This paper reviews the geological conditions, data density, and acquisition geometry that have direct influence on the sensitivity and resolution capacity of several electrode configurations. The parameters appreciate the effectiveness of automated multichannel system which has evolved several electrode arrays that are cost effective, reduction in survey time, high sensitivity, and resolution capacity in 2D and 3D resistivity tomographies. The arrays are pole-pole, pole-dipole, pole-bipole, dipole-dipole, Wenner, Wenner- , , gradient, midpoint-potential-referred, Schlumberger, square, and Lee-partition arrays. The gradient array and midpoint-potential-referred are well suited for multichannel surveying and gradient array images are comparable to dipole-dipole and pole-dipole. 2D electrical resistivity surveys can produce out-of-plane anomaly of the subsurface which could be misleading in the interpretation of subsurface features. Hence, a 3D interpretation model should give more accurate results, because of the increase in the reliability of inversion images and complete elimination of spurious features. Therefore, the reduction of anomaly effects and damping factor due to signal to noise ratio result in better spatial resolution image, thus enhancing its usage in environmental and engineering research. 1. Introduction Most targets of environmental and engineering interest are at shallow depths. Geophysical responses from near-surface sources usually treated as noise in traditional geophysical exploration surveys are often the targets of interest in environmental and engineering investigations. The subsurface geology can be complex, subtle, and multiscale such that spatial variations can change rapidly both laterally and vertically. Thus, a closely spaced grid of observation points is required for their accurate characterization, high spatial resolution of the anomaly, and good target definition. Survey design in geoelectrical resistivity surveys must take into account the capabilities of the data acquisition system, heterogeneities of the subsurface electrical resistivities, and the resolution required. Other factors to be considered are the area extent of the site to be investigated, the cost of the survey, and the time required to complete the survey [1]. Geoelectrical surveys were introduced by Conrad Schlumberger and Marcel Schlumberger in 1932 and have subsequently been investigated by many researchers for numerous electrode configurations and subsurface structures. This concept has been used in the qualitative comparison of the effective
References
[1]
P. A. Ahzegbobor, Acquisition geometry and inversion of 3D geoelectrical resistivity imaging data for environmental and engineering investigations [Ph.D. thesis], Physics Department, Covenant University, Ota, Nigeria, 2010.
[2]
R. D. Barker, “Signal contribution sections and their use in resistivity studies,” Geophysical Journal, vol. 59, no. 1, pp. 123–129, 1979.
[3]
M. Muskat and H. H. Evinger, “Current penetration in direct current prospecting,” Geophysics, vol. 6, pp. 397–427, 1941.
[4]
H. M. Evjen, “Depth factor and resolving power of electrical measurements,” Geophysics, vol. 3, pp. 78–85, 1938.
[5]
A. Roy and A. Apparao, “Depth of investigation in direct current methods,” Geophysics, vol. 36, pp. 943–959, 1971.
[6]
A. Roy, “Depth of investigation in Wenner, three-electrode and dipole-dipole DC resistivity methods,” Geophysical Prospecting, vol. 20, no. 2, pp. 329–340, 1972.
[7]
O. Koefoed, “Discussion on “Depth of investigation in direct current methods” by A. Roy and A. Apparao,” Geophysics, vol. 37, pp. 703–704, 1972.
[8]
D. S. Parasnis, “More comments on “A theorem for Dc regimes and some of its consequences” by A. Roy,” Geophysical Prospecting, vol. 32, pp. 139–141, 1984.
[9]
S. C. Guerreiro, “Comment on “A theorem for direct current regimes and some of its consequences” by A. Roy and some related papers and comments,” Geophysical Prospecting, vol. 31, no. 1, pp. 192–195, 1983.
[10]
B. Banerjee and B. P. Pal, “A simple method for determination of depth of investigation characteristics in resistivity prospecting,” Exploration Geophysics, vol. 17, pp. 93–95, 1986.
[11]
M. N. Nabighian and C. L. Elliot, “Negative induced polarization effects from layered media,” Geophysics, vol. 41, no. 6, pp. 1236–1255, 1976.
[12]
K. K. Roy and H. M. Elliot, “Some observations regarding depth of exploration in D.C. electrical methods,” Geoexploration, vol. 19, no. 1, pp. 1–13, 1981.
[13]
L. S. Edwards, “A modified pseudosection for resistivity and induced polarization,” Geophysics, vol. 42, no. 5, pp. 1020–1036, 1977.
