Sedimentary Facies Research And Favorable Regions Of Es₄ Member In The Wangjiagang Area Of Dongying Sag

Wangjiagang area is located in the southeast slope of the Dongying sag,. Since the oilfield in the area has been found in 1971, after 34 years prospecting and developing, it has become the important oilfield. Because of the strong heterogeneity of the Es4 Member reservoir and the complexity of oil distribution, the cost of exploration is very high. In order to reducing the cost of the exploration and development, finding out the rule of the oil and gas distribution, providing the credibility geology gist for the further exploration and development, it is necessary to research the sedimentary facies and main target district.Based on the high resolution sequence stratigraphy and the sedlmentology theory, by the describing of cores and the analyzing of well log data, the paper establish the Es4 Member stratigraphic framework in the first time in the Wangjiagang area.Through the analysis of petrology characteristics and individual well section of sedimentary facies of twelve core holes, main facies types and its features of Es4 Member in the Wangjiagang area are summarized on the basis of sedimentary background of region. The sedimentary facies of Es4 Member in the Wangjiagang area is beach-bar. By the analysis and contrast of plans of sedimentary facies and isopach maps of sandstone, the planar characteristics of distribution of sedimentary facies and sand bodies are elaborated. The integrated study of heavy mineral and sedimentary facies distribution has disclosed that the detritus are derived chiefly from the Guangrao heave.The sandstones can be classified as compositionally immature lithic arkose. The main diagenetic minerals of the sandstones include authigenetic clay minerals, calcite and dolomite cement, quartz overgrowth The sandstone rifely endured mid-high compaction. Cementation was complicated and multiple and solution was developed.Based on diagenetic events related to temperature, the reservoir diagenetic stages can beclassified into A-substage of later diagenesis. The reservoir quality is controlled mostly by sedimentary microfacies and diagenesis. The bar sandbodies are commonly of high porosity and permeability, whereas the beach may be of low petrophysical properties.The path and time of hydrocarbon migration are studied based on the study of effective source rocks, fault structure and reservoir deposit system, which shows that Chenguanzhuang-wangjiagang Fault and Bamianhe Fault and other minor faults are the main paths between source rock and sand reservoir in traps, and beach-bar sandstones are another important kind of migration path. The formation model of oil pools in this area was established. According to the results of this study, the favorable regions for petroleum exploration are predicted.