder 2, the gas outlet pipeline 10 at the upstream of the reference cylinder 3 and the sample cylinder 2 is provided with a gas outlet valve 13, the exhaust valve 14 is arranged on the exhaust pipeline 10 at the downstream of the reference cylinder 3 and the sample cylinder 2, the downstream end of the exhaust valve 14 is connected with the vacuumizing device, the sampling pipeline 15 connected with the chromatograph 5 is arranged on the exhaust pipeline 10 between the exhaust valve 13 and the exhaust valve 14, the sampling pipeline 15 is provided with the sampling valve 16, the reference cylinder 3 and the sample cylinder 2 are respectively arranged on the two high-precision weighing devices 4, the temperature and pressure measuring devices comprise a first temperature and pressure measuring device 17 capable of measuring the temperature and pressure of the gas in the high-precision metering pump 1 and a second temperature and pressure measuring device 18 capable of measuring the temperature and pressure of the gas in the reference cylinder 3 and the sample cylinder 2, and the temperature control system is used for controlling the temperature of the whole device.
In this embodiment, the high-precision metering pump 1 is used as an injection component of the mixed gas, and can precisely meter the volume of the injected gas in a constant pressure state, and calculate the components of each component of the injected gas while calculating the total amount of the injected gas through the density and the components of the mixed gas, wherein the upstream end of the high-precision metering pump is connected with a gas source of the mixed gas, and the downstream end is connected with a sample end; the sample cylinder 2 is used for arranging shale or coal samples, is connected with the high-precision metering pump 1 and the reference cylinder 3 through a pipe valve, can be emptied and vacuumized through the pipe valve, the total volume of the sample cylinder 2 and a pipeline connected with the sample cylinder needs to be accurately calibrated, and the whole sample cylinder 2 is arranged on the high-precision weighing device 4 to accurately meter the change of mass; the reference cylinder 3 is connected with the high-precision metering pump 1 and the sample cylinder 2 through a pipe valve, and can be emptied and vacuumized through the pipe valve, the total volume of the reference cylinder 3 and a pipeline connected with the reference cylinder needs to be accurately calibrated, and the whole reference cylinder 3 is arranged on the high-precision weighing device 4 to accurately meter the change of mass; the high-precision weighing device 4 is used for individually weighing the mass changes of the reference cylinder 3 and the sample cylinder 2; the chromatograph 5 is connected with the pipeline communicated with the sample cylinder 2 and the reference cylinder 3 through a sampling pipeline 15, and mixed gas is sent into the chromatograph 5 through carrier gas after sampling for quantitative analysis of the proportion of gas components. The device respectively measures the total injection amount and the component amount through the high-precision metering pump 1, directly measures the density of the mixed gas in the reference cylinder 3 through a gravity method, and measures the components of the gas through the chromatograph 5, so that the adsorption total amount of the mixed gas and the adsorption component of each component are calculated and obtained, a mixed gas state equation is not required, the error caused by using the mixed gas state equation is avoided, and the accuracy of a calculation result is ensured.
In this embodiment, the high-precision weighing device 4 is a high-precision electronic scale, and is convenient to use.
In this embodiment, the first temperature and pressure measuring device 17 and the second temperature and pressure measuring device 18 are temperature and pressure gauges, and can measure the temperature and pressure of the gas in the high-precision metering pump 1 by connecting one temperature and pressure gauge to the gas outlet pipeline 10 between the high-precision metering pump 1 and the gas outlet valve 13, and can measure the temperature and pressure of the gas in the reference cylinder 3 and the sample cylinder 2 by connecting the other temperature and pressure gauge to the gas outlet pipeline 10 between the gas outlet valve 13 and the gas outlet valve 14.
In this embodiment, the first hose 11 and the second hose 12 are both high-pressure hoses capable of withstanding high pressure so as to perform measurement under high pressure conditions.
In this embodiment, the sampling valve 16 is a six-way valve, and can sample and then send the mixed gas into the chromatograph 5 by the carrier gas for quantitative analysis of the gas component ratio.
In the embodiment, the precision of the high-precision metering pump 1 is 0.001 milliliter, so that the measurement precision is ensured, and the accuracy of a calculation result is improved.
In the embodiment, the precision of the high-precision electronic scale is not lower than 0.001 g, so that the measurement precision is ensured, and the accuracy of a calculation result is improved.
