Designed with equally spaced electrodes positioned on an insulated pad, the Microlog provides qualitative estimate of permeability.  The tool senses the presence or absence of mudcake, which is a result of mud filtrate invading a permeable formation and causes negative separation in high porosity sands.  Zones that do not allow mud filtrate to invade the formation indicate a non permeable formation.  This information can help in making informed completion decisions.