Factors for controlling lithologic oil pool formation and exploration prospects in southern Songliao Basin

There are three main controlling factors for forming a large area of lithologic oil pool in the southern Songliao Basin.The sandstone and mudstone were developed alternatively in the delta front belts and controlled the overall oil-bearing area.The north-north-west directional faults vertical to the sandstone elongation direction provided the effective lateral plugging condition,whereas many lacustrine mudstones formed during water invasion stage provided the good direct cap-rocks.Those are the essential conditions for oil-bearing area.Three delta front belts in west,south-west and south-east directions will be the main exploration targets for finding wide-area lithologic oil pools and also represent the actual domain to obtain petroleum reserves in recent period.