QNDN1井煤层气排采的流体效应分析

An analysis of fluid effect during coalbed methane drainage in the well QNDN1

为了研究煤层气排采时原位煤储层流体的动态效应,基于煤储层动水孔隙度、含气饱和度等储层物性实测成果,结合中国第一口地面多分支煤层气水平井——QNDN1井的排采数据,通过气、水产能及储层压力曲线的耦合分析,探讨了煤层气井排采时储层压力的传播特征;估算了煤层气单井排采范围内的重力水量,水溶气、游离气量;划分了煤层气井排采的游离气运移阶段和煤层气的解吸阶段;指出煤层气排采流体效应的主要影响因素是储层压力和受煤孔径结构控制的煤层气解吸特征。该研究成果对煤层气井排采制度的确定具有指导意义。

In order to study the dynamic effects of in-situ fluids in coal beds during coalbed methane (CBM) drainage,the physical properties of coal reservoirs such as flowing-water porosity and gas saturation are measured.In addition,the drainage data of the well QNDN1,the first multi-lateral horizontal CBM well in China,are collected.Based on these data,propagation of reservoir pressure during CBM drainage is studied through correlative analysis of gas and water productivity and reservoir pressure.Gravity water volumes,water-soluble gas and free gas volumes within single well drainage area are calculated.Free gas migration stages and CBM desorption stages are defined.It is pointed out that coalbed pressure and CBM desorption features controlled by coal's aperture structure are the major factors influencing fluid effects of CBM drainage.The results of this study can be used to guide the design-making of CBM drainage scheme.