1. School of Energy Resources,China University of Geosciences (Beijing),Beijing　 100083,China;2. Coal Reservoir Laboratory of National Engineering Re-search Center of Coalbed Methane Development & Utilization,Beijing　 100083,China

基于中—高煤阶煤储层欠饱和特性及煤层气井生产数据,以临界解吸压力为关键参数节点,揭示了中—高煤阶煤层气系统物质能量动态平衡机制及其对煤层气开发过程的控制作用。结果表明:基于上述机制可以实现储层压力和含水饱和度实时监测、煤层气井单井可采储量计算、储层渗透率(包括绝对渗透率、相对渗透率、有效渗透率)动态预测、产能动态数值模拟等4方面现场需求;煤储层相对含气量(吸附态气体饱和度)越高,储层压力与含水饱和度下降越快,煤层气越容易解吸产出;临界解吸压力后,煤层气井生产时间越长,储量计算准确性越高;在整个煤层气生产过程中,煤储层渗透率被统一为储层压力的函数,欠饱和相渗曲线能更好地反映煤储层正负效应及气体滑脱效应;在产能预测方面,欠饱和相渗模型较饱和相渗模型更加准确,精确度更高。

Based on the unsaturated characteristic of medium-high rank coal reservoirs and coalbed methane ( CBM) well production data,the material and energy dynamic balance mechanism in middle-high rank CBM systems was re- vealed by considering the critical desorption pressure as a key parameter. The control action of this mechanism on practical CBM development was also analyzed. Results show that four aspects of the requirements in the field can be realized through using above mechanism,including the real-time monitoring of reservoir pressure and water saturation, the single CBM well recoverable reserves calculation,the reservoir absolute or relative as well as effective permeability dynamic prediction and the productivity dynamic numerical simulation. The higher the relative gas content ( the ab- sorbed gas saturation) of the coal reservoirs is,the faster the reservoir pressure and water saturation decline,the easier the CBM desorption is. After the reservoir pressure is under a critical desorption pressure,the longer production time could bring more accurate reserves computation. In the whole process of CBM production,the coal reservoir permeabili- ty are unified as the function of reservoir pressure and the unsaturated effective permeability curves can better reflect the positive and negative effects as well as the gas slippage effect. Meanwhile,the unsaturated effective permeability model is more accurate and precise than that of the saturated effective permeability model in the CBM well productivity prediction.

国家科技重大专项资助项目(2016ZX05042-002)；国家自然科学基金资助项目(41530314)；中央高校基本科研业务费专项基金资助项目(2652015331)；

Tang Dazhen,Zhao Junlong,Xu Hao,et al. Material and energy dynamic balance mechanism in middle-high rank coalbed methane (CBM) systems[J]. Journal of China Coal Society,2015,40(1):40-48.