晚古生代右江盆地生物礁储层特征研究

Study on reservoir characteristics of the Late Paleozoic reef in Youjiang basin, China

由于海平面的变化,右江盆地发育了泥盆纪和中晚二叠世两个重要的成礁期,生物礁广泛分布在桂西、桂南、黔南、桂中、滇东等地区陆棚的台地边缘、孤立碳酸盐台地上。显微照片和扫描电镜显示礁灰岩储集空间主要包括孔隙、裂缝和溶洞。孔隙类型有粒内溶孔、骨架孔、粒间孔、遮蔽孔、溶孔、缝合线伴生溶孔和基质微孔隙,而以晶间溶孔、晶间孔及非组构控制的溶蚀孔、洞、缝为主。储层类型为裂缝孔隙型和孔隙型,厚度5～55m,岩性为生物礁和生物滩相的生物灰岩或生物碎屑灰岩,残余生屑粉-细晶白云岩。

Two stages of reef growth are recognized in Devonian, Middle and Late Permian in Youjiang basin, respectively. Reefs are widespread and exposed in west Guangxi, south Guangxi, south Guizhou, middle Guangxi, east Yunnan, and have ever been distributed along platform margins or on isolated platform. Micrograph and scanning electronic microscope show that reservoir space is of pore, fissure and solution hollow in reefal limestone. The interstice types are distinguished as intragranular corroded hollow, frame pore, intergranular pore, corroded hollow, corroded hollow associated with stylolite and micropore in matrix. Intercrystalline pore, intercrystalline corroded hollow, and corroded pore, hollow fissure, controlled by non-fabric are the main types. It is suggested that the reservoir type can be classified as fissure-pore type and pore type, and the reservoir thickenss ranges from 5 to 55 m. Reservoir rocks are dominated by either boundstone or bioclastic limestone, or biolclastic dolomicrite, or cryptalline dolomite. For the later two dolomites, textures are often diagenetically altered.