不同层理方向的煤岩渗透特性研究

摘要

Shanxi group Ⅱ1 coal seam in Jiaozuo has the characteristics of big thickness,simple construction and distributional stability with large exploitation potentiality.The acquisition of permeability parameters of the target coal seam is a precondition for hydraulic fracturing fracture prediction.Laboratory test to study the permeability characteristics of natural cores of the block was adopted.The results show that the reservoir permeability is good which is conducive to the implementation of hydraulic fracturing.The main factors influencing the permeability are bedding direction,porosity,the development degree of crack and micro fracture.The hole-through degree of crack and micro fracture has the largest impact and the bedding direction takes second place.For the large differences on the permeability of the directions parallel to and vertical to the bedding,the parallel and series choke systems of water and gas seepage are established.It reveals the primary reason for permeability difference is bedding structures.The research can provide theoretical support for determining the reasonable mining method of the target coal seam and confirming the initiation and propagation rules of hydraulic fracture.%焦作矿区的山西组二1煤层具有厚度大、结构简单、分布稳定等特点,其开采潜力较大.对目标煤层渗透率参数的获取是对水力压裂裂缝预测的先决条件.采用室内试验,对该区块的天然岩芯进行渗透特性研究.结果表明:储层的渗透性较好,有利于水力压裂改造的实施.影响渗透率的主要因素为层理角度、孔隙度、裂纹及微裂缝的发育程度等,其中裂纹和微裂缝的贯通程度对渗透率影响最大,层理角度次之.针对平行层理方向和垂直层理方向上渗透率的较大差异,分别建立了水气渗流的并联和串联阻流模型,揭示了影响渗透特性差异的主要原因为层理构造.本研究可为目标煤层确定合理的开采方式及确定水力裂缝的起裂与扩展规律提供理论支持.