塔中地区奥陶系碳酸盐岩深部埋藏溶蚀作用研究

Deep Buried Dissolution of Ordovician Carbonates in Tazhong Area of Tarim Basin

以岩心和岩石薄片观察为基础,对塔中地区埋藏溶蚀作用的类型、发育特征、成因机理及其对储层形成的影响进行了分析。综合研究表明,塔中地区奥陶系碳酸盐岩发育多期次、不同规模的埋藏岩溶作用,主要包括有机酸溶蚀作用和热液溶蚀作用等。其中有机酸溶蚀作用主要以组构的非选择性溶蚀作用为特征,并且其形成的溶孔多被烃类充填,有机酸溶蚀作用构成了该区深部的第一高孔隙带。热液溶蚀作用以选择性溶蚀为特征,多沿断裂、裂缝等分布,发育有萤石、绿泥石、闪锌矿、高温石英、重晶石等热液矿物,热液流体多来自地壳深部,与深部岩浆活动有关,热液溶蚀作用形成了该区第二高孔隙带。

Based on the observation of cores and rock sections,a deep buried dissolution,the types of buried dissolutions,development features,genesis and factors of reservoir formation in Tazhong Area of Tarim Basin were comprehensively analysed.The study shows that buried dissolutions of Ordovician carbonate in Tazhong Area are developed at multi-stages and various scales,including organic acid dissolution and thermal dissolution.The organic acid dissolution is characterized by fabric non-selective dissolution,and most of dissolution pores are filled with hydrocarbon.Organic acid dissolution constitutes the first high-porosity zone in the deep area.The thermal dissolution is characterized by fabric selective dissolution,and the dissolution developed mainly along faults and fractures,and fluorite,chlorite,sphalerite,high-temperature quartz,barite and other hydrothermal minerals are developed.The hydrothermal fluid mostly comes from the deep crust,and has a relationship with the magmatic activity.The thermal dissolution constitutes the second high-porosity in this area.