Borehole radar monitoring in shallow oilfield applications

We use a 2D Finite-Difference-Time-Domain electromagnetic (EM) wave simulator to model a borehole radar system located in a shallow oilfield production environment. Main aim of this study is to investigate if radar technology is suitable for detecting and monitoring fluid saturation changes in the proximity of production wells. An analysis of the main constraints for an implementation of a radar system as permanent down-hole sensor has been performed. The main constraints are given by the conductivity of the formation and by the effect of the borehole casing on the emitted EM signal. An antenna shield is necessary to reduce the destructive interference between the emitted signal and the reflections by the metal parts of the wellbore. Moreover, different reservoir scenarios are considered. The heterogeneity of the background formation strongly affects the retrieval of the target reflections and gradual fluid saturation changes reduce the amount of the reflections.