RESEARCH ON SEDIMENTARY FACIES OF THE CHANG-8 MEMBER OF THE YANCHANG FORMATION IN ZHENJING OILFIELD,ORDOS BASIN

The Chang-8 Member of the Yanchang Formation in south of Ordos Basin Zhenyuan—Jingchuan area have been lots of years data of accumulate and depth study,On the base of core observation,logging data and the studied results of former geologists,and through statistical analysis of petrophysical data and logging data,Then,use logging curves to classify logging facies based on the lithology-electric property relation.According to the upper research results,the sedimentary facies is determined to be the front-delta deposition of braided river delta deposits,and five microfacies types are recognized including subaqueous distributary channel,subaqueous natural barrier,subsea crevass-splay,mouth-bar,subaqueous interdistributary embayment.The depositional characterisytics and the structure of microfacies types in sections are discussed,and the lateral distribution of the sedimental facies and the sedimentation model are predicted.