波斯湾盆地新生界油气成藏组合地质特征及成藏模式

Geological Characteristics and Hydrocarbon Accumulation Model for Cenozoic Play in Persian Gulf Basin

波斯湾盆地新生界主要有5套油气成藏组合,其中阿斯马里组—加奇萨兰组成藏组合是最重要的油气成藏组合之一。通过对该成藏组合古地理演化、烃源岩、储集层、盖层、成藏过程和模式的分析认为,沉积于低能闭塞环境的中白垩统卡兹杜米组烃源岩,在上新世早期达到排烃高峰,生成的油气通过相关的裂缝系统垂向运移到渐新统-下中新统阿斯马里组石灰岩裂隙型储集层中;中新统加奇萨兰组为渐新统-下中新统阿斯马里组提供有效的区域盖层;油气在侧向挤压形成的构造圈闭中聚集成藏。优质的烃源岩、储集物性良好的储集层、沟通烃源岩与储集层的裂缝、有效的区域和局部盖层、油气生成期与构造活动、裂缝及圈闭形成期的良好匹配等是油气富集的主控因素。

There are five hydrocarbon accumulation plays in Cenozoic in Persian Gulf basin,of which the Asmari-Gachsaran play is the most important one.The paleogeography evolution,hydrocarbon source rocks,reservoir rocks,cap rocks and hydrocarbon accumulation process are studied,showing that the Middle Cretaceous hydrocarbon source rock of Kazhdumi formation was deposited in low energy and euxinit environment,and reached hydrocarbon generating/expulsion peak in Early Pliocene.Oil and gas migrated vertically along fractures and finally accumulated in Oligocene-Lower Miocene Asmari fractured limestone reservoir.The Miocene Gachsaran formation provided an effective regional seal for the Oligocene-Lower Miocene Asmari reservoir.The oil and gas accumulation occurred in structural trap formed by lateral compression.The high quality source rocks,favorable reservoir rocks,fractures connecting the source rocks with reservoirs,effective regional/local seals,and the good matching between hydrocarbon generating peak and tectonic activity,fracture,trap forming time are the key of hydrocarbon enrichment in Asmari-Gachsaran play.