Reservoir Sedimentol ogy of Braided River Sandbodies—A case study of the outcrop in Zhang jiakou Region

Key words: 
• braided river /
• reservoir sedimentology /
• bounding surface /
• lithofacies /
• reservoir model

Abstract: From the view of reservoir sedimentology,this paper analyzed the formation of braided river sandbodiesin the Zhangjiakou region,identified three-order bounding surfaces and six types of lithofacies，and discussedthe influence of sedimentation and diagenesis on reservoir properties. It was concluded that sedimentation is adominant factor controlling reservoir properties, and the influence of diagenesis on reservoir properties is af-fected by sedimentation. Middle grain size and mud content have great influence on reservoir properties. theinfluence of cements on porosity is greater than that on permeability. It was also showed that there is a closerelationship between lithofacies and reservoir properties,lithofacies formed in high energy environment usuallyare good reservoirs. The control of bounding surface on reservoirs lies in the following:the first order bound-ing surface controls the geometry and extension of sandbodies, the second one controls the heterogeneity ofsandbodies,and the third one controls the distribution of favorable reservoirs. Finally,a 1-D and a 2-D geolog-ical reservoir models were established,these models would be instructive for oil production.