EXPERIMENTAL STUDY ON PORE STRUCTURE AND OIL/WATER TWO-PHASE FLOW CHARACTERISTICS OF SANDSTONE RESERVOIR

The fine characterization of the micro pore structure of low-permeability sandstone has become the key technology for the efficient development of this kind of reservoir. In this study, the micro fine modeling of three-dimensional pore structure is established through the micro-CT scanning, and quantitative parameter characterization analysis is carried out combined with the image processing technology. Based on this, the digital rock electrical experiments of gas/water two-phase saturated low permeability sandstone is carried out, and the influence of internal factors such as wettability, saturation and micro pore throat structure parameters on the rock electrical characteristics is analyzed. The experimental results show that the porosity-based image segmentation method is used to binarize the digital image of low permeability sandstone and establish the pore network model, which can retain the real topology of pore space to the greatest extent. Rock electrical three-dimensional simulation technology of porescale has certain applicability for complex reservoirs such as low permeability sandstone. The wettability, pore throat structure and other microscopic factors have an important influence on the rock electrical characteristics. The resistivity of water-wet reservoir is lower than that of gas-wet reservoir, and the difference is more obvious in the stage of low water saturation. Among the micro pore throat structure parameters, the throat radius and pore throat ratio show a good positive correlation with the resistivity index. With the increase of coordination number, the resistivity index decreases, which is particularly prominent under low water saturation.