Study on Fractal Characteristics of Pore Structure in Salt Rock Based on Mercury Injection Data

Constant-speed mercury injection and conventional mercury injection techniques are utilized in this paper to analysis the pore meso-structure in salt rock, including the size and distribution of the pores and pore throats respectively It is observed that the small sub-pores are dominant in salt rock. Based on the pore-throat parameters obtained from mercury injection test, combined with the geometric fractal theory, the distribution characteristics of the pore and throat in salt rock are investigated. We derived the contribution rate of a single throat penetration, the average radius of the throat and the mesoscopic homogeneity coefficient, all of which were characterized by the fractal dimension. The results show that distributions of pore throat and pore in salt rock belong to two different systems; the former conforms to fractal structure while the latter does not. The correlation between fractal dimension of pore throat distribution and permeability is poor. Small throat contributes a lot to the permeability of salt rock. The vast majority of the salt rock samples that have a greater fractal dimension of pore throat distribution show stronger heterogeneity.