关键词: 渤中坳陷, 热沉降, 中浅层油气藏, 油气聚集

Abstract: Several big oil-gas reservoirs,with reserves of 100 million tons more,have been discovered in the Upper Tertiary middle and shallow strata of Bozhong area in Bohai Bay since last five years, as a result,the area became the hot-point area followed with interest by domestic and abroad oil men. Bozhong area has different oil-gas accumulation characteristics from the adjacent onshore oil fields. Because of the latter thermal event and tectonic action,Bozhong area became the subsidence center and depo-center of the Bohai Bay Basin. There is better reservoir-seal formation which is superior to the adjacent oil field onshore,the latter fault action timing with the big scale hydrocarbon migration provided the favorable conditions for oil-gas migration and accumulation toward Upper Tertiary trap. Many kinds of reservoir-forming model created many kinds of oil-gas reservoir,two kinds of fault structural system and the tectonic framework of horst-graben interval are favorable of the oil-gas rich accumulation toward middle-shallow strata and uplift area. Therefore the Upper Tertiary middle and shallow strata are major exploration zone.

Key words: Bozhong Depression, thermal subsidence, middle-shallow strata reservoir, oil-gas accumulation