PORE SCALE ANALYSIS OF ELECTRICAL RESISTIVITY IN COMPLEX CORE MATERIAL

This paper presents results of a 3D pore scale study of the resistivity properties in twelve model and reservoir core samples. Samples include sintered bead packs, homogeneous consolidated sandstones, thinly bedded sands, sucrosic dolomites, dual porosity samples and heterogeneous carbonate core material. Predictions of Archie’s cementation exponent m and saturation exponent n (under well defined wettability conditions) are in good agreement with experiment where available. We note a consistent increase in m with decreasing porosity in sandstones. The value of m in carbonates may be empirically related to the fraction of disconnected macroporosity. Under water wet conditions the simple clastic and carbonate samples exhibit Archie-type behaviour. The laminated sand exhibit strong anisotropy and the complex carbonate systems exhibit values of n that vary strongly with water saturation. Large values of n>4 are observed under idealized oil wet conditions. Pore and fluid phase connectivity is examined for the image data and used to explain trends observed in the data