关键词: 富集高产, 成藏条件, 吴家坪组, 二叠系, 红星地区, 四川盆地

Abstract: Constrained by geological conditions such as rapid facies change, thin thickness, and great burial depth of shale formation in the Permian Wujiaping Formation in Sichuan Basin, no major breakthrough has been made in unconventional gas exploration. In 2020, a risk exploration well HY-1HF was drilled and commercial gas flow of 8.9×104m3/d was obtained during well test, showing good exploration potential of shale gas in the Permian Wujiaping Formation in Hongxing area of eastern Sichuan Basin. In order to identify the main controlling factors for the enrichment and high yield of the Permian shale gas and its exploration implications, well drilling, logging and geochemical experiment data are analyzed. The study results indicate that deposits of deep-water shelf facies were generally developed in the second member of Wujiaping Formation (Wu 2 member), as well as high-quality organic-rich shale, with the characteristics of “four high and one thin”, namely, high TOC, high porosity, high gas content, high carbonate content and thin shale reservoir thickness (<20 m). Hongxing area is located in the tectonically stable zone, with good preservation conditions; In addition, the reservoir is conducive to fracture treatment owning to its rock mechanical features of low Young’s modulus and Poisson’s ratio. On the whole, it is a high-quality deep marine formation for shale gas exploration in combination with the excellent sealing conditions of roof and floor. The evaluation results conclude that Longjuba, Jiannan and Sanxing blocks are favorable exploration zones in Hongxing area of eastern Sichuan Basin.