GEOG 4891 Lecture Notes - Lecture 8: Core Plug, Water Content, Core Sample
Document Summary
Resistivity is a basic physical property of a material. Reservoir rocks porous and permeable sedimentary rocks: sandstones, 2) limestone, 3) dolomite in their pores water, oil or gas. Core plug dry contains only air in its pore space therefore, no significant current flow. Because rock matrix and air are poor electrical conductors. Saturated with pure water no current flow. Saturated with brine (nacl solution) it is possible to flow a current through the core plug. Nacl na + cl - the electric current is carried within the rock sample by ions. The conduction within the rock is electrolytic. ro= ro (l/a) ro resistance of core plug fully saturated with water. Ro resistivity of formation fully saturated with water of resistivity rw ( m) The resistivity of undisturbed formation is defined as the true formation resistivity, rt. Factors affecting the resistivity of a clean rock are: formation water resistivity, rock structure, presence of hydrocarbons.
