Measuring and evaluating surface potentials for determining the boundaries of underground reservoirs

摘要

At least one string of several spaced measuring probes for the measurement of surface potentials is laid on the surface of the earth in such a manner that several probes are located outside and several probes are located inside the area of the surface over a reservoir. The potentials measured by all probes are polled in a sequence of periodic cycles. The signals from each probe are, during each cycle, filtered to separate higher-frequency changes in the signals from substantially lower- frequency changes in the signals. For the higher-frequency changes in the signals from each probe, an average and/or a sum are determined as a measure of the higher-frequency amplitudes for each probe. The higher- frequency amplitudes for the probes of a string of measuring probes are compared and the location at which the higher-frequency amplitudes for two adjacent probes change abruptly is taken to be the hydrocarbon/water interface in the underground reservoir.