煤基质自调节效应实验

煤储层渗透率是决定煤层气开采成败的关键参数之一。以煤基质为研究对象,根据应力来源的不同,提出了煤基质内外应力的概念。分析认为:煤储层渗透率随煤层气开采而动态变化正是煤基质内外应力综合作用的结果。随着煤层气的采动,有效应力(煤基质外力)增大,裂隙宽度减小,煤储层渗透率降低;而流体压力降低,煤层气解吸,煤基质发生收缩,产生煤基质内力,裂隙宽度增大,煤储层渗透率增高。为了探讨煤基质内外应力与煤基质变形特性的关系,开展了三轴力学实验和吸附膨胀实验,根据实验结果的分析和总结,提出了煤基质自调节效应的新观点,构建了煤基质内外应力耦合作用下的自调节模式。研究成果为煤层气的有效开采提供了理论基础。

An experimental study on the self-regulating effect of coal matrix

Coal reservoir permeability is one of the key parameters to determine the success or failure of coalbed methane exploitation. Taking coal matrix as the research object, according to the difference of the stress sources, a new concept of internal and external stress of coal matrix is put forward. The dynamic variation of the permeability of coalbed layers during the coalbed gas recovery resulted from the internal and external stress of coal matrix. With gas recovery, the effective stress (external stress of coal matrix) increases, the fracture width reduces, thus the permeability of coalbed layers decreases, and the release of gas will lead to the coal matrix shrinking, resulting in internal stress of coal matrix, which leads to the increase of both the fracture width and the permeability of coalbed layers. In order to study the relationship between the internal and external stress and coal matrix deformation characteristics, the triaxial mechanical experiments and adsorption expansion experiments are carried out. According to the analysis of experimental results, a new viewpoint of the self regulating effect of coal matrix is proposed, and the self regulating model of coal matrix under the coupling effect of internal and external stress of coal matrix is constructed, which may provide theoretical basis for further study and effective gas exploitation.