Device and method for measuring gas content

Abstract

The invention provides a device and a method for measuring gas content. The device comprises a hydrogen flame ionization detector, a digital control and data collecting unit, an desorption tank, a hydrogen source, a gas source, and a gas circuit control component, wherein the desorption tank is arranged inside a constant-temperature chamber; the gas circuit control component is used for controlling on / off of a gas circuit; the digital control and data collecting unit comprises a master control chip; the signal output end of the hydrogen flame ionization detector is connected with the signal input end of a master control chip; the control end of the gas circuit control component is connected with the control signal output end of the master control chip; the gas source is connected with a gas inlet of the desorption tank through the gas circuit control component; an exhaust port of the desorption tank is connected with the hydrogen flame ionization detector through the gas circuit control component. By adopting the device and the method, volume parameters of hydrocarbon gases resolved from a rack and the change conditions along with the time can be directly measured; the device is high in sensitivity, stable and reliable, and accurate in result; the measurement result is not interfered by dead volumes of non-hydrocarbon gases and gas in the desorption tank.

Description

technical field [0001] The invention relates to a gas content measuring device and method, belonging to the technical field of exploration and testing. Background technique [0002] The main components of coalbed methane and shale gas are hydrocarbon gases, so the accurate determination of hydrocarbon gas content in coal rock, shale and sandstone formations is the key to ensure the accuracy of the evaluation results of coalbed methane and shale gas resources. [0003] At present, there are three main types of gas content measurement devices and methods for coalbed methane and shale gas at home and abroad: direct volume measurement device, which directly measures the total volume of desorbed gas or the volume of desorbed gas in different time periods , this kind of device has a poor response to the change of desorbed gas volume over time; the volume flow measurement device obtains its total volume or the volume of different time periods by continuously measuring the volume fl...

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Problems solved by technology

[0003] At present, there are three main types of gas content measurement devices and methods for coalbed methane and shale gas at home and abroad: direct volume measurement device, which directly measures the total volume of desorbed gas or the volume of desorbed gas in different time periods , this kind of device has a poor response to the change of desorbed gas volume over time; the volume flow measurement device obtains its total volume or the volume of different time periods by continuously measuring the volume flow rate of desorbed gas, and this device can obtain the desorbed gas volume The continuous change of the gas flow rate, but the measurement error of the gas flow rate is large when the desorption rate is low, and it is easily affected by the ambient temperature and pressure; the mass flow measurement device calculates its volume flow rate by continuously measuring the mass flow rate of the desorption gas , to obtain the total volume of the desorbed gas or the volume of different time periods. This device has a strong ability to resist the influence of ambient temperature and pressure, but the measurement error of the gas flow rate is large when the desorption rate is low.

[0004] It can be seen that the existing gas content measurement devices have the following problems: First, they cannot distinguish between hydrocarbon gases and non-hydrocarbon gases in the adsorbed gas, and the measurement results are far from the requirements for accurate evaluation of natural gas reserves in coal rock, mud shale, and sandstone formations. There is a certain distance; second, the measurement sensitivity and accuracy are not high enough, especially for the measurement of shale gas content, when the gas content is low, the uncertainty of the measurement data is too high; third, the dead volume in the measurement process cannot be completely eliminated Interference of gases on measurement results

In addition, because the rock adsorbed gas is heterogeneous during the analysis process, and its chemical composition changes dynamically, therefore, for the adsorbed gas with complex composition, the measurement results of the above device are less reliable

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