It is well known that electrical conductivity of rock is closely related to the porosity, hydrologic permeability, saturation, and the type of fluid in it. These rock parameters play important roles in the development and production of hydrocarbon (petroleum and natural gas) resources. For these reasons, resistivity well logs have long been used by geologists and reservoir engineers in petroleum industries to map variations in pore fluid, to distinguish between rock types, and to determine completion intervals in wells. It is therefore a natural extension to use the electrical conductivity structure to provide additional information about the reservoir. Reservoir simulation and process monitoring rely heavily on the physical characteristics of the reservoir model At present, numerical codes use point measurements of porosity, permeability, and fluid saturation and extrapolate these data throughout a three-dimensional (3-D) grid. The knowledge of a high-resolution geophysical parameter such as electrical conductivity would aid this extrapolation and improve the reservoir simulation effort. In addition, since conductivity is sensitive to changes in the composition and state of fluids in pores and fractures it becomes an ideal method for monitoring a reservoir process. At the beginning of FY -91 a coordinated electrical and electromagnetic (EM) geophysical research program for petroleum reservoir characterization and process monitoring was initiated. Parties involved in this program include Lawrence Berkeley Laboratory (LBL), Lawrence Livermore Laboratory (LLNL), Sandia National Laboratory (SNL), and University of California at Berkeley (UCB). The overall objectives of the program were: ? To integrate research funded by DOE for hydrocarbon recovery into a focused effort to demonstrate the technology in the shortest time with the least cost. ? To assure industry acceptance of the technology developed by having industry involvement in the planning, implementation, and funding of the research. ? To focus the research on real world problems that have the potential for solution in the near term with significant energy payoff. Specific research activities conducted through this integrated effort have been in the following five general areas: ? 1) EM modeling development. ? 2) Data interpretation methods development. ? 3) Hardware and instrumentation development. ? 4) EOR and reservoir characterization. ? 5) Controlled field experiments. The primary focus of these activities was in the development of reliable inversion and imaging schemes that could yield conductivity distributions from measured electrical and EM field data. The development of accurate forward modeling algorithms and the high quality scale model experiment are necessarily the early part of the field experiment design and the inversion scheme development for ultimately monitoring the front tracking in existing reservoirs.