| The exploration and development of super-low permeability reservoirs occupies an important position in petroleum industry of China. As the special geological conditions, the characteristics of the vadose law, the development pattern and the remaining oil distribution are different from the conventional reservoir. Therefore, it has an important theoretical and practical significance on the fine description of super-low permeability reservoirs and the study of remaining oil distribution.Chuankou oilfield is located in the southeast of Ordos basin, characterised with a gentle and simple structure and a strong reservoir heterogeneity, is a typical super-low permeability oilfield. This oilfield is in middle and late periods, leds to the loss of formation energy, reducing of single-well production, depleting seriously of oil production, raising rapidly of water yield and the complexity of remaining oil distribution, because oil production was used to rely on natural energy in the early period, and formation energy didn't complemented simultaneously.The distribution scale of remaining oil is researched by fine reservoir description in Chang4+5reservoirs of Chuan46block in southern Chuankou oilfield. Based on the deposition and reservoir analysis, the reservoir flow unit has been divided and its horizontal distribution has been forecasted. The three dimensional geological model of reservoir porosity, permeability and oil saturation was established by using the advanced international modeling software. The remaining oil distribution was forecasted by reservoir numerical simulation method. The current remaining oil distribution was predicted by way of analyzing the macroscopic and microscopic controlling factors of the remaining oil. Thus, these methods establish a solid theoretical foundation for highly effective development of super-low permeability reservoirs.It is showed that reservoir micro-structure plays a particular role in the controlling of oil-water differentiation and remaining oil distribution. There was strong heterogeneity in reservoirs as a result of sedimentary facies distribution and diagenesis. The flow units were divided into four types, in which type B flow unit was the main type in this area and distributed the region of the river channel, type A and C flow units were relatively less, type D flow unit was mainly distributed region of interdistributory bay and formed flow barrier.It is indicated from analysis on Chuan46block that the variation function analysis techniques of different reservoir structure feature, argillaceous content parameters by the log interpreting, the three dimensional reservoir lithofacies models by application of kriging technique, the quantitative and visualization technology of reservoir characteristics, are also suitable for low permeability reservoir description and simulation. Then the lithofacies, porosity and permeability and oil saturation model of Chang4+52-2of Chuan46block were established. The test result shows that requirement of correct statement reservoir characteristics can be achieved by this three dimensional geological models.The degree of reserves development in small layers and remaining oil distribution were researched synthetically in study area, the development degree in the plane of Chang4+52-2reserves is obviously different among different areas, because of influence of relations between well control and injection-production, reservoir heterogeneity and flow unit, sand body fine construction and reservoir thickness, reservoir fracture trend. There are still a lot of remaining oil, five favorable areas of remaining oil distribution are predicted. The distribution of remaining oil distribution is not only controlled by macroscopic factors, including sedimentary facies, reservoir heterogeneity, flow unit and well spacing distribution, but also controlled microscopicly by the heterogeneity of pore structure, flow characteristics of two phase flow and distribution of fluid field in process of water displacing oil.
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