Study On Beach Bar Reservoir Characteristics Of The Upper 4th Member Of Shahejie Formation In Chundong New Area

The sedimentary subfaces of the reservoir of the upper 4th Member of Shahejie Formation in Chundong new area is beach bar. The beach bar sandstone is buried very deep, and its lithological constitution is complex. It is characterized by interbedded thin layers and low permeability. The reservoir has poor physical properties, and because of the strong heterogeneity and the complexity of oil distribution, the exploration and development is very difficult. At present, the knowledge of the reservoir characteristics of this area is imprecise which restricted the later development and adjustment of the oilfield. It is the urgent time to start with the basic geological and dynamic development data to carry out the fine detailed reservoir characteristic research and comprehensive evaluation.On the basis of informed research, a series of intensive study has been conducted on the sedimentary subfaces and reservoir heterogeneity at a full use of the seismic data, drill core date, logging data, well and analysis and assay data, production dynamic and production testing information, which directs the classification and evaluation of the reservoir. The upper 4th Member of Shahejie Formation has been divided into 5 sands groups and 20 single layers, the sand layers are thin but have good continuity. The reservoir mainly develops clastic beach bar, carbonate beach bar and and shallow lake mud microfacies, and the clastic beach bar is divided into beach host, bar side, beach ridge and beach mat microfacies. The sedimentary microfacies has been revealed from vertical and horizontal aspects, the beach mat is widely developed, and the clastic beach bar mainly develops in the first to third sands groups and the carbonate beach sands groups mainly develops in the fourth and fifth sands groups.The lithology of reservoir is feldspar siltstone and marlstone that has low compositional maturity and medium construction maturity. The reserving space is mainly inter-grain pore and corrosion holes. The main diagenesis types are compaction, carbonate cementation, quartz overgrowth and dissolution. The reservoir has strong intraformational heterogeneity, interlayer heterogeneity and plane heterogeneity, and the reservoir heterogeneity is mainly dominated by sedimentation, diagenesis and structure. The standard of the reservoir synthetic classifying evaluation is established by comprehensive consideration of the sandstone thickness, effective thickness, porosity, permeability, lithology, oiliness, microfacies types and structural location. The reservoir can be divided into three types according to the evaluation result, and the Ⅰ and Ⅱ types are the main goal of the later development.