复杂构造区页岩气藏地质特征与效益开发建议——以四川盆地及其周缘五峰组—龙马溪组为例

以四川盆地及其周缘五峰组—龙马溪组页岩气藏为例，总结了复杂构造区高压、超压页岩气田的地质特征，对比分析了常压页岩气藏与高压、超压页岩气藏的异同点。根据构造改造和气藏的分布特点，提出了常压页岩气藏的分类方案，将中国南方常压页岩气藏分为盆内型、盆（内）缘过渡型和盆外残留型3种类型。研究认为，盆外残留型页岩气藏具有地层连续分布面积小、裂缝发育、地层压力系数偏低、游离气占比较低、地应力较小和两向水平应力差异较大等特点。对盆地外复杂构造区的常压页岩气藏，提出TOC大于3%、孔隙度大于3%和含气量大于3 m³/t可作为效益开发的选区依据。

Geological characteristics and beneficial development scheme of shale gas reservoirs in complex tectonic regions:a case study of Wufeng-Longmaxi formations in Sichuan Basin and its periphery

Taking the Wufeng Formation-Longmaxi Formation shale gas reservoirs in Sichuan Basin and its periphery as examples, this paper summarizes the geological characteristics of high-pressure and over-pressure shale gas fields in complex tectonic regions, compares and analyzes similarities and differences between normal pressure and high-/over-pressure shale gas reservoirs. According to the distribution characteristics of tectonic reworking and gas reservoirs, this paper proposes a classification scheme for normal pressure shale gas reservoirs, and divides the normal pressure shale gas reservoirs in southern China into three types, i.e., intra-basin type, basin margin transition type and extrabasinal residual type. The research shows that the shale gas reservoirs of the extrabasinal residual type has the characteristics of small continuous distribution area, well-developed fractures, low formation pressure coefficient, low free gas ratio, small crustal stress and large difference in bidirectional horizontal stress. For the normal pressure shale gas reservoirs in complex tectonic regions outside the basin, this paper proposes that TOC greater than 3%, porosity above 3%, and gas content more than 3 m³/t can be used as the basis for selecting beneficial development zones.