Study on crop, single well sequence and sedimentology of Badaowan formation in Bohu depression

Based on seismic data, field crop and drilling & logging data, the paper makes a sedimentology study on Bad-aowan formation of lower Jurassic of Bohu depression in Yanqi basin. After establishing three third - order sequence stratigraphic frameworks, the paper points out the sedimentary system composition was mainly shallow system based on delta- lacustrine swamp facies, with shallow water depth and limited distribution range. The identified sedimentary sources in the working area are as the follows; the first disperse source was developed from Ba-zhou coal mine to Sishilicheng area in the southwest. The braided river delta compounds from northeast carries the sediments enter into "lacustrine" which was developed in the middle- west, and accumulated as delta lobe. The second disperse source was developed in Baobei area of the northern depression, and the braided river delta compounds extended from northwest to southeast. The lake delta entered "lacustrine" and accumulated as small- middle type braided river delta. The third disperse source was developed in Benbutu area, and the braded river delta compounds also extended from northwest to southeast. When entering "lacustrine", it accumulated as small type shallow water lake delta. The fourth disperse source lies in the east of the depression and stretched from south to north, with the fan delta as the main form. The fifth disperse source lies in the east of Changqian 1 well, and stretched from east to west, but with limited scale.