Abstract: Electrically conductive oil base drilling fuids with carbon nanotubes have either an organic base (oil) or a base that is an emulsion of water in oil (invert emulsion) and contains carbon nanotubes dispersed in oil. These drilling fluids may be prepared by either (1) the addition of electrically conductive dispersions of carbon nanotubes in oil to conventional oil base drilling fluids (unweighted or weighted) or (2) the sonication of the mixture of oil pre-wetted carbon nanotubes with unweighted conventional oil base drilling fluids. The electrically conductive dispersions of carbon nanotubes in oil may be prepared by sonication or by microfluidization. The oil may be a mineral oil, paraffin oil, synthetic oil, or diesel oil. The electrically conductive oil-based drilling fluids may further contain ionic, non-ionic or polymeric surfactants.