煤储层临界解吸压力理论计算误差分析及影响因素研究
Study on Influencing Factors and Error Analysis of Critical Desorption Pressure in Coal

本文基于现有的临界解吸压力计算方法，对目前煤层气井在生产过程中常见到的理论计算临界解吸压力与实际排采不吻合的现象深入分析原因。分析认为，临界解吸压力计算过程中吸附解吸曲线及含气量测定结果与实际的误差及其相互之间的不匹配性是临界解吸压力计算出现误差的主要原因。对于吸附解吸曲线而言，目前的实验结果均是基于煤储层中不含液相水的前提，而实际储层富含液相水；对于含气量而言，由于煤岩发育的非均质性及连通性导致的测定含气量与实际含气量存在差异。最后基于改进的临界解吸压力理论，考虑到现场参数获得的难易程度，提出新的临界解析压力影响因素，并以实际煤层气藏为例进行分析。
Based on the existing calculation method of critical desorption pressure, the reason why the critical desorption pressure is not consistent with the actual production is analyzed. It is considered that the main reason for the errors in the calculation of the critical desorption pressure is the mismatch between the adsorption/desorption curve and the measured results of the gas content and the ac-tual values. For the adsorption/desorption curve, the current experimental results are based on the premise that there is no liquid phase water in the coal reservoir, while the actual reservoir is rich in liquid phase water; for the gas content, the measured gas content is different from the actual gas content due to the heterogeneity and connectivity of coal and rock development. Finally, based on the improved critical desorption pressure theory, considering the difficulty of obtaining field pa-rameters, a new influencing factor of critical desorption pressure is proposed and analyzed by tak-ing actual coalbed methane reservoir as an example.