Oil Geological Characteristics and Exploration Trend of Triassic Lower Group in Xiasiwan Area of Ordos Basin

Triassic upper group of the Yanchang Formation in Xiasiwan oilfield,as the next section of the main reservoir,after decades of exploration and development,its reserve resources become increasingly inadequate.By analysis on oil-bearing section in the Xiasiwan area in recent years,we found that the lower group of Triassic Yanchang Formation Chang 7-Chang10 segments showed good oil and gas resources.By discussing the sedimentary facies,sand body shape,reservoir-cap,structural features,lithological assemblage of the lower group of Yanchang Formation under section Chang 7-8,we can find layer system replacement resources for the steady development of Xiasiwan oilfield.