Kaijiang-Liangping Pan-trough and seismic prediction of favorable facies belt

The prediction of bioherm in the Upper Permian Changxing Formation in the Sichuan Basin focused on geologic research in the 1980s and 1990s.It was common in the early stage of the study that wells being targeted at bioherm did not encounter bioherm,while wells that were not targeted at bioherm sometimes encountered bioherm.In recent years,a set of methods for identifying seismic facies of platforms at the end of Late Permian have been developed by using seismic facies prediction techniques of regional large section as well as geologic,drilling and log data.Evidences of platform-trough seismic facies have been identified,for the first time,on Chuanbei(north Sichuan),Chuanzhong(middle Sichuan) and Chuandong(east Sichuan) regional large seismic sections respectively.Based on these jobs,the favorable facies belts on biogenic buildups(reef facies,beach facies) are identified,the seismic facies prediction techniques of biogenic buildups on platform margin are summerized,and the palaeogeomorphology and sedimentary facies of Kaijiang-Liangping Pan-trough at the end of Late Permian in the Sichuan Basin are mapped.The study results show that the biogenic platforms on the periphery of the trough are long in extension and huge in exploration potential.Drilling results in the Wubaiti block of Chuandong(east Sichuan) area and the LG block in the Chuanzhong(middle Sichuan) area indicate that these techniques are suitable for the identification of the favorable targets of reef and beach facies in the Permian carbonates and for exploration planning.