川西坳陷形成演化及其与油气的关系

川西坳陷是指四川盆地西部晚三叠世以来形成的前陆盆地。受周缘山系多期次构造变形的影响，川西前陆盆地的演化明显具有多期次性。根据盆地沉积和构造演l匕特征，川西前陆盆地的演化可分为六个阶段。川西前陆盆地的演化与龙门山和秦岭造山带的活动密切相关，在快速沉降期，形成了良好的烃源岩和储集岩；在相对稳定期，物源供给有限，表现为湖沼相，以泥质沉积为主，形戎了良好的区域盖层。多期次的构造运动和适度的变形，为油气运移、聚集和圈闭的形成打下了良好的基础。

Forming evolution of western Sichuan depression and its relation with oil and gas

Western Sichuan Depression is a foreland basin developed in the west of Sichuan basin since late Triassic. Influenced by multiple stage structural deformation of surrounding mountain systems, evolution of foreland basin in western Sichuan has obviously multiple stage features. Based on the features of basin sedimentation and structural evolution, the evolution of the foreland basin in western Sichuan has six stages, the evolution is relative closely to orogenic activities of Mountain Longmen and Qinling. During quick subsidence stage, the favorable hydrocarbon source rocks and reservoir rocks were formed; during relative stable stage, it was characterized by lacustrine facies and dominated by shaly deposition with limited source, thus forming favorable regional seal. Owing to tectonic activity with multiple stages and appropriate deformation, it lays a good foundation for hydrocarbon migration, accumulation and trap forming.