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煤层渗透率变化是注气提高煤层气采收率过程中最为关注的问题之一,而煤的吸附膨胀是造成渗透率伤害的主控因素。系统总结了国内外有关煤吸附膨胀的研究成果,发现争议较多,认为其主要原因在于对膨胀机理的认识深度不够及研究方法不一。相对于膨胀计法和应力计法,光学法观测煤膨胀效应的精度较高,建议尽量采用大块的煤样,以增强对煤储层的代表性。在煤膨胀机理的研究中,建议重点分析煤大分子结构固有的力学性质,及CO2对煤分子结构可能造成的影响。
The change of coal seam permeability is one of the most concerned problems in the process of gas injection to improve the recovery of coalbed methane. The adsorption and expansion of coal are the main controlling factors that cause the permeability damage. The results of the research on coal adsorption and expansion at home and abroad are summarized, and many controversies are found. The main reason is that the understanding of the expansion mechanism is not deep enough and the research methods are different. Relative to the dilatometer method and the stress meter method, the optical method to observe the coal expansion effect of high accuracy, it is recommended to use large pieces of coal samples to enhance the representation of the coal reservoir. In the study of coal expansion mechanism, it is suggested to focus on the inherent mechanical properties of coal macromolecular structure and the possible effect of CO2 on coal molecular structure.