Patent ID: 7984755
Filing Date: 2011-07-26
Classification: E21B,G01V

Abstract:
1. An electrical cased-well logging method, comprising using a sonde in the form of two current electrodes located on the opposite sides of at least three measuring electrodes; alternately applying electric current; measuring, with the use of a measuring device, during each current application, the current applied, the potential across the central measuring electrode, the potential difference between the two outer electrodes and the central measuring electrode; using the specific electrical resistivity of formation beds surrounding the well as an electrical logging parameter of cased wells, wherein use is made of a sonde having measuring electrodes spaced at distances that are required to be equal; additional measuring devices are used to measure the differences in electrical field potentials between a current electrode that is not supplied with current on connection and the central measuring electrodes, and the specific electrical resistivity is found from the formula: wherein ρ bed is specific electrical resistivity, Ohm·m; K I Ua ΔUa ΔUa