The Study Of Sedimentary Facies Of Feixianguan Formation In Lower Triassic Series, Dazhu-Daxian Area, Sichuan Basin

Dazhu-Daxian area is located in the east of Sichuan basin, with the controlled area of more than 3000 square kilometers. The earlier exploration results in the study area show that it has rich hydrocarbon source. Now, Feixianguan Formation, Lower Triassic series, is one of the key target formation of the rolling exploration and development in east Sichuan basin.Under the guidance of principles and methods of Carbonate Sedimentology, Sequence Stratigraphy and Lithofacies Palaeogeography, multiple methods of outdoor and indoor, macroanalysis and microanalysis have been used in the research aspect of formation, rocks, sedimentary facies and the controlling of sedimentary facies on oolitic beaches in Feixianguan Formation in Dazhu-Daxian area. Based on the study of drilling and outcrop data, from which deduced the depositional framework, and main types and characteristics of sedimentary facies in Feixianguan Formation. It can recognize there basic facies belt including carbonate platform, continental shelf (slope) and trough etc, and carbonate platform facies can further classified into five subfacies such as tidal flats, open platform, beach, stricted platform (lagoon) and marginal platform etc. Based on the analysis of sedimentary facies in individual wells and the correlation of four cross sections of sedimentary facies, it is elaborated the development law of sedimentary facies of Feixianguan Formation in vertically and laterally within Dazhu-Daxian area. By the method of single-factor analysis, it summarize facies distribution and evolution law of Feixianguan Formation after thorough study of three single factors that could embody sedimentary environment and facies, that is the thickness of formation, oolitic limestone and dolomite, and a sedimentary facies model is established, and the controlling of sedimentary facies on oolitic beach distribution is discussed.