四川盆地东南缘富页岩气构造类型及保存主控因素

Structural types and main controlling factors for preservation of rich shale gas formation in southeast of the Sichuan Basin

四川盆地东南缘富页岩气构造类型丰富、保存主控因素复杂。分析川东南地区富页岩气构造结构、变形特征及分布规律,构建垂向断层封闭和横向页理封闭三维模式,研究富页岩气构造保存主控因素。结果表明:川东南地区发育正向构造、负向构造及断层遮挡斜坡等富页岩气构造,自盆外、盆缘内侧至盆内呈现紧闭向斜、宽缓向斜、正向构造、断层遮挡斜坡、低幅隐伏背斜的变化规律。箱状背斜页岩气保存主控因素为断层封闭性;圆弧状背斜保存主控因素为背斜曲率;非倒转向斜页岩气保存主控因素为目的层埋深和岩层倾角;倒转向斜、断层改造向斜和断层遮挡斜坡三类富页岩气构造类型的保存主控因素为断层封闭性、目的层埋深和岩层倾角。川东南地区盆缘内侧正向构造为有利富页岩气构造类型。

By the combination and transformation of multi structural systems,the structural types of rich shale gas is diversification,and the main factors of preservation are complex in the southeast of Sichuan Basin.In order to clarify the structural type,reveal the distribution law and find out the main control factors of shale gas preservation,the structural structure,deformation characteristics and distribution law of shale gas are analyzed carefully in Southeast Sichuan Basin,and a three dimensional model of vertical fault sealing and horizontal foliation sealing is constructed to study the main control factors of shale gas preservation.The results show that there are many shale gas rich structures in Southeast Sichuan Basin,such as positive structure,negative structure and fault block slope,which show the change rules of tight syncline,wide and gentle syncline,positive structure,fault block slope and low amplitude concealed anticline from outside of the basin to inside of the basin.The main controlling factors is the fault sealing to box anticline for shale gas preservation,the curvature to circular arc anticline,the objective layer depth and rock dip angle to the non-inverted syncline,the fault sealing,objective layer depth and rock dip angle to the inverted syncline,fault reconstruction of syncline and fault screened slope.The positive structure is positive ones for shale gas rich structure on the inner side of basin margin in Southeast Sichuan Basin.