煤变质程度对煤储层物性的控制作用

通过对大量煤岩样品的压汞实验和低温氮吸附实验测试结果的系统分析，讨论了煤变质程度对煤储层物性的控制作用。结果发现：煤样的压汞孔隙度随煤级的升高呈现出高-低-高的变化趋势；孔喉平均直径小于1 μm的孔隙结构在各种不同煤级的样品中均大量分布，而孔喉平均直径大于1 μm的孔隙结构则仅在中低煤级样品中大量分布，在无烟煤中更是很少见到；在中低煤级阶段，随着煤变质程度的增高，低温氮测试的煤比表面积逐渐降低，到无烟煤阶段，煤的比表面积又开始增加。结论认为：煤的孔隙度、孔隙结构和比表面积均受煤变质程度的控制，且在烟煤与无烟煤的交界处发生突变。

CONTROL EFFECT OF COAL METAMORPHIC DEGREE ON PHYSICAL PROPERTIES OF COAL RESERVOIRS

Through analyzing the results of mercury injection experiments and static cryogenic nitrogen adsorption experiments, this paper discusses the control effect of coal metamorphic degree on the physical properties of coal reservoirs. The following understandings are obtained. a. the porosity values of coal samples obtained from mercury injection experiments show a trend of high low high variation along with the rising of coal rank; b. pores with an average diameter of throat smaller than 1 μm are extensively distributed in coal samples of various coal ranks, while that with an average diameter of throat larger than 1 μm are extensively distributed only in coal samples of medium and low coal ranks, and are rare in anthracite. c. for coals of medium and low ranks, their specific surface area measured through cryogenic nitrogen test lowers progressively along with the increase of metamorphic degree, while for anthracite, their specific surface area increases. It is concluded that the porosity of coal, pore structure and specific surface area are all controlled by metamorphic degree and they change abruptly on the border between bituminite and anthracite.