Application of Adsorption Potential Theory to Study on Adsorption-Desorption of Coal Bed Methane

Taking the Jincheng anthracite coal as the study object, the methane and nitrogen adsorption and desorption experiments were conducted at 30 °C. Base d on the uniqueness of adsorption characteristic curve, according to the adsorption and desorption data of 30。C, with the adsorption potential theory as the basis, the methane isothermal adsorption curve at 50。C was predicted.The results showed that the predicted curve and the site measured curve could be well fitted, the average absolute error of the predicted vaule was 0.5 cm3/g and the average relative error was 3.12% .Meanwhile according to the adsorption feature curves of nitrogen and met hane at 30。C, there would be a cross point at the corresponding pressure of 0.61 MPa between the nitrogen and methane adsorption characteristic curves.Thus when t he pressure was lower than 0.61 MPa, the adsorption potential of nitrogen would be higher than the adsorption potential of the methane.The nitrogen injection would pl ay a promotion role to improve the production of the coal bed methane.Therefore, a preliminary theoretical basis could be provided to determine the nitrogen injection p ressure range during the N2-ECBM process of the coal reservoir.