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Fast computation of optimized electrode arrays for 2D resistivity surveys

By M.H. Loke, P. Wilkinson and J. Chambers

Abstract

Four different methods to automatically select an optimal set of array configurations that gives the maximum subsurface resolution with a limited number of measurements for 2D electrical imaging surveys were tested. The first (CR) method directly calculates the change in the model resolution for each new array added to the base data set, and uses this to select array configurations that gave the maximum model resolution. However this method is the slowest. The algorithm used by the CR method for calculating rank-one updates was optimized to reduce computational time by a factor of eighty. The sequence of calculations was modified to reduce the traffic between the computer main memory and the CPU registers. Further code optimizations were made to take advantage of the parallel processing capabilities of modern CPUs. The second (ETH) and third (BGS) methods use approximations based on the sensitivity values to estimate the change in the model resolution matrix. The ETH and BGS methods, respectively, use the first and second power of the sensitivity values to calculate approximations of the model resolution. Both methods are about an order of magnitude faster than the CR method. The results obtained by the BGS method are significantly better than the ETH method, and it approaches that of the CR method. The fourth method (BGS–CR) uses a combination of the BGS and CR methods. It produces results that are almost identical to the CR method but is several times faster. The different methods were tested using data from synthetic models and field surveys. The models obtained from the inversion of the data sets generated by the four different methods confirm that the models generated by the CR method have the best resolution, followed by the BGS–CR, BGS and ETH methods.\ud \u

Topics: Computer Science, Physics, Earth Sciences, Mathematics
Publisher: Elsevier
Year: 2010
DOI identifier: 10.1016/j.cageo.2010.03.016
OAI identifier: oai:nora.nerc.ac.uk:12867

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Citations

  1. (1979). Signal contribution sections and their use in resistivity studies.
  2. (1989). Depth of investigation of collinear symmetrical four-electrode arrays.
  3. (2005). 2-D resistivity surveying for hydrocarbons – A primer.
  4. (1983). York solid and drift (Sheet 63). 1:50 000. British Geological Survey,
  5. (2001). Parallel Programming in OpenMP.
  6. (1996). 2D resistivity surveying for environmental and engineering applications.
  7. (2000). Short note on electrode charge-up effects in DC resistivity data acquisition using multi-electrode arrays.
  8. (2004). A numerical comparison of 2-D resistivity imaging with 10 electrode arrays.
  9. (2005). Applying petrophysical models to radar travel time and electrical resistivity tomograms: Resolution-dependent limitations.
  10. (1990). Occam's inversion to generate smooth, two-dimensional models from magnetotelluric data.
  11. (1977). A modified pseudosection for resistivity and induced-polarization.
  12. (1994). Applied geophysical inversion.
  13. (1998). Nonlinear inversion using general measures of data misfit and model structure.
  14. (1996). Matrix computations (Third Edition).
  15. (2005). 32/64-bit 80x86 assembly language architecture.
  16. (2002). A comparison of the Gauss-Newton and quasi-Newton methods in resistivity imaging inversion.
  17. (2003). A comparison of smooth and blocky inversion methods in 2D electrical imaging surveys.
  18. (1989). Geophysical data analysis: Discrete inverse theory (Revised Edition).
  19. (2005). Injection electrode overprinting.
  20. (2007). Resolution analysis of geophysical images: Comparison between point spread function and region of influence measures.
  21. (2009). Automated Monitoring of Coastal Aquifers with Electrical Resistivity Tomography.
  22. (1996). Examples of resistivity imaging using ME-100 resistivity field acquisition system. In:
  23. (1984). Lithostratigraphical nomenclature of the Lias Group in the Yorkshire basin.
  24. (1992). Numerical Recipes in C (Second Edition).
  25. (1995). Jurassic of the Cleveland Basin,
  26. (2000). Aquifer characterization in the Blue Ridge Physiographic Province using resistivity profiling and borehole geophysics.
  27. (2004). Experimental design: Electrical resistivity data sets that provide optimum subsurface information.
  28. (2006). Improved strategies for the automatic selection of optimized sets of electrical resistivity tomography measurement configurations.
  29. (2006). Comparison of the spatial resolution of standard and optimised electrical resistivity tomography arrays. In:
  30. (1991). Archaeological investigations by electrical resistivity tomography: a preliminary study.

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