Electrical Properties of Reservoir Rocks
Electrical Properties of Petroleum Reservoir Rocks Both solid grains and vacuous space make up porous rocks. With the exception of some clay minerals, the solids are nonconductors. The shape of the voids and the fluid used to fill them determine a rock's electrical characteristics. Oil, gas, and water are the fluids of importance in petroleum reserves. Nonconductors include gas and oil. Water is a conductor when it contains dissolved salts, such as NaCl, MgCl2, KCl normally found in reservoir water. Current is conducted in water by movement of ions and can therefore be termed electrolytic conduction . The resistivity of a porous material is defined by: where r is resistance, [Ω], A is cross-sectional area, [m2], L is length, [m] and resistivity is expressed in Ohm-meter (Ω.m). However, for a complex material like rock containing water and oil, the resistivity of the rock depends on: Salinity of the water Temperature Porosity Pore geometry...