不同岩性储层的微观孔隙特征

油气藏储层的微观孔隙结构特征与分布规律决定了储层的储集能力、渗流能力以及渗流机理与渗流规律,储层岩性不同其对应的微观孔隙结构特征与分布规律一般也存在较大的差别,储层的开发动态其实就是微观孔隙渗流特征的宏观体现。通过运用压汞实验与核磁共振实验测试技术,重点研究了低渗砂岩、火山岩和碳酸盐岩储层的微观孔隙大小、数量、结构和分布规律及其与宏观孔、渗物性参数的对应关系。研究结果显示3种不同岩性储层的微观孔喉分布规律差异明显:低渗砂岩储层孔喉发育、数量多,大孔喉占比多,连通性好,分布均匀,是典型的中孔-中喉型储层;火山岩储层孔喉更加发育、数量更多,大孔喉占比少,连通性较好,但分布不均,是典型的小孔-细喉型储层;碳酸盐岩基质储层孔喉极不发育、数量很少,且集中分布在大、中孔区间,含有少量溶蚀孔洞,连通性差,是典型的大孔-细喉型储层。该研究成果可以合理解释不同岩性储层的储渗能力及其对应的气井生产动态与开发效果,对于油气藏合理有效开发具有重要的理论指导与实践意义。

Microscopic pore characteristics of different lithological reservoirs

The reserving capacity as well as the porous flow ability, mechanism and laws are determined by the micro-pore structure characteristics and distribution laws of hydrocarbon reservoirs. There is generally a large difference in the micro-pore structure characteristics and distribution laws due to different reservoir lithologies. The reservoir development dynamic state is actually the macroscopic reflection of micro-pore porous flow characteristics. Mercury injection experiment and nuclear magnetic resonance testing technology are applied to study the micro-pore size, quantity, structure and distribution laws of low-permeability sandstone, volcanic rock and carbonate reservoirs as well as their corresponding relation with macro porosity-permeability physical parameters. Research results indicate significant differences exist in micro-pore-throat distribution laws of three different lithological reservoirs. The low-permeability sandstone reservoirs are characterized by the wide development of pore-throats and a large proportion of pore-throats with good connectivity and even distribution, belonging to typical medium pore-throat reservoirs. Volcanic reservoirs are characterized by the better and wider development of pore-throats and a small proportion of pore-throats with good connectivity but uneven distribution, belonging to typical small pore-throat reservoirs. Carbonate reservoirs are characterized by an extremely small number of pore-throats mainly distributed in the large and medium pores with a small number of dissolution pores and poor connectivity, belonging to typical large pore-throat reservoirs. These research results could reasonably explain the reserving and permeability capacity of different lithological reservoirs as well as the corresponding gas well production performance and development achievements, which has theoretical guidance and practical significance to rational and effective development of oil-gas reservoirs.