A New Method for Calculating Rock Resistivity of Saturated Formation Water by Permeability

Summary The purpose of this paper is establishing the calculation relationship between formation factors (F) and permeability(K). In this paper, open experimental data of tight gas sandstone in the Western U.S. Basins are selected for analysis. 19 sandstone cores with different porosity and permeability were selected. They all measured the resistivity data in saline at concentrations of 20ppm, 40ppm, and 80ppm, respectively. Additional resistivity (Rx) are confirmed by fitting the relationship between the rock resistivity of saturated formation water (Ro) and the formation water resistivity (Rw). Both the changeable formation resistivity change factor (Fd) and additional resistivity (Rx) show a strong linear relationship with permeability in logarithmic coordinates. Additionally, we selected the experimental data from several sandstone cores and verified the existence of a suitable equation by varying the formation parameters and permeability. The results demonstrate that the fitting equation may be utilized to determine the changeable formation resistivity change factor (Fd), additional resistivity (Rx), and the rock resistivity of saturated formation water (Ro) with the varying permeability. The predicted rock resistivity of saturated formation water (Ro) is strongly correlated with the laboratory value.