The division to microfacies in middle-fan of subaqueous fan in continental basin: a case study from Liangjialou subaqueous fan in Shinan area of the Dongying sag

Based on elaborate correlation to substratum of Es₂⁹ sand group in Shinan area, Dongying sag,the middle-fan of Liangjialou subaqueous fan can be divided in 9 micro-facieses: braided channel, braided bar, "point bar", lateral bar, lateral branching channel, end bar of branching channel, washover fan, low slope, high slope. There are obviously differences in changes of sand-grain-size and plane distribution among these microfacieses, the formation of braided bar, "point bar" and lateral bar were derived from lateral migration of braided channel with little gradient and flatter subaqueous landform. The elaborate division to microfacieses can help us to realize deposition of subaqueous fan and the distribution of remaining oil, and adjust the development plan to oil field.