Coal Reservoir Laboratory of National Engineering Research Center of CBM Development & Utilization,China
University of Geosciences( Bejing) School of Energy Resources,China University of Geosciences( Beijing) Petro
China Huabei Oilfield Company

为了更加准确地计算煤储层渗透率变化,从煤储层渗透率控制机理出发,以物质平衡原理为基础,分别建立有效应力、基质收缩、气体滑脱3种地质效应的渗透率变化数学模型,推导得到了基于排采数据求煤储层渗透率变化的计算方法。以沁水盆地南部樊庄区块的4口煤层气井为例进行计算,研究了不同地质效应影响下煤储层渗透率变化特征,探讨了不同生产阶段煤储层渗透率变化的主控因素。研究结果表明:压降幅度与有效应力或基质收缩导致的渗透率变化率呈正相关;对于低压低渗煤层气藏,滑脱效应不容忽视;生产初期,煤储层渗透率受3种地质效应综合控制,当储层压力降低到2 MPa以下时,滑脱效应起主导作用。

In order to calculate the changes of permeability of coalbed reservior more accurately,three mathematical models were established by considering the effect of stress sensitive,matrix shrinkage and gas slippage on the permeability of coal based on the controlling mechanism of coal reservoir permeability and material balance eq uation. A theoretical method for permeability of coalbed with drainage data was finally developed. Four wells from Fanzhuang Block in southern Qinshui Basin were then e mployed for a case study,in which synthesized results were obtained about variation of permeability under different geological effect and the main controlling factors of coal reservoir permeability during different production stage were analysed. The results showed that the pressure drops was positively correlated with the rate of permeability C hange made by effective stress or matrix shrinkage; the effects of gas slippage could not be ignored under low reservoir pressure and low permeability condition; in early st age,CBM permeability was controlled by three effects synthetically and the slippage effects was dominant under reservoir pressure of lower than 2 MPa.

国家科技重大专项资助项目(2011ZX05034-001)；国家自然科学基金资助项目(U1262104)；北京高等学校青年英才计划资助项目(YETP0660)；