LOTEM electric field measurements for mapping resistive horizons in petroleum exploration

Abstract

The aims of petroleum geophysics are to define potential reservoirs, both directly and indirectly, and to provide physical properties data which will help anticipate their petrographic characteristics. In borehole geophysics the methods used include radiometric, acoustic and electrical measurements in more or less equal amounts. However, surface work is about 95% seismic, in terms of expenditure. Increasing use is being made of vertical seismic profiling, a mixed surface?borehole configuration, to help improve the resolution and precision of reflection seismic results. Developments in transient electromagnetic methods now permit them to be used in an analogous way, utilizing commercial resistivity logs with reflection seismic data. While such measurements have been possible for some time, it is only in the past year that the necessary techniques have been developed which allow us to understand the results quantitatively and thus to design surveys for specific problems.