Reservoir Classification of Tight Sandstone and Its Micro-Nano Pores Characteristics, Songliao Basin, Northeast China

摘要

For tight sandstone, the characteristics of micro-nano pores are an important factor to determine the reservoir physical properties and oil-gas productivity. In this paper, the technology of scanning electron microscopy, casting sheet, physical property analysis, and conventional mercury injection are used to study the micro-nano pores structure of tight sandstone reservoirs of Gaotaizi oil layer in Qijia area, Songliao Basin. According to the shape, position, and distribution of mercury injection curve, the displacement pressure and the maximum mercury saturation, the tight sandstone reservoirs are divided into type A, type B, and type C. Then for each type of reservoirs, the distribution of porosity and permeability, the pore genetic types were analyzed comprehensively. The results show that there is a clear-cut distinction between different types of reservoirs in permeability and pore types. The further analysis to the oil-bearing ability shows that there is a significant positive correlation between the oil-bearing grade and the types of reservoirs. The reservoir of type B has showed the relatively better oil and gas display among the three types of reservoirs, and for its largest numbers as well, the type B reservoir would be the main body to increase the production and the focus of future exploration in the Qijia area.