新型裂缝性页岩气藏物质平衡方程

A new material balance equation for fractured shale gas reservoir

王怀龙 张茂林 郭沙沙 梅海燕

西南石油大学油气藏地质及开发工程国家重点实验室，四川 成都 610500

State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu 610500, China

前人推导的物质平衡方程往往忽略了吸附相所占的孔隙体积，因而多低估了页岩气藏的单井控制储量。文中在考虑吸附相所占体积的基础上，调研了国内外学者研究的吸附相密度值，运用质量守恒方法考虑了吸附相体积随地层压力的变化，又根据Langmuir吸附定律及体积守恒原理建立了裂缝性页岩气藏物质平衡方程。通过实例计算得知，发育裂缝的页岩气藏，裂缝中的自由气储量占总储量的24.28%~33.29%，同时基质中的储量主要由吸附相提供。由此可知，利用考虑了双重孔隙和吸附相体积2个因素的裂缝性页岩气藏物质平衡方程，能够得到气藏基质、裂缝、吸附相的地质储量；同时随着吸附相密度的增加，基质中的自由气、吸附气储量以及总储量逐渐增加，裂缝中的自由气储量逐渐减少。

Since pore volume occupied by adsorbed phase is often overlooked for former material balance equations for shale gas reservoirs, the controlled reserves of single well are underestimated. On the basis of considering the adsorbed phase volume, this article researches the adsorption density value at home and abroad. Using the mass conservation method, it considers the change of the adsorbed phase volume with the formation pressure. According to Langmuir adsorption model and volume conservation, the material balance equation for fractured shale gas reservoir is established. A real case calculation result shows that free gas reserves account for 24.28%?鄄33.29% of total reserves in fractured shale, matrix reserves are mainly of adsorption phase. Therefore, the geological reserves for matrix, fracture and adsorption phase of gas reservoir can be obtained by the material balance equation for fractured shale gas reservoir considering dual porosity and adsorbed phase volume. With the increasing of adsorbed phase density, the free gas reserves in matrix, adsorbed gas and total reserves are increasing and the free gas reserves in fracture are decreasing.

10.6056/dkyqt201502014