关键词: 松辽盆地北部, 岩性油气藏, 形成条件, 分布规律

Abstract: Against the sedimentary background of fluvial and delta sedimentary systems in large depression-type lake basin, Songliao Basin certainly has the geological conditions for forming lithologic oil reservoirs in large areas. Vertically, the lifting and descending of datum level in various periods causes big difference in allowable space in the different stages. Therefore, there is a certain difference in the types of developed sandbodies. Meanwhile, the migration and accumulation conditions and distribution law of those lithologic oil reservoir of each assemblage are quite different owing to the difference in the buried depth of reservoirs and locations of hydrocarbon source rock. On the plane, the types of lithologic oil reservoirs are controlled by structural positions and maturity of sandstone. The lithologic oil reservoirs are formed mainly in the frontal facies zone outside the delta in the depression. The surrounding areas of the depression are the main locations for development of various subtle oil and gas reservoirs. Guided by the high-resolution sequence stratigraphy, the detailed geological study was made on Putaohua oil layer of Yaojia Formation in the northern part of Songliao Basin in the light of the actual conditions of the sandy-shale thin interbedded lithologic oil reservoir in the frontal facies zone of the delta. It is found that the oil and gas reservoirs are distributed in belts. Therefore, distribution of oil and gas reservoirs is divided into the belt for structural oil and gas reservoirs as well as the belt for structural-lithologic oil and gas reservoirs and lithologic oil and gas reservoirs, clarifying the orientation for exploration of subtle oil and gas reservoirs.