准噶尔盆地西北缘二叠系储层特征及分类

CHARACTERISTICS AND CLASSIFICATION OF PERMIAN RESERVOIRS IN NORTHWESTERN MARGIN OF JUNGGAR BASIN

准噶尔盆地西北缘二叠系储层包括了砂砾岩、火山碎屑岩和火山岩两大类 ,总体上属于低 中孔渗储层 ,但孔隙度、渗透率的分布较为分散 ,显示了二叠系储层物性的非均质特征。碎屑岩储层中主要的储集空间为剩余粒间孔隙以及在此基础上扩大溶蚀的孔隙 ;火山岩储层中则以火山岩基质溶蚀孔为主 ,构造缝、溶蚀缝次之。次生溶蚀孔隙是形成高质量储层的重要组成部分。研究发现 ,次生孔隙发育带与地层沉积间断密切相关。通过对储层物性和孔隙结构等 8个参数变量采用Q型因子分析后 ,确定了孔隙度下限为 9 ,碎屑岩储层的渗透率下限为 0 2× 10 -3 μm2 ,火山岩储层的渗透率下限为 0 2× 10 -3 μm2 。以此为标准可将二叠系碎屑岩储层和火山岩储层划分为 4类。

Permian reservoirs in northwestern margin of Junggar Basin include sandstone,conglomerate,volcanic clastic rock and volcanic rock with low-medium porosity and permeability. The disperse distribution of porosity and permeability reveals the heterogeneity of the reservoir physical property. The pore spaces are mainly residual intergranular porosity, dissolution porosity in clastic rock reservoir,dissolution matrix porosity and fractures in volcanic reservoirs. Secondary dissolution porosity plays the key role of reservoir quality. The development of secondary porosity is closely related to depositional hiatus.Based on Q-mode fator analysis of eight variables of rock physical property and pore configuration, it is suggested that the lower limit of porosity is 90/0; the lower limit of permeability of clastic rocks is 0.2×10 -3 μm;the lower limit of the permeability of volcanic rocks is 0.2×10 -3 μm.The Permian reservoirs could be divided into four types accordingly.