Study Of Development Geology Of Chang-8 Reservoir In Chi223 Well Block Of Ordos Basin

With an area of about 24.5 km2, Chi223 well block, structurally belonging to the northwest of Ordos Basin, is located in Dingbian County, Shaanxi Province. Since the production, through the rolling exploration and development, the oil field with good exploration and development potential has constantly expanded the scale. At present, the development law, reservoir characteristics and other aspects of reservoir still need to further deepen the understanding in the study area. This paper makes full use of geological, well-logging, core and laboratory data, as the research focus in reservoir and oil reservoir characteristics of Chi223 block, analyzing reservoir enrichment regularity and the main control factors of hydrocarbon accumulation.The achievement and understanding are as follows:(1) Chang 8 oil layer group is divided into Chang811, Chang812, Chang821 and Chang822 from up to down in the study area, The sequence framework of each small layer is stable. The layer Chang822 is 21~25m thick. The layer Chang821 is 19~22m thick. The layer Chang812 is 18~23m thick. The layer Chang811 is 21~25m thick.(2) Using core and log data, the study area was identified as delta front sedimentary sub facies., and it was further divided into underwater distributary channel, distributary bay, nature levee and mouth bar microfacies, mainly is underwater distributary channel microfacies, The underwater distributary channel is mainly branch or strip shaped, with the sedimentary characteristics of constructive fluvial delta(3) Through analyzing core and thin section data, the paper has cleared about the reservoir lithology, porosity and permeability characteristics, and specially studied the reservoir heterogeneity. The reservoir layer and interlayer heterogeneity is weak and the plane heterogeneity is relatively strong.(4) The reservoir forming conditions and main controlling factors are analyzed. It is pointed out that the Chang8 reservoir is lithologic oil reservoir. The barriers on the top of the reservoir have adverse effects on oil accumulation.(5) According to the oil thickness, pore and permeability, oil content and initial oil production, the reservoir of used area is divided into three levels, and deploy 1 extension rolling development zone, 2 favorable areas in Chang 811 and Chang 822 in the unused areas.