辫状河砂体储层沉积学研究──以张家口地区露头砂体为例

Reservoir Sedimentology of Braided River Sandbodies──A case study of the outcrop in Zhangjiakou Region

本文从储层沉积学的角度，对张家口地区辫状河砂体的成因进行了分析，划分了3级层次界面和6种岩石相类型，对沉积作用和成岩作用与储层物性的关系进行了探讨。指出沉积作用是影响砂体物性的主要因素，成岩作用对物性的改造受沉积作用控制。粒度中值和泥质含量与储层物性密切相关，胶结物对孔隙度的影响大于对渗透率的影响。研究表明，砂岩相与储层物性能建立起很好的对应关系，代表高能环境的砂岩相总是对应相对较好的储层物性；界面对储层的影响表现在：1级界面控制了砂体的几何形态和规模，2级界面控制了单砂体的宏观非均质性，3级界面控制了高孔、渗区的分布。最后建立了辫状河砂体的一维和二维储层地质模型，这将对油田的开发设计起指导作用。

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