In order to study the effect of conventional drilling gas extraction technology, combined with the observation results of upward drilling and downlink drilling field test in 81309 working face of Baode Mine. The analysis of field test data shows that under the same gas control effect, the average gas concentration and gas purity of uplink drilling are higher than that of downlink boreholes. In the extraction range, the average pumping concentration of uplink boreholes is 1.134 times higher than that of downlink boreholes, while the average pure gas flow rate of uplink boreholes is 1.296 times higher than that of downlink boreholes. The test results show that the uplink conventional drill Hole has better pumping concentration stability and extraction effect than downlink conventional drilling.
In order to further
clarify the transport mechanism of coalbed
methane and to study the gas diffusion law in coal, this paper conducted
an experimental study on the desorption law of coal particle gas.
On the basis of experiment, the time-varying characteristics of the
diffusion coefficient in the process of coal particle gas desorption
were analyzed, and the gas diffusion calculation model considering
the time-varying diffusion coefficient was obtained by experimental
fitting. On this basis, the influence of coal particles with different
shapes on the gas desorption law is studied, and the gas diffusion
equations of flat and cylindrical coal particles based on time-varying
diffusion coefficients are established. The corresponding analytical
solutions are obtained by using mathematical and physical methods,
and the results are verified. The results show that the larger the
adsorption equilibrium pressure is, the larger the gas desorption
capacity is. At the initial stage of desorption, the larger the particle
size is, the smaller the desorption capacity and desorption speed
are. However, after reaching the “limit particle size”,
the particle size has little influence on the desorption capacity
and desorption speed. Under different temperature conditions, the
gas desorption amount monotonously increases with time. The higher
the temperature is, the greater the desorption amount is. The adsorption
constant a value slightly increases with the increase
of temperature and then decreases. The adsorption constant b value has a trend of decreasing with the increase of temperature.
The research results have very important practical significance for
the optimization of the testing method of underground coalbed methane
content and the prediction of coal and gas outburst risk.
The No.15 coal seam of Sijiazhuang Coal Mine belongs to high gas and low permeability coal seam. Hydraulic fracturing, as a technical measure for outburst prevention, is more and more widely used in high gas outburst mines. The influence of hydraulic fracturing high-pressure water on stress and displacement of roadway is analyzed, and the feasibility of hydraulic fracturing is verified. The industrial test of hydraulic fracturing through layers was carried out and the effect of gas extraction was investigated. The average concentration and pure volume of gas extraction unit in the fracturing area were 3.1 times and 5.7 times of those in the non fracturing area, respectively, which verified the permeability increasing effect of hydraulic fracturing measures. Through fracturing test, the extraction effect has been significantly improved. This paper provides important theoretical support and practical basis for hydraulic fracturing under similar conditions.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.