New aspects of through-casing resistivity theory

What is it about?

We find a closed-form solution for the basic model of the through-casing resistivity measurement. The solution reveals fundamental characteristics of the measurement. Explicit expressions are found for the characteristic length and k-factor. The latter displays a significant dependence on the resistivity of the formation. It is shown that a transition from a cylindrical to spherical pattern of the current flow in the formation happens at a radial distance controlled by the characteristic length. This phenomenon bounds the "current tube" resistance. We also discuss the corresponding implications for the interpretation of the through-casing resistivity logs.

Featured Image

Why is it important?

The extended abstract defines all the essential parameters of the basic model of the measurement of the formation resistivity carried out from inside of the metal cased borehole.