Pore Structure Characterization and Permeability Evaluation of Deep Tight Dolomite Reservoirs Based on High‐Pressure Mercury Intrusion

ABSTRACT Deep dolomite reservoirs are predominantly tight reservoirs characterized by strong heterogeneity, which is primarily induced by various diagenetic processes such as dissolution, compaction, and cementation. The scientific characterization and evaluation of deep dolomite reservoir heterogeneity is the key problem to be solved in effective reservoir prediction. In this study, 12 deep dolomite samples were tested by rock physical properties measurement and high‐pressure mercury intrusion test. The pore throat distribution characteristics and fractal characteristics of each sample were systematically analyzed, and then a power‐law permeability model based on representative pore radius and a fractal permeability model were respectively established. The results demonstrate that the deep dolomite samples exhibit significant heterogeneity, accompanied by a wide range of permeability values spanning multiple orders of magnitude. Furthermore, the storage space is primarily composed of micro‐nano pores with multipeak characteristics. The correlation between the permeability of samples and the parameter of fractal dimension, denoted by ϕ (4‐ D )/ D , has been established. The pore throat radius corresponding to 25% mercury saturation can be regarded as a representative radius, and a power‐law model describing permeability variation is constructed by combining it with porosity. The established fractal model and the power‐law model can better explain the permeability heterogeneity of the deep dolomite. The findings of the research will provide a theoretical framework for the analysis of high‐pressure mercury intrusion data and the evaluation of permeability.