Design and application of multi-channel simultaneous detection system for well-earth potential

Abstract

Well-earth ERT (electrical resistance tomography) technology is an important geophysical exploration method which studies the location distribution of remaining oil. Based on virtual instrument technology, the author designs a set of multi-channel simultaneous detection system. It adopts multi-channel simultaneous sampling, bipolar and differential inputs, analog LPF (low pass filter), FIR digital filter, and linear accumulated digital averaging method or techniques to suppress electromagnetic noise and improve SNR (signal-to-noise ratio); uses digital signal process method to remove the overshoot, avoided huge errors and improved accuracy of measurement; adopts feedback compensative method to exclude the influence of SP(spontaneous potential) and cover a wide dynamic measurable scope; spectrum analysis method is used for judging all electrodes earthing situation correctly; the USB2.0 technique is used to solve the problem of bulky multi-channel data transmission to achieve high-speed data transmission between hardware and PC. The Liao He oilfield survey results show that the system is characterized with high efficiency, portable and strong antijiamming capability.