川西南地区二叠系火山岩储层特征

利用野外观测、钻录井、薄片、常规测井等资料,综合分析川西南地区二叠系火山岩储层的特征及主控因素。结果表明:区内火山岩储层主要发育在火山熔岩和火山碎屑岩之中。火山熔岩的储集空间以气孔等原生孔和构造缝为主,孔隙度和渗透率较低,孔渗相关性差,为孔隙–裂缝型储层;火山碎屑岩的储集空间以气孔等原生孔和粒间扩大孔、微孔等次生孔隙为主,可见冷凝收缩缝,火山角砾岩和凝灰岩物性均优于火山熔岩,但孔渗相关性一般;熔结凝灰岩有较好的孔隙度和孔渗相关性,为孔隙型储层,储集性能优良。有利的岩性岩相是储层发育的基础,爆发相是储层发育最有利的相带;地表的风化(淋滤、溶蚀)作用对储层进行改造,次生溶蚀孔隙是最主要的储集空间;构造作用是储层形成的重要条件,构造作用形成的裂缝作为储集空间的同时也连通了火山岩中部分原生的孤立孔隙。

Characteristics of Permian volcanic reservoirs in southwest Sichuan

The characteristics and main controlling factors of Permian volcanic reservoirs in southwest Sichuan are analyzed by means of field observation, drilling and logging data analysis, thin section identification, conventional logging and imaging logging data. The results show the volcanic reservoirs are mainly developed in the volcanic lavas and pyroclastic rocks. The reservoir space of the volcanic lavas is mainly composed of primary pores and structural joints, with low porosity and permeability and poor correlation of porosity and permeability. The reservoir space of the pyroclastic rock is mainly composed of primary pores, such as pores, and secondary pores, such as inter-granular enlarged pores and micro-pores. It can be seen that the condensate contraction joints, volcanic Breccia and Tuff are superior to volcanic lavas in physical properties, but the correlation between porosity and permeability is relatively general, the ignimbrite has good porosity and permeability correlation, and it is a porous reservoir with good reservoir performance. Favorable lithology and lithofacies are the basis of reservoir development, and explosive facies is the most favorable facies belt for reservoir development. The weathering(leaching and dissolution) of the surface transforms the reservoir, and the secondary dissolution pore is the main reservoir space. Tectonism is an important condition for the formation of reservoirs. As a reservoir space, the fractures formed by tectonism improve the primary isolated pores in volcanic rocks.