Sedimentary microfacies characteristic of Chang2 reservoir of Sai431 wellblock in Ansai oilfield

Based on geologic background,combining with log- ging data of Chang2 reservoir of Sat431 wellblock of Ansai oilfield,a comprehensive study on the marks of sedimen- tary facies has been made up,core's color,rock types, sedimentary structures,biological features and grain size distribution included,and it is considered to be a mean- dering river delta plain subfacies which can be further di- vided into distributary channel microfacies,point bar mi- crofaeies,natural levee microfacies,flood-plain splay microfacies and interdistribution bay microfacies et al.Af- ter the analysis of different sedimentation features,sedi- mentary models in Chang2 reservoir are established.Ma- jor reservoir sandstone bodies include distributary channel and point bar microfacies.Good connectivity and physical property and poor inhomogeneity are identified along the parallel direction of sediment supply,and vice versa along the vertical direction of sediment supply.