Analysis on Basic Conditions and Main Control Factors of Accumulation in Eastern Area of Yishan Slope of Ordos Basin

The group of reservoir and cap-rock in Chang4+5 and Chang6 has good basic conditions of accumulation in eastern area of Yishan Slope of Ordos Basin, because it located up the high quality sources rocks (Chang7) and had a lot of hydrocarbon migrated from western areas. The reservoirs were the sand bodies formed in the distributary channels of delta plain and subaqueous distributary channels of delta front. The cap-rocks were the mudstones and compacted siltites formed in the floodplain and interdistributary areas.They composed lithologic traps. The types of petroleum reservoirs belong to lithologic hydrocarbon reservoir. The distribution of oil layers controlled by depositional microfacies and the excellent quality group of reservoir and cap-rock and migration conditions.