南襄盆地泌阳凹陷南部陡坡带油气成藏过程分析

烃源岩及构造演化历史控制了南襄盆地泌阳凹陷南部陡坡带油气的成藏与演化。古近系核桃园组核二段沉积时期—核一段沉积末期,油气小规模充注,形成早期古油藏;廖庄组沉积末期,构造抬升,油气大规模充注,形成中期南部陡坡油气聚集带,是南部陡坡带核三段原生油气藏的主要成藏期;新近系凤凰镇组沉积末期,晚喜马拉雅期构造运动导致部分早、中期古油藏遭受破坏与调整,是形成浅层次生油气藏的时期。总体而言,早、中期隆起背景控制南部陡坡带的油气富集,晚期构造调整决定南部陡坡带的油气分布。南部陡坡带浅层系发育的小规模隆起构造、大型隆起构造翼部发育的岩性圈闭及基岩裂缝型圈闭,是下一步油气勘探值得重视的目标。

HYDROCARBON ACCUMULATION PROCESS IN SOUTH STEEP SLOPE,BIYANG SAG,NANXIANG BASIN

Evolution history of hydrocarbon source rocks and tectonics dominates hydrocarbon accumulation in the south steep slope of the Biyang Sag,the Nanxiang Basin.In the slope,early paleo-reservoirs are formed by small-scale hydrocarbon charging during the late Eh1-Eh2 of Paleogene.The middle key reservoirs of Eh3 are formed by relatively larger volume of hydrocarbon charging during the late El uplifting stage of early Paleogene.The shallow secondary oil and gas reservoirs are formed by destruction and redistribution of paleo-reservoirs due to late Himalayan tectonic movement at late Neogene.In ge-neral,it is the early and middle uplifts during late Eh1-Eh2 of Paleogene which control oil and gas accumulation in the south steep slope,while the structural adjustment in the late stage dominates the pre-sent distribution of oil and gas.The small-sized uplifts developed in shallow formations,the lithologic traps developed in flanks of large-sized uplifts as well as the fracture traps developed in bedrock are important targets for future exploration.