Sedimentary Anatomy Of Thick Sandstones On The Braided Delta Front

Shan-gan-ning basin is a large Mesozioc basin , in which there are rich energy resources and Yanchang formation is one of important oil-bearing Formation. Lithology deposits are the most tapes of deposits, which is rigorous controlled by sedmentary facies. The paper studies The Thick Main Sandbodies through three aspecs: SEDMENTARY FACIES, ARCHITECTURE COMBINATION AND CHARACTERS OF RESERVOIRS.Firstly, the study of The Microfacies Combination and Characteristic of Main Sandbodies in Chang8 oil reservoir sets shows the braided delta front are developed in Yanchang formation in Xifeng area of Shan-gan-ning basin, which is mainly composed of the submerged distributry channels, mouths bars. It can be divide into submerged distributary channels section, submerged distributary channels together with mouth bars section and mouth bars section. Based on reaserch of submerged distributry channels and mouth bars, the abundant sandbodies conformation can reflect different sedimentary envirments. For instance, submerged distributary channels section are composed of trunk Sandbodies, campaniform Sandbodies and campaniform-trunk Sandbodies act. The relationship between the characteristics and quality of the reservoirs and their physical property and oil-bearing property is analyzed and the law of oil and gas distribution in the area is described, which provides reliable basis for the further exploration and development of the area.In light of the study of 3D architecture composed by A. D. Miall, the 3D architecture with same origins in the exposure are studied and a related model is constructed. The main sand body is divided into different levels of interfaces andarchitecture units .We recognized the 6 interfaces and 9 architecture units.In the end, on the base of the investigation on the characteristic of petrologic, porosity and percolation of different kinds of reservoir, we conclude that low porosity and percolation is the Characteristic of the reservoir in Chang 8 oil reservoir sets in Longdong area. Bar over river and river over bar are the high quality reservoirs. I discuss the effect that environment works on reservoir quality.