1. School of Petroleum Engineering,China University of Petroleum (East China),Qingdao　 266580,China; 2. Shanxi Coalbed Methane Exploration & De-velopment Branch,PetroChina Huabei Oilfield Company,Changzhi　 062552,China

目前的煤层气藏物质平衡方程忽略了煤层气吸附-解吸实验中的吸附滞后现象,大多基于煤层气吸附与解吸过程完全可逆的认识所建立的,与实际煤层气藏的排水—降压—解吸开采过程明显不符,从而无法有效指导煤层气藏的开发规划决策或后续开发方案调整。基于煤层气的吸附滞后现象分析,提出了吸附滞后效应概念,进而建立考虑吸附滞后效应影响的煤层气藏物质平衡方程,并将其应用于某煤层气藏的原始地质储量、可采储量和采收率等评价指标预测。实例应用表明,采用物质平衡方法确定煤层气藏地质储量时,若忽略煤层气的吸附滞后效应,采用吸附等温曲线参数将可能会低估煤层气藏的地质储量值却高估采收率值,造成巨大的预测误差;与之相反,采用考虑吸附滞后效应的煤层气藏物质平衡方程确定的气藏地质储量值及平均含水饱和度变化值与实际值之间的误差较小,说明了所构建的煤层气藏物质平衡方程的有效性和正确性,可准确地评价煤层气藏的可采储量和采收率评价指标,对于煤层气藏后续开发规划实施和开发方案调整具有积极的指导作用。

Previous material balance equations (MBEs) were established under the assumption that the adsorption and desorption process of coalbed methane (CBM) is completely reversible and the adsorption hysteresis phenomenon ob-served in CBM adsorption / desorption experiment was neglected,which is obviously not consistent with the actual de-pressurization process of CBM reservoirs by water drainage. This paper proposed the concept of adsorption hysteresis effect based on laboratory observation and analysis of the potential mechanisms. Furthermore,an improved MBE model of CBM reservoirs considering the adsorption hysteresis effect was established,and it was applied in predicting the original gas in place (OGIP),recoverable reserves and recovery factor of some actual CBM reservoir. The results show that MBEs may significantly underestimate the OGIP while overestimating the recovery factor if the adsorption hystere-sis effect is not included in the calculations. Conversely,the calculated OGIP and average water saturation are in good agreement with the actual values using the new MBE model that incorporates the adsorption hysteresis effect. There-fore,the validity and accuracy of the new MBE model is proved,and then the proposed material balance method can be potentially applied in evaluating the recoverable reserves and recovery factor of CBM reservoirs,which would also play a major guiding role in the subsequent development planning and adjustment of CBM reservoirs.

国家自然科学基金资助项目(11302265)；中央高校基本科研业务费专项基金资助项目(14CX02046A)；

ZHANG Xianmin,FENG Qihong,ZHANG Jiyuan,et al. Establishment and application of material balance equations for coalbed methane reservoirs considering adsorption hysteresis effect[ J]. Journal of China Coal Society,2017,42(10):2662 -2669.