The mixed gas adsorption test method of shale gas and coal bed gas based on the mixed gas adsorption test device of shale gas and coal bed gas comprises the following steps:
s1: the mixed gas is injected into a high-precision metering pump 1, the mole fractions of the components are measured by a gas chromatograph or provided by a configuration party, and the mixed gas is injected into a reference cylinder 3 until a target pressure P is reached p After the temperature and the pressure are stable, the mass change of the reference cylinder 3 before and after the air filling is measured by the high-precision weighing device 4, and the mass density of the mixed gas is as follows:
the molar density of each component can be obtained by the molecular weight and the mole fraction of each component:
in the formulas (1) - (2):
Δm: the mass change of the reference cylinder before and after the air filling,
V r : with reference to the in-cylinder volume,
M i : the molecular weight of each component is determined by the weight of the component,
Z i : mole fractions of the components;
s2: sample is filled into a sample cylinder 2, and the total volume of the sample cylinder 2 is V c The mass of the loaded sample is m s The true density of the sample is ρ s The void volume of the sample cylinder 2 was obtained as:
s3: controlling the pressure in the high-precision metering pump 1 at P p After the reference cylinder 3 and the sample cylinder 2 are vacuumized, part of mixed gas is injected into the reference cylinder 3 and the sample cylinder 2 from the high-precision metering pump 1, the gas outlet valve 13 is closed, and after the adsorption reaches equilibrium, the pressure in the sample cylinder 2 is recorded as P 1 The change in mass of the reference cylinder 3 was recorded as Δm 1 Recording the volume change of the high-precision metering pump 1 as DeltaV 1 The sample was taken by the sampling valve 16, and the mole fraction of each component was measured as y by the chromatograph 5 1i The mass density of the mixed gas in the reference cylinder 3 is calculated:
the molar density is as follows:
calculation at P 1 The adsorption components of the following components are as follows:
n 1i ＝ρ M ΔV 1 Z i －ρ M1 V void y 1i (6)，
the total adsorption amount is as follows:
n 1 ＝Σn 1i (7)；
s4: after a part of the mixed gas is continuously injected from the high-precision metering pump 1 to the vacuumizing processThe reference cylinder 3 and the sample cylinder 2 are internally provided with a gas outlet valve 13 which is closed, and after the adsorption reaches the balance, the pressure in the sample cylinder 2 is recorded as P J The change in mass of the reference cylinder 3 was recorded as Δm J (the mass change is the difference between the mass change and the reference cylinder mass after vacuum pumping), the volume change of the high-precision metering pump 1 is recorded as DeltaV J (this volume change is the difference from the initial volume before the start of the experiment), and the sample was taken by the sampling valve 16, and the mole fraction of each component was measured as y by the chromatograph 5 Ji The mass density of the mixed gas in the reference cylinder 3 is calculated:
the molar density is as follows:
calculation at P J The adsorption components of the following components are as follows:
n Ji ＝ρ M ΔV J Z i －ρ MJ V void y Ji (10)，
the total adsorption amount is as follows:
n J ＝Σn Ji (11)。
such a calculation may avoid cumulative errors for each step, minimizing errors.
In this example, the calculated total adsorption amount and adsorption amount of each component are converted into absolute total adsorption amount
Absolute adsorption component of each component>
The mole fraction of each component adsorption state is obtained:
the calculation described above yields the total adsorption amount and the excess adsorption amount of the adsorption component of each component (Gibbs Excess adsorption), which amounts need to be converted into absolute adsorption amounts (Absolute adsorption), which are specific methods already in the literature and are not included in the present disclosure and are therefore not described in the present disclosure. After the absolute total adsorbed amount and the absolute adsorbed component of each component are obtained, a graph of the absolute adsorbed component against pressure can be drawn as shown in fig. 2. In addition, as shown in FIG. 3, the free form component y can also be plotted Ji And adsorbed state component x Ji To analyze the competitive adsorption relationship of the components.
Specifically, the procedure for testing using carbon dioxide and methane bi-component gas and powdered shale samples was as follows:
1. preparation of a gas mixture and measurement of the Density
All valves of the system are closed, the vacuumizing valve 9 is opened, and the high-precision metering pump 1 is vacuumized for 10 minutes and then closed. The volume of the high-precision metering pump 1 is increased to the maximum, and then the air inlet valve 8 is opened to inject carbon dioxide gas with certain pressure and then is closed, for example, 6MPa; after the gas source is switched, the gas inlet valve 8 is opened, and methane gas with a certain pressure is injected, and then the gas inlet valve is closed, for example, 20MPa. The high-precision metering pump 1 is advanced and retracted a plurality of times to uniformly mix the gas, for example, 5 times. The gas outlet valve 13 is opened to inject part of the mixed gas into the reference cylinder 3, after the system is stabilized, the mass change of the reference cylinder 3 is recorded, and the mass density is calculated using formula (1). A small amount of sample is taken through the sampling valve 16, and the mole fractions of the carbon dioxide and methane which are originally injected into the high-precision metering pump 1 are determined by a chromatographic analyzer
And->
The molar density was calculated by formula (2), wherein the molecular weight of carbon dioxide was 44.01 and the molecular weight of methane was 16.04. At this time, the pressure of the reference cylinder 3 is recorded as P 0 The high-precision metering pump 1 is pressedThe force is also set to P 0 And a constant pressure control mode is used, in which the volume of the high-precision metering pump 1 is recorded as V 0 。
The exhaust valve 14 is opened to evacuate the gas from the reference cylinder 3 and the sample cylinder 2.
