黔西—滇东地区不同变形程度煤的孔隙结构及其构造控制效应

Pore Structures and Structural Control of Coals with Different Degrees of Deformation From Western Guizhou and Eastern Yunnan

基于黔西—滇东地区上二叠统80件煤样的压汞实验数据,结合煤层构造变形特征的矿井观测,探讨了煤中孔隙结构及其构造控制效应。结果表明,区内煤的孔隙度较高,以微孔和过渡孔为主,中孔和大孔发育的差异性加大。根据压汞曲线形态和阶段孔容的分布模式,将煤中孔隙结构划分为五种类型,即平行型、反S型、尖棱型、双S型和双弧线型。平行型和反S型的煤体结构主要为原生结构煤和碎裂煤,经构造改造后孔隙度和孔容均大幅增高,且连通性好;尖棱型为碎裂煤和碎斑煤,孔隙度和孔容均较高,连通性较好;双S型和双弧线型为糜棱煤、碎斑煤和揉皱煤,煤体破碎严重,孔隙连通性很差。构造变形所造成的煤的孔隙度和总孔容的整体增高和阶段孔容的差异性增长是煤储层孔隙结构分异的主要因素,且随着构造变形的增强其对煤体破坏的主要变形作用尺度有逐渐减小的趋势。

To evaluate pore size distribution and structural control effect of Late Perman coals from Western Guizhou and Eastern Yunnan, we provide an analysis of the mercury intrusion porosimetry data and the structural deformation characteristics of coal seam based on 80 coal samples. The pores of coal are mainly composed of micropores and transitional pores, with high porosity. The macropores and mesopores vary greatly. According to shapes of intrusive mercury curves and pore size distributions, pore structure can be divided into five types. The parallel type and reverse S type are primary and cataclastic structural coals, with enlarged porosity and good pore connectivity induced by the structural modification; the angular type is cataclastic and mortar structural coal, with relatively high porosity and pore connectivity; the double S type and double curvature type are mylonitic, wrinkle and mortar structural coals, with crushed coal body and poor pore connectivity. The overall increase of total pore volume and varying increase of stage pore volume, caused by structural deformation, are primary factors for the differentiation of coal pore structure. With the increase of structural deformation, the deformation scale of coal is gradually reduced.