中东扎格罗斯盆地构造演化与油气分布

Structural characteristics and main controlling factors on petroleum accumulation in Zagros Basin,Middle East

扎格罗斯盆地是中东地区重要的含油气盆地之一,已探明储量巨大。通过区域构造演化、盆地构造划分、油气分布特征和油气成藏主控因素研究,认为扎格罗斯盆地由被动陆缘盆地演化而成现今的前陆盆地,经历了早古生代克拉通—弧后伸展阶段、晚古生代弧后伸展阶段、中生代被动陆缘盆地阶段和晚中生代—新生代前陆盆地演化阶段。扎格罗斯山前缘断裂带和高扎格罗斯断裂带将盆地自西南向东北划分为前渊带、简单褶皱带和山前冲断带等3个构造带。扎格罗斯盆地前渊带以油田为主,简单褶皱带以气田为主,山前冲断带挤压构造变形强烈,油气难以保存。下白垩统Kazhdumi组烃源岩为中—新生界储层的主要油源,志留系Gahkum组泥页岩为古生界储层的主要气源;新生界碳酸盐岩为主力储层,其次是白垩系Sarvak组和上二叠统Dalan组碳酸盐岩;前渊带以蒸发岩和泥页岩盖层为主,简单褶皱带则以泥页岩盖层为主。背斜构造和盖层类型为油气成藏的主要控制因素。

Zagros Basin is one of the most important basins in the Middle East with the giant oil and gas reserves.It is indicated by regional tectonic and sedimentary evolution,basin structural division,petroleum distribution characteristics and main controlling factors of petroleum accumulation.It has experienced four major phases which are early Paleozoic intra-Cratonic pulling apart basin and platform margin basin,Late Paleozoic platform margin basin,Mesozoic passive continental margin basin and Cenozoic foreland basin.The Zagros Mountain Front Fault and High Zagros Fault divided the basin into foredeep zone,simple fold zone and Zagros thrust fault zone from southwest to northeast.The oil fields are mainly located in the foredeep zone,while the gas fields are mainly in the simple fold zone and few fields are in the Zagros thrust fault zone.The Lower Cretaceous Kazhdumi Formation mudstone is the main source rock for the Mesozoic and Cenozoic reservoirs and the Silurian Gahkum Formation mudstone is main source rock for the Paleozoic reservoirs.The Cenozoic carbonate is main reservoir followed by the Cretaceous Sarvak and Upper Permian Dalan carbonate.The evaporate and mudstone are the main seal in the foredeep zone,and the mudstone is the main seal in the simple anticline zone.The anticline structure and the seal type is the main controlling factor for the petroleum accumulation.