2. Sample preparation, installation and initialization
Pulverizing shale sample, sieving to 40-60 mesh, drying according to experimental standard, and loading into sample cylinder 2. After closing all valves, the exhaust valve 14 is opened and the reference cylinder 3 and sample cylinder 2 are evacuated. After the evacuation is completed, all valves are closed, and the system temperature is waited to rise to the target temperature, for example 40 ℃.
3. First adsorption Point test
The air outlet valve 13 connected between the high-precision metering pump 1 and the sample cylinder 2 and between the reference cylinder 3 is opened, and the air outlet valve 13 is immediately closed when the pressure of the reference cylinder 3 and the sample cylinder 2 reaches about 1 MPa. The air outlet valve 13 may be an automatic control valve or a manual valve. The pressure change condition in the sample cylinder 2 is monitored, and the shale adsorption gas mixture is considered to be completed after the pressure is not continuously reduced and is kept stable. At this time, the recording pressure was P 1 The pressure P is obtained by taking a small amount of gas sample through the sampling valve 16 and performing component analysis 1 Mole fraction y of carbon dioxide and methane at the lower sample cylinder end 1i The volume change of the high-precision metering pump 1 was recorded, the mass change of the reference cylinder 3 was recorded, and the total adsorption amount at the first pressure point and the adsorption components of the respective components were calculated by the formulas (4) - (7).
4. Subsequent adsorption site testing
The gas outlet valve 13 connecting the high-precision metering pump 1 and the sample cylinder 2 and the reference cylinder 3 is opened, and the gas outlet valve 13 is closed immediately after the pressures of the reference cylinder 3 and the sample cylinder 2 reach the target pressure (for example, the second pressure point is 2MPa and the third pressure point is 3 MPa). The pressure change condition in the sample cylinder 2 is monitored, and the shale adsorption gas mixture is considered to be completed after the pressure is not continuously reduced and is kept stable. At this time, the pressure at the J-th adsorption point is P J The pressure P is obtained by taking a small amount of gas sample through the sampling valve 16 and performing component analysis J Mole fraction y of carbon dioxide and methane at the lower sample cylinder end Ji Recording high precision meteringThe change in volume of the pump 1, the change in mass of the reference cylinder 3 was recorded, and the total adsorbed amount at the J-th pressure point and the adsorbed component of each component were calculated by using the formula (8) -the formula (11).
5. Calculation of absolute adsorption quantity and drawing of experimental curve
All the above obtained excess adsorption amounts are converted into absolute adsorption amounts by conversion formulas of excess adsorption amounts and absolute adsorption amounts in the literature. The mole fraction of each adsorption state was calculated by formula (12). As shown in fig. 2, a graph of absolute total adsorption amount and absolute adsorption component of each component as a function of pressure was drawn, as shown in fig. 3, a phase diagram was drawn with adsorbed and free components, and the adsorption results were analyzed.
The traditional method adopts a multi-component gas state equation for calculation, the error of the multi-component gas state equation increases with the increase of the component number, and the error of the calculation result is large. The invention has the advantages that the density of the bi-component or multi-component gas is directly measured, a multi-component gas state equation is not needed, and the error caused by using a mixed gas state equation is avoided, thereby ensuring the accuracy of the calculation result.
The principles and embodiments of the present invention have been described in detail with reference to specific examples, which are provided to facilitate understanding of the method and core ideas of the present invention; also, it is within the scope of the present invention to be modified by those of ordinary skill in the art in light of the present teachings. In view of the foregoing, this description should not be construed as limiting the invention.
