轮南潜山奥陶系碳酸盐岩储层裂缝发育特征

Feature of fracture development in Ordovician carbonate reservoir of Lunnan burial hill

通过研究油气成藏机理 ,分析碳酸盐岩裂缝发育特征 ,表明轮南潜山构造致密的碳酸盐岩储层基质孔隙度低 ,渗透性差 ,很难提供良好的储集空间 ,但裂缝的发育可以改善碳酸盐岩的储集条件 .根据岩心观察 ,轮南潜山奥陶系裂缝十分发育 ,主要分布在潜山顶面以下的风化壳带内 ,包括构造缝、溶蚀缝、成岩缝、风化缝等类型 ,以构造缝为主 ;裂缝产状特征主要表现为直立的或高角度斜裂缝发育 ,走向上具有分带性 .裂缝的发育主要受构造活动及后期溶解作用的影响 ;轮南潜山裂缝的发育 ,改善了碳酸盐岩的储集条件 。

Compact carbonate reservoir is of low porosity and permeability, and it cannot provide effective storage and accumulation space. But the growth of fractures can improve its storage and accumulation conditions. Based on the core observation of 1207 samples from 26 wells in Lunnan area, it is held that Ordovician fractures develop well in Lunnan burial hill. The fractures mainly distribute in the weathering crust zone under the surface of the burial hill. The fractures can be classified as tectonic fractures, kluftdarren, diagenetic fractures and weathered fractures, etc., and of them, tectonic fractures dominate. The orientation of the fractures is mainly vertical or high-angle of dip. The distribution of the fractures is characterized by zonation. The growth of the fractures is mainly affected by multiphase tectonic activities and later dissolution. The fractures in Lunnan burial hill improve the storage and accumulation conditions of the carbonate rock and provide the pathways for hydrocarbon filtration.