Shoal Development within the Epicontinental Carbonate Platform, Jia 2 Member, Lower Triassic, Moxi Gas Field, Central Sichuan Basin

Key words: 
• distribution

Abstract: The oil and gas exploration for oolitic shoals in the Triassic platform margin in Sichuan Basin makes important breakthrough and headway. This has aroused the research interest for shoal body within wide carbonate platform. Taking the Bed A of the Jia2 Member in the Moxi Gas Field in central Sichuan Basin for an object of study, this article summarizes the development characteristics of the intraplatform shoal in the epicontinental carbonate platform, based on the analysis of the data of logging and coring in the region of interest. The intraplatform shoal is characterized by the shallowingupward sequence. A single shoal body is less than 4 meters in the thickness. Besides, the cumulative thickness and horizontal succession are both relatively inferior. The further research proves that the development and distribution of the oolitic shoals within the platform are controlled by the depositional palaeogeomorphology, water depth, turbulent of sea water and fluctuation of sea level. Meanwhile the research also indicates that the inherited palaeohigh within the epicontinental carbonate platform is benefit to develop the shoal vertically and horizontally. However, the palaeogeomorphologic differentiation causes horizontally great variation of intraplatform shoal. All of the investigation has laid a solid geologic foundation for the further exploration.