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DAE

Seminar

SMART: Progress towards an optimising time-lapse geoelectrical imaging system

Wilkinson, PB (British Geological Survey (BGS))
Friday 22 July 2011, 10:00-11:00

Seminar Room 1, Newton Institute

Abstract

Electrical resistivity tomography (ERT) is a widely-used geophysical technique for shallow subsurface investigations and monitoring. A range of automatic multi-electrode ERT systems, both commercial and academic, are routinely used to collect resistivity data sets that cover large survey areas at high spatial and temporal density. But despite the flexibility of these systems, the data still tend to be measured using traditional arrangements of electrodes. Recent research by several international groups has highlighted the possibility of using automatically generated survey designs which are optimised to produce the best possible tomographic image resolution given the limitations of time and practicality required to collect and process the data. Here we examine the challenges of applying automated ERT survey design to real experiments where resistivity imaging is being used to monitor subsurface processes. Using synthetic and real examples we address the problems of avoiding electrode polarisation effects, making efficient use of multiple simultaneous measurement channels, and making optimal measurements in noisy environments. These are essential steps towards implementing SMART (Sensitivity-Modulated Adaptive Resistivity Tomography), a robust self-optimising ERT monitoring system. We illustrate the planned design and operation of the SMART system using a simulated time-lapse experiment to monitor a saline tracer. The results demonstrate the improvements in image resolution that can be expected over traditional ERT monitoring.

Presentation

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