新疆塔里木盆地塔中地区奥陶系古潜山型油气藏成藏条件

Genetic analysis of Ordovician oil & gas trap developed on top of buried carbonate karst hill, Central Tarim Basin, NW China

塔中古隆起的早海西期风化壳岩溶发育,是塔里木盆地寻找古生代海相碳酸盐岩岩溶型油气田的重要隆起区之一。本文研究了风化壳型岩溶的发育特征和控制因素,在烃源、生储盖和成藏条件分析基础上预测了奥陶系风化壳岩溶发育的有利区带,认为奥陶系岩溶储层与其上覆的石炭系泥岩可构成良好的储盖组合,油源断裂、不整合面、输导层与汇烃脊构成了复杂油气输导网络。本区潜山型油气藏成藏过程复杂、期次多,但喜山期构造调整是最终成藏的关键,中央断隆带和塔中隆起南斜坡是两个有利的勘探区带。

Owing to weathering during Hercynian exposition of the karst is well developed,Ordovician carbonate uplifts in central Tarim Basin are important buried hills containing oil & gas. We studied on the development features and controlling factors of weathering crust karst. Based on hydrocarbon source,association of source rock,reservoir rock and cap rock,and analysis of pool-forming process,the authors predicted the potential developing area of Ordovician karst,which provides good conditions for the subsequent reservoir-forming processes. Several necessary factors for constructing this kind of buried hill traps include faults cutting through source rocks,unconformity,fluid migration layer and local uplift. The present valid pools were mainly formed in the Himalayan stage. The authors tried to predict that the central fault-uplift zone and the south slope of the uplift in central Tarim Basin are two potential oil & gas rich areas.