Experimental Study on CO2 Replacement CH4 Enhanced Coalbed Methane Extraction——Taking Coalbed Methane in Hancheng Mining Area as an Example
Coalbed methane reservoirs generally have low permeability,strong adsorption,and almost no natural production capacity,currently,the main production increase technology is to use fracturing to build a complex artificial fracture network and increase production channels.Supercritical CO2 has the characteristics of low viscosity,high diffusion,and low surface tension,which can be applied in hydraulic fracturing to increase recovery efficiency.In order to study the displacement ability of CO2 on CH4 under different temperature-pressure and phase state conditions in coal samples,and evaluate the role of supercritical CO2 fracturing in enhancing the efficient development of coalbed methane,this paper takes coalbed methane in the Hancheng Mining Area as an example to carry out evaluation of the pore structure characteristics of coal samples and isothermal adsorption tests.The results show that compared to CH4,CO2 has stronger adsorption capacity on the surface of coal samples,and CO2 has competitive displacement ability,which can be used to enhance the efficient development of coalbed methane;the adsorption capacity of CO2 in coal samples increases with the increase of pressure,and when it reaches high pressure,the increase tends to be gentle and shows a maximum value;the CO2 adsorption capacity significantly decreases with increasing temperature.
coalbed methaneisothermal adsorptioncompetitive replacementtemperature-pressurephase state
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