典型构造煤变形特征及储集层物性

Deformation and reservoir properties of tectonically deformed coals

以鄂尔多斯盆地东缘渭北韩城地区的煤岩样品为研究对象,采用扫描电镜、显微CT观测和压汞、低温液氮吸附等实验方法对构造煤变形和孔隙结构进行表征,对块状构造煤进行吸附实验,研究构造煤储气机理。研究结果表明：碎裂煤、碎粒煤原始层理可辨,由剪切作用形成的煤颗粒较粗（1~3 cm）,脆韧性变形的鳞片煤和韧性变形糜棱煤煤岩原始层理和结构均被破坏,由剪切、层间滑动、揉皱形成的煤颗粒较细,构造变形造成的定向排列明显;随着构造煤变形程度的增大,孔容、孔隙比表面积和微孔比例从碎裂煤、碎粒煤到鳞片煤、糜棱煤逐渐增大,孔隙连通性增强。随构造变形强度增大,从脆性到脆韧性、韧性,煤对甲烷的吸附能力呈逐渐增强趋势,构造煤煤岩结构、孔隙-裂隙系统共同制约了煤对甲烷的吸附能力。

Tectonic deformation and pore structure characteristics of tectonically deformed coals （TDC） collected from the Hancheng area, Weibei block, eastern Ordos Basin were characterized through scanning electron microscope, micro-CT, mercury porosimetry and low-temperature nitrogen adsorption experiments. The isothermal adsorption experiment of lumpy TDC was also performed to investigate the gas storage behavior. The results show that the primary layer structure can be observed in cataclastic coals and granulated coals. These coals show sub-angular particles of 1-3 cm. For scaled coals and mylonitic coals, the primary structure and coal bedding have been destroyed, and the coal is sheared with directional arrangement of grains. The pore volume, pore surface area, micro-pore volume and pore connectivity increase with the increase in deformation extent. The CH4 adsorption capacity of coals shows an increasing trend from brittle deformation to ductile deformation. It is concluded that the coal structure, pore and fracture characteristics of TDC control the gas adsorption capacity of coals.