Sedimentary Facies of the Chang 2 Member of Yanchang Formation in Area A of Northern Shaanxi

¹ Zhidan Oil Production Plant, Shaanxi Yanchang Petroleum（Group）Co. Ltd., Yan’an, Shaanxi, 716000, China
² Changqing Downhole Technology Operation Company, CNPC Chuanqing Drilling Engineering Co.Ltd., Xi’an, Shaanxi, 710018, China
³ Shaanxi Key Laboratory of Safety and Durability of Concrete Structures, XiJing University, Xi’an, Shaanxi, 710123, China

^* Corresponding author: 20190100@xijing.edu.cn

Abstract

In order to promote the rolling exploration and development of oil reservoirs in northern Shaanxi, a fine study of sedimentary facies in area A has been carried out. Using core and logging data, on the basis of identifying different levels of sequence interfaces and lake flooding, the Chang 2 Member in Area A was divided into two base level cycles, and a high-resolution sequence stratigraphic correlation was established. On the basis of core description, the analysis of single-well sedimentary facies, continuous-well sedimentary facies and planar sedimentary facies are carried out. It is believed that the Chang 2 member of the study area is a delta plain deposit, dominated by distributary channels, inter-distributary depressions, and natural dike microfacies. There are two to three main rivers in the study area. Both the vertical and the plane show that the length of Chang 2₂ sand bodies is more developed than the length of Chang 2₁ sand bodies. Among the three small layers of Chang 2₂, Chang 2₂¹ sand body is relatively well developed, and the channel width and thickness are large, making it the most favorable reservoir.