Analysis on parameter sensibility during isothermal adsorption experiment of coal reservoir

Volumetric adsorption experiment is the primary method to determine the adsorption capability and gas content of coal reservoirs. Reference cylinder volume V₁, free volume V₂ in sample cylinder and pressure gauge precision were identified as the key factors influencing adsorption experiment. To understand how the parameters impact isotherm adsorption experiment results and improve the precision of the experiment, in this paper, stability analysis and accuracy analysis were performed for adsorption experiment according to Boyle's law. Based on the established models, the adsorption experiments are simulated by Matlab software. The result shows that the stability and the accuracy of experiment are controlled by V₁, V₂, pressure gauge precision and reference cylinder volume. The higher pressure gauge precision, the more stable and precise adsorption experiment is. When the pressure gauge precision is fixed, only V₁ and V₂ are smaller and satisfy certain conditions which have been simulated can the experiment achieve good stability and precision. Comparative isothermal adsorption experiment was conducted on medium rank coal from Hancheng area in the eastern Ordos basin by using the results obtained from optimization. Result indicates that the quality of adsorption results is improved, the maximum adsorption difference is 1.45 cm³/g, far less than 5.27 cm³/g from the experiment not optimized by models.