A percolation study of electrical properties of reservoir rocks

Abstract

This paper focuses on theory studies of rock electrical properties using percolation theory. The results show that classical site and bond percolation models can well describe the characteristics of the pore connectivity and the effects on the electrical resistivity. Because of the over-idealized simplification, classical site and bond percolation models cannot well show the effects of the wettability on rock resistivity. Invasion percolation (IP) model can conveniently describe the micropores around main void space and the effects of the wettability. Therefore, it can give the results agreeing with the experimental data. At high water saturation, rock electrical properties show the Archie behavior. At low water saturation, the non-Archie behavior appears. For water-wet rock with irregular grooves and crevices, the I vs. S w curve shows downwards trend. For oil-wet sample (non-shaly sandstone, without conductive grain), the curve shows upward trend.