准噶尔盆地腹部中浅层远源、次生油气藏成藏过程及主控因素

通过分析准噶尔盆地腹部中浅层侏罗?白垩系油气储集层中烃类包裹体的均一温度、地层埋藏史?热演化史、成藏期构造、已知油藏和地球化学运移指标, 探讨油气成藏期次、有效输导体系、运聚过程和圈闭遮挡条件, 进一步揭示腹部地区中浅层远源、次生油气藏的动态成藏过程。结果表明, 侏罗?白垩系存在两期成藏, 分别为白垩纪形成的原生油气藏和古近纪末至今形成的次生油气藏, 两类油气藏在腹部地区均广泛分布。断裂?砂体?区域不整合面对远源、次生油气藏的动态运聚起着立体输导作用。原生油气藏的形成受成藏期古构造的影响, 后期的古构造变形使得原生油气藏发生破坏调整, 油气向北运移, 遇到遮挡形成次生油气藏。油气在运移路径上的遮挡条件决定着油气藏类型, 目前在腹部地区发现的油气藏主要为平缓背斜油气藏、断块油气藏和岩性地层油气藏。

Accumulation Process and Control Factors of Jurassic-Cretaceous Distant-Source and Secondary-Filled Reservoirs in the Hinterland of Junggar Basin

Homogenization temperature of fluid inclusions, stratigraphic burial-thermal history, paeleostructure of accumulation period, known reservoirs and geochemical index are analyzed. Hydrocarbon accumulation periods, hydrocarbon transport system, trap-forming conditions of the Jurassic-Cretaceous in the hinterland of Junggar Basin are discussed. Thus, the dynamic accumulation process of the distant sourced, secondary-accumulated reservoirs is revealed. Results show that there are two periods of oil and gas charging in the Jurassic and cretaceous reservoirs in the hinterland of Junggar Basin, which are primary reservoirs formed in the early Cretaceous and secondary-filled reservoirs formed in the late paleogene till now. Both the primary reservoirs and sencondary accumulated reservoirs are widely spread in the hinterland area. Faults-sand bodies-unconformities act as three dimensional transporting systems for hydrocarbon migration and accumulation. The formation of primary reservoirs is controlled by paleostructure of accumulation period. During the later dissolution of paleostructure, primary reservoirs are destroyed and oil and gas migrate towards the north. Reservoirs types are decided by trap conditions on the migration pathways. At present, low-amplitude anticline, fault block and litho-stratigraphic reservoirs are the most discovered.