鄂尔多斯盆地姬塬地区长8 油层组岩性油藏成藏机理研究

致密砂岩型岩性油藏的成藏机理是制约鄂尔多斯盆地延长组深入勘探的核心问题。综合利用储层岩石学、油气/油藏地球化学及盆地数值模拟领域中先进的技术与研究方法，从有效烃源岩出发，以压力场演化及其控制的流体动力学和运动学过程为核心，探讨了姬塬地区延长组长8 油层组岩性油藏的成藏机理。结果表明，长8 油层组原油主要来源于长7 段及长8 段的生烃有机质，油藏存在2 期充注过程，以早白垩世晚期（105～95 Ma）充注为主。210 Ma 以来，压力场经历了早期升高→中期迅速升高→后期降低的演化过程。早白垩世大量生烃及中晚燕山期构造挤压是超压发育的主要成因机制，受强超压控制，长8油层组岩性油藏呈现近源充注、隐性输导、快速聚集的成藏模式。

Hydrocarbon accumulation mechanism of lithologic reservoir of Chang 8 member in Jiyuan area, Ordos Basin

The accumulation mechanism of lithologic reservoir in tight sandstone gradually becomes the main difficulties and frontier areas for exploration arrangement in Yanchang Formation of Ordos Basin. Based on the analysis of potential source rock and oil-to-source correlation, combined with pressure field evolution, fluid dynamics and fluid kinematics, the accumulation mechanism of lithologic reservoir of Chang 8 member is discussed by using petrology and advanced techniques used in geochemistry and basin numerical simulation. The results show that the hydrocarbon of Chang 8 member mainly originated from the generating organic matter in Chang 7 and Chang 8 member of Yanchang Formation. Reservoirs of Chang 8 member take on two-stage charging processes, and the main charging time is in late Early Cretaceous （105-95 Ma）. Since 210 Ma, the pressure field evaluation experienced three processes： early increase, middle quick increase and late reduce. Moreover, the broad hydrocarbon generation in Early Cretaceous and the tectonic compression in Middle-Late Yanshanian are the main formation mechanism for overpressure. The accumulation model of lithologic reservoir in Chang 8 member presents near-source charging, latent conduit and rapid accumulation.