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四川盆地上二叠统是发育在下二叠统侵蚀面上的一套海侵沉积。其碳酸盐岩沉积主体在川东及鄂西地区，沉积环境属碳酸盐缓坡。该沉积体系包括碳酸盐浅缓坡（海陆交互带）、碳酸盐深缓坡（细分为外带和内带）、海槽（盆地）和环海槽陆棚边缘带。这些沉积相带自四川盆地西南向东北大致呈同心弧状顺次展布，并随海侵的发展逐渐向西南方向迁移。至长兴期，受南秦岭裂陷洋强烈拉张的影响在川东北部形成开江—梁平碳酸盐海槽，并在陆棚边缘带和深缓坡带分别发育了陆棚边缘礁和点礁，由此开始了由碳酸盐缓坡向碳酸盐台地转化的过程。陆棚边缘礁带是生物礁发育的有利相带。陆棚边缘礁的个体明显大于缓坡内的点礁，分布密度大，是形成大中型生物礁气藏的有利相带。到长兴期末，这些陆棚边缘礁仍未能相互连接构成连续的障壁，致使四川盆地晚二叠世的沉积环境未能最终由碳酸盐缓坡转变为碳酸盐台地。
The Upper Permian in the Sichuan Basin was a set of transgressive sediments that developed over the Lower Permian erosions. The carbonate sedimentary bodies are mainly in eastern Sichuan and Western Hubei and the sedimentary environment is carbonate gentle slope. The sedimentary system includes shallow gentle carbonate (continental-continental interaction belt), carbonate deep slope (subdivided into outer zone and inner zone), trough (basin) and annular trough shelf margins. These sedimentary facies belonged to the concentric arcs from southwest to northeast of Sichuan Basin in sequence, and gradually migrated to the southwest with the development of transgression. In the Changxing period, the Kaiping-Liangping carbonate trough was formed in the northeastern Sichuan by the strong pull of the southern Qinling rift ocean. At the marginal zone and deep gentle slope of the shelf, the marginal reef and the reef of the shelf were developed , Thus beginning the process of carbonate platform conversion to carbonate platform. The reef edge of the shelf is a favorable facies belt for reef development. The individuals in marginal reefs of the shelf are obviously larger than the reefs in the gentle slope, which have large distribution density and are favorable facies belts for forming large and medium-sized biohermal gas reservoirs. By the end of Changxing period, the marginal reefs of these shelf can not be interconnected to form a continuous barrier, resulting in the Late Permian sedimentary environment of Sichuan Basin failed to change from carbonate ramp to carbonate platform.