The Study Of Reservoir Characteristics Of The Member C8 Of Yanchang Formation In Jiyuan Oilfield In Ordos Basin

Chang8 reservoir of JiYuan region in Ordos Basin is the delta front. The lithology of the reservoir almost belongs to fine sandstone and siltstone. Exploration and development in recent years reveal that the horizontal change of the sandstone is so big that comparison of sand is difficult and heterogeneity in layer and interlayers is so great that make the understanding of the reservoir distribution which is beneficial to the development not clear. Based on the feature of ultra-low permeability reservoirs and reservoir classification and evaluation, it will guide the development of the reservoir. Under the guidance of the theory of the high-resolution sequence stratigraphy and sedimentology, thesis emphasizes the affect of sequence stratigraphic framework controlling the distribution of sandstone reservoir. According to core and well logging data, establishing high-resolution sequence stratigraphic framework of chang8 reservoir in JiYuan region, analysing characteristics of sedimentary facies, equitimely comparing the sandstone, researching the heterogeneity of the reservoir. And combined with distribution and physical property of the reservoir, dividing flow units. Finally, based on the research above,comprehensive evaluating the reservoir, classifying the reservoir and guidling the development of the reservoir.Based on core and well logging data and refered to the theory of the high-resolution sequence stratigraphy and sedimentology, identifying the change of base level, establishing high-resolution sequence stratigraphic framework of Chang8 reservoir which was recognized 2 long-term cycles,3 middle-term cycles and 6 short-term cycles.Researching facies in the framwork combined with core and well log information. The study shows that Chang 8 is the delta front. The main microfacies are underwater distributary channel, underwater interdistributory. Mouth bar is barely developed.Based on the analysis of sequence stratigraphy and sedimentary facies, the show obtained macroscopic characteristics of the sand body distribution. Then under the control of distribution of sandstone, based on core assay data, combined with Log interpretation data, researching the heterogeneity in layer, interlayers,and on plane using frequency and density of mudstone, variation coefficient and sudden coefficient of permeability and so on. Under the control of distribution of sand,dividing flow unit of chang 8 referenced interwell flow index. Chang 8 is mainly divided into 3 types of flow unit.Based on the analysis above,combined with effective sand thickness, porosity, permeability, heterogeneity parameters, doing cluster analysis to classify the reservoir. Looking for different types of reservoirs corresponding to the deposition, micro lithology, and the log response of a variety of reservoirs and patterns of the different reservoirs.