Borehole radar modeling for reservoir monitoring applications

The use of down-hole sensors and remotely controlled valves in wells provide enormous benefits to reservoir management and oil production. We suggest borehole radar measurements as a promising technique capable of monitoring the arrival of undesired fluids in the proximity of production wells. The high radar sensitivity to contrasts in fluid saturation changes would make this technique suitable for steam chamber monitoring in Steam Assisted Gravity Drainage (SAGD) processes and water front monitoring in thin oil rim environments. We use 2D FDTD modeling to evaluate the most significant technical and reservoir constraints. Technical constraints are given by the wellbore. A high dielectric medium surrounding the EM source is necessary to avoid destructive interference with the reflections of the metal casing. The main reservoir constraint is given by the conductivity of the formation where the radar is located; high conductivity makes attenuation and phase distortion too high for wave propagation. Additional constraints are given by the complexity of the reservoir and the dynamic of the fluids. Time-lapse changes in the heterogeneity of the background formation strongly affect the retrieval of the target reflections and gradual fluid saturation changes reduce the amplitude of the reflections.© 2010, Society of Petroleum Engineers