Abstract:

The features of micropore throat in high pressure and lowpermeability sandstone reservoir of deep section were analyzed by using the constantrate mercury injection technology. The research shows there are little difference in the pores sizes and distribution, the pore radius is unimodal distribution, and the main peak is from 100 μm to 300 μm. Throat radius is the main factor that controls the reservoir property. The relation between the permeability and the throat radius is better than that between it and the pore radius. There is better correlation between the reservoir property and the pore throat parameters such as the effective throat radius, pore radius, throat volume, pore volume, and poretothroat radius ratio. When it comes to the high permeability sandstone sample, the effective poretothroat radius ratio is low, and its distribution frequency is high. The better the permeability is, the lower the poretothroat radius ratio is, and the more concentrated the distribution of the poretothroat radius ratio is. Its analyzed that in the pore throat parameters of the constantrate mercury injection, the numerical values such as the displacement pressure(pT), the median pressure(pc50), and the largest injection mercury saturation(SHgmax) are lower than that of the conventional mercury injection, and the largest continuous throat radius(Rmax), the median radius(r50) are larger than that of the conventional mercury injection. Compared with the conventional mercury injection, the pore throat feature parameters from the constantrate mercury injection are more accurate.

Key words: high pressure and lowpermeability sandstone reservoir of deep section, micro pore throat feature, poretothroat radius ratio, constantrate mercury injection, pore throat parameter, reservoir quality