页岩储层含气性评价及影响因素分析——以涪陵页岩气田为例

Evaluation of gas content in shale reservoirs and analysis of influencing factors in Fuling shale gas field

页岩气赋存形式多样,主要以游离态、吸附态为主,且不同赋存状态的页岩气主控因素差别较大,页岩含气性综合评价体系尚未形成。为此,依据四川盆地东部涪陵国家级页岩气示范区生产特征实际资料,以五峰—龙马溪组页岩为研究对象,主要通过地球化学分析测试、岩石物性测试、等温吸附实验和岩心现场解吸等手段,研究影响不同赋存状态的页岩含气性的主控因素,提出页岩含气性评价主要包括2大类6项参数的评价指标:直接指标(实测含气量、气测显示值和含气饱和度)和间接指标(孔隙度、电阻率和地层压力)的含气性定性—半定量评价体系。

Shale gas has various forms of occurrence,mainly in the free and adsorbed state,and the main controlling factors of shale gas in different occurrence states are quite different.Comprehensive evaluation of shale gas systems has not yet been documented.Therefore,the actual data of production characteristics of Fuling national shale gas demonstration area in the east of Sichuan Basin were studied by means of geochemical analysis,petrophysical testing,isothermal adsorption experiments and on-site desorption of shale in the Wufeng-Longmaxi formations.The main controlling factors of shale gas content in different occurrence states were identified as the following.The evaluation of shale gas content mainly includes the evaluation indexes of six categories and six parameters:direct index(measured gas content,gas detection value and gas saturation)and indirect indicators(porosity,resistivity and formation pressure)for gas qualitative and semi-quantitative evaluation system.