The Sedimentary Facies Study Of Lower Jurassic Da’anzhai Memberin Fuling Area,Eastern Sichuan Basin

Eastern Sichuan region is in favor of oil and gas reserves in Sichuan Basin. The Ziliujing formation, Lower Jurassic in eastern Sichuan is a major oil and gas bearing stratigraphy, it has rich oil and gas resources and show good prospects for oil and gas exploration. The research carried out for this project has obvious economic and significant social benefits.Objecting on eastern Sichuan basin Da’anzhai member, Lower Jurassic and based on the profile measurement in the field, drilling core description, thin section identification, and combined with the logging and seismic data and guided by regional structure and sedimentary basin analysis and sedimentology theory and previous research by other people, the characteristics of the Da’anzhai and it’s distribution law are analyzed in detail and the favorable areas for hydrocarbon are effectively predicted. According to the ideas of "Point-Line-Face", The research is carried out from single well to wells connecting analysis. From the aspects of petrology, sedimentary facies marks and seismic responding characteristics, the sedimentary facies distribution maps are finally prepared, thus providing technical support for the further exploration and development of the study area.Through the study on sedimentary characteristics of Da’anzhai member, the following important progress and cognition are obtained: ① the sedimentary system of Da’anzhai member in Fuling region, east Sichaun are lacustrine with carbonate the main, 5 sub-facies of half deep-deep lake, slope, carbonate shallow lake, terrigenous clastic shallow lake and lakeshore and 9 micro-facies are identified, sedimentary facies model suitable for the region are set up; ② according to the principle of sequence stratigraphy, the stratigraphy sequence of Da’anzhai member in Fuling region, east Sichuan region can be classified into 1 long term, 5 middle term and numerous short term which are equivalent to the scale of subsequence, the study area experienced from the shore-shallow lake to half-deep lake and back to shore-shallow lake. This is a complete lake transgression to regression evolution process; ③ On the establishment of the sequence framework, and combined with single well facies and well-correlation analysis and grain limestone thickness, stratigraphy thickness and seismic facies, the Da’anzhai sequence-paleogeographic maps are drawn, and the distribution features time-space evolution of sedimentary facies are systematically analyzed. ④ On the above all research results and previous data, the location of the stratigraphy of Da’anzhai member in favor ofunconventional reservoir and shale gas-oil concentration as of "sweetheart" are predicted.