沉积相及成岩作用对煤岩的储集性能都有重要控制作用,沉积相控制煤岩的灰分产率、煤岩显微组分,而这些因素又影响煤岩的储集性能。灰分与储集物性之间存在定量关系,灰分越多,储集物性越差。显微组分中,镜质组有利于割理的形成,镜质组含量越高,渗透性越好,孔隙度也越高。从暗煤到亮煤,总的趋势是镜质组含量增高、灰分产率降低,储集物性变好。华北地区石炭系-二叠系煤岩储集层主要形成于潮坪环境和三角洲环境,潮坪煤岩的储集物性优于三角洲煤岩,下三角洲平原沉积的煤岩储集物性优于上三角洲平原沉积的煤岩。处于潜流带和渗流带的煤岩,由于溶蚀作用强烈,其储集物性好,而处于深部缓流带的煤岩,由于胶结和压实作用强,储集物性差。因此,潜流带和渗流带是寻找优质煤岩储集层的有利部位。图5表1参24
The reservoir ability of coal rocks is controlled by both sedimentary facies and diagenesis. Sedimentary facies controls the content of ash and macerals, which affect the reservoir ability of coal beds. There exists a quantitative relation between ash production rate and porosity and permeability of the coal. The more the ash, the lower the porosity and permeability. Vhrinite is favorable to the formation of cleats. The higher the vitrinite content, the higher the porosity and permeability. From dull coal to bright coal, vitrinite tends to increase, ash tends to decrease, and porosity and permeability tend to increase. In the study area, coals were deposited in tidal flat and delta environments. Coals formed in tidal flats show higher porosity and permeability than those formed in deltas, and those formed in lower delta plains higher than those formed in upper delta plains. Due to denudation, coal rocks in the vadose and phreatic zones show better reservoir ability, while deeply buried coal beds, due to cementation and compaction, show poorer reservoir ability.