Claims (9)
1. A mixed gas adsorption testing device for shale gas and coal bed gas is characterized in that: the high-precision measuring device comprises a high-precision measuring pump, a sample cylinder, a reference cylinder, a high-precision weighing device, a chromatograph, a temperature and pressure measuring device and a temperature control system, wherein the upstream end of the high-precision measuring pump is connected with a gas source of mixed gas through a gas inlet pipeline and connected with the vacuum pumping device through a vacuum pumping pipeline, a gas inlet valve is arranged on the gas inlet pipeline, a vacuum pumping valve is arranged on the vacuum pumping pipeline, the downstream end of the high-precision measuring pump is connected with a gas outlet pipeline, a first hose and a second hose which are respectively connected with the reference cylinder and the sample cylinder are arranged on the gas outlet pipeline, a gas outlet valve is arranged on the gas outlet pipeline at the upstream of the reference cylinder, the reference cylinder and the temperature and pressure measuring device are arranged on the gas outlet pipeline at the downstream of the sample cylinder, a sampling pipeline connected with the chromatograph is arranged between the gas outlet valve and the gas outlet pipeline, a sampling valve is arranged on the sampling pipeline, the reference cylinder and the sample cylinder are respectively arranged on the two high-precision measuring devices, and the temperature measuring device can be used for measuring the temperature and pressure of the temperature and pressure measuring device can be used for measuring the temperature and pressure of the temperature and pressure measuring device in the temperature and the temperature measuring device.
2. The shale gas and coal bed gas mixed gas adsorption testing device according to claim 1, wherein: the high-precision weighing device is a high-precision electronic scale.
3. The shale gas and coal bed gas mixed gas adsorption testing device according to claim 1, wherein: the first temperature and pressure measuring device and the second temperature and pressure measuring device are both temperature and pressure gauges.
4. The shale gas and coal bed gas mixed gas adsorption testing device according to claim 1, wherein: the first hose and the second hose are both high pressure hoses.
5. The shale gas and coal bed gas mixed gas adsorption testing device according to claim 1, wherein: the sampling valve is a six-way valve.
6. The shale gas and coal bed gas mixed gas adsorption testing device according to claim 1, wherein: the precision of the high-precision metering pump is 0.001 milliliter.
7. The shale gas and coal bed gas mixed gas adsorption testing device according to claim 2, wherein: the precision of the high-precision electronic scale is not lower than 0.001 g.
8. A method for testing the adsorption of a mixed gas of shale gas and coalbed gas based on the device for testing the adsorption of a mixed gas of shale gas and coalbed gas according to any one of claims 1 to 7, comprising the steps of:
s1: injecting mixed gas into the high-precision metering pump, wherein the mole fraction of each component is measured by a gas chromatograph or provided by a configuration party, and injecting the mixed gas into the reference cylinder until reaching a target pressure P p After the temperature and the pressure are stable, measuring the mass change of the reference cylinder before and after the air filling by the high-precision weighing device, wherein the mass density of the mixed gas is as follows:
the molar density of each component can be obtained by the molecular weight and the mole fraction of each component:
in the formulas (1) - (2):
Δm: the mass change of the reference cylinder before and after the air filling,
V r : with reference to the in-cylinder volume,
M i : the molecular weight of each component is determined by the weight of the component,
Z i : mole fractions of the components;
s2: loading a sample into the sample cylinder, wherein the total volume of the sample cylinder is V c The mass of the loaded sample is m s The true density of the sample is ρ s The void volume of the sample cylinder was obtained as:
s3: controlling the pressure in the high-precision metering pump to be P p After the reference cylinder and the sample cylinder are vacuumized, injecting a part of mixed gas into the reference cylinder and the sample cylinder from the high-precision metering pump, closing the gas outlet valve, and recording the pressure in the sample cylinder as P after the adsorption reaches balance 1 Recording the change of mass of the reference cylinder as delta m 1 Recording the volume change of the high-precision metering pump to be delta V 1 Sampling by the sampling valve, and measuring the mole fraction of each component to be y by using the chromatograph 1i Calculating the mass density of the mixed gas in the reference cylinder:
the molar density is as follows:
calculation at P 1 The adsorption components of the following components are as follows:
n 1i ＝ρ M ΔV 1 Z i －ρ M1 V void y 1i (6)，
the total adsorption amount is as follows:
n 1 ＝Σn 1i (7)；
s4: continuously injecting a part of mixed gas into the vacuumized reference cylinder and sample cylinder from the high-precision metering pump, closing the gas outlet valve, and recording the pressure in the sample cylinder as P after the adsorption reaches equilibrium J Recording the change of mass of the reference cylinder as delta m J Recording the high-precisionVolume change of the metering pump to DeltaV J Sampling by the sampling valve, and measuring the mole fraction of each component to be y by using the chromatograph Ji Calculating the mass density of the mixed gas in the reference cylinder:
the molar density is as follows:
calculation at P J The adsorption components of the following components are as follows:
n Ji ＝ρ M ΔV J Z i －ρ MJ V void y Ji (10)，
the total adsorption amount is as follows:
n J ＝Σn Ji (11)。
9. the method for testing the adsorption of the mixed gas of shale gas and coal bed gas according to claim 8, wherein the method comprises the following steps of: converting the calculated total adsorption amount and adsorption components of each component into absolute total adsorption amount
Absolute adsorption component of each component
The mole fraction of each component adsorption state is obtained:
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