煤岩储层渗透率动态变化模型

摘要

煤层气开采过程中,煤岩储层渗透率随压力降低不断变化.在考虑有效应力、基质收缩以及滑脱效应对渗透率影响的基础上,建立煤储层渗透率动态变化模型.研究结果表明:开采初期,储层压力降低,有效应力增大,渗透率降低；煤层气解吸,煤岩基质收缩,渗透率回弹；开采后期,有效应力与基质收缩的影响逐渐减弱,滑脱效应占主导地位,渗透率明显增加.%The permeability of coal seam constantly changes with the decrease in pressure in production. The dynamic permeability model rrnof coal seam is established based on the consideration of the impacts of effective stress, matrix shrinkage and slippage rrneffect on the permeability. In the initial period of the production, the coal seam pressure decreases and the effective rrnstress increases, which leads to the decrease in permeability and therefore coal seam gas desorbs, coal seam matrix shrink rrnand permeability rebounds; in the later stage of the production, the effects of the effective stress and matrix shrinkage rrntapers off and the slippage effect occupies the leading position, and therefore the permeability increases obviously.