煤储层厚度与其渗透性及含气性关系初步探讨

煤储层厚度对其渗透率和含气性具有显著影响。研究表明:华北石炭二叠系煤储层厚度与渗透率的关系明显分布在两个区域,构造煤发育的煤储层其厚度与试井渗透率之间具有负相关趋势,原生结构保存完好的煤储层其厚度与试井渗透率之间关系以渗透率0.5 mD为界,表现出截然相反的两种相关趋势;我国部分地区煤储层含气量具有随厚度增大而增高的规律;我国具有商业性开发价值的煤储层的临界渗透率似乎应在0.5 mD左右。煤储层厚度与渗透率之间关系分别受控于沉积作用、地应力、煤级煤岩特征或构造变形特征,但不同地质背景条件下的主要控制因素可能有所侧重。煤储层厚度越大,煤层气向顶底板扩散的阻力就越大,这也许就是某些地区煤储层厚度与含气量之间具有正相关越势的根本原因。 

RELATIONSHIP OF COAL RESERVIOR THICKNESS AND ITS PERMEABILITY AND GAS-BEARING PROPERTY

The permeability and gas-bearing property of coal reservoir are remarkably affected by its thickness.The thickness of the coal reservoirs in the Morth China plots their pemeability in different two patterns,that of the structurally-destroyed coal reservoirs is negatively related to the well-tesing permeability in tendency,but there exist two relationships with reverse trends in the coal reservoirs with completely-original structure taking 0.5 mD permeability as a threshold value.The coallbed methane content in some area of China shows the increasing pattern with increasing thickness.The threshold permeability of the commercially valuable coal reservoirs in China should be seemingly defined as 0.5 mD or so.