This paper aims at describing the reservoir microcosmic heterogeneity characteristics and analyzing its major control factors, which is very important to this type reservoir’s predication and development. Based on the comprehensive research of the cores, thin slices, SEM, mercury-injection data, and predecessors’ research outcome of Suderte area in Hailar Basin, the authors come to the conclusion that, compared with normal sandstone, tuffaceous sandstone has more pore types and more complicated pore texture because of pyroclastics composition mixing, and has severely micro-cosmic heterogeneity correspondingly. Sedimentary microfacies types and tuffaceous origin of sandstone are the fundamental factors affected reservoir micro-cosmic heterogeneity because they decided the lithologic composition, diagenesis type and degree. With different relative content among crystal, shard and lithic in pyroclastic grain, or different relative content between pyroclastic grain and ash matrix, sandstone has different pore texture and physical property characteristics.