[14]
R. D. Barker, “Depth of investigation of collinear symmetrical four-electrode arrays,” Geophysics, vol. 54, no. 8, pp. 1031–1037, 1989.
[15]
T. Dahlin and B. Zhou, “A numerical comparison of 2D resistivity imaging with 10 electrode arrays,” Geophysical Prospecting, vol. 52, no. 5, pp. 379–398, 2004.
[16]
M. H. Loke, “Tutorial: 2D and 3D electrical imaging surveys,” 2004, http://www.geotomosoft.com/.
[17]
O. Pazdirek and V. Blaha, “Examples of resistivity imaging using ME-100 resistivity field acquisition system,” in Proceedings of the EAGE 58th Conference and Technical Exhibition Extended Abstracts, Amsterdam, The Netherlands, 1996.
[18]
M. H. Loke, “Electrical Imaging surveys for environmental and engineering studies: a practical guide to 2D and 3D surveys,” 2001, http://www.geotomosoft.com/.
[19]
P. Stummer, H. Maurer, and A. G. Green, “Experimental design: electrical resistivity data sets that provide optimum subsurface information,” Geophysics, vol. 69, no. 1, pp. 120–139, 2004.
[20]
P. B. Wilkinson, P. I. Meldrum, J. E. Chambers, O. Kuras, and R. D. Ogilvy, “Improved strategies for the automatic selection of optimized sets of electrical resistivity tomography measurement configurations,” Geophysical Journal International, vol. 167, no. 3, pp. 1119–1126, 2006.
[21]
A. Furman, T. P. A. Ferré, and G. L. Heath, “Spatial focusing of electrical resistivity surveys considering geologic and hydrologic layering,” Geophysics, vol. 72, no. 2, pp. F65–F73, 2007.
[22]
T. Hennig, A. Weller, and M. M？ller, “Object orientated focussing of geoelectrical multielectrode measurements,” Journal of Applied Geophysics, vol. 65, no. 2, pp. 57–64, 2008.
[23]
J. Chambers, R. Ogilvy, P. Meldrum, and J. Nissen, “3D resistivity imaging of buried oil- and tar-contaminated waste deposits,” European Journal of Environmental and Engineering Geophysics, vol. 4, no. 1, pp. 3–14, 1999.
[24]
T. Dahlin, On the Automation of 2D Resistivity Surveying for Engineering and Environmental Applications, Lind University, 1993.
[25]
Y. Sasaki, “Resolution of resistivity tomography inferred from numerical simulation,” Geophysical Prospecting, vol. 40, no. 4, pp. 453–463, 1992.
[26]
T. Dahlin and M. H. Loke, “Resolution of 2D Wenner resistivity imaging as assessed by numerical modelling,” Journal of Applied Geophysics, vol. 38, no. 4, pp. 237–249, 1998.
[27]
A. I. Olayinka and U. Yaramanci, “Assessment of the reliability of 2D inversion of apparent resistivity data,” Geophysical Prospecting, vol. 48, no. 2, pp. 293–316, 2000.
[28]
H. Militzer, R. Rosler, and W. Losch, “Theoretical and experimental investigations for cavity research with geoelectrical resistivity methods,” Geophysical Prospecting, vol. 27, no. 3, pp. 640–652, 1979.
[29]
G. M. Habberjam, “Apparent resistivity anisotropy and strike measurements,” Geophysical Prospecting, vol. 23, no. 2, pp. 211–247, 1975.
[30]
G. M. Habberjam, “The effects of anisotropy on square array resistivity measurements,” Geophysical Prospecting, vol. 20, no. 2, pp. 249–266, 1972.
[31]
R. G. Van Nostrand and K. L. Cook, “Interpretation of resistivity data,” U. S. Geological Survey Professional, 499 pages, 1966, http://books.google.com/.
[32]
K. Spitzer and H.-J. Kümpel, “3D FD resistivity modelling and sensitivity analyses applied to a highly resistive phonolitic body,” Geophysical Prospecting, vol. 45, no. 6, pp. 963–982, 1997.
[33]
P. R. McGillivray and D. W. Oldenburg, “Methods for calculating Frechet derivatives and sensitivities for the non-linear inverse problem: a comparative study,” Geophysical Prospecting, vol. 38, no. 5, pp. 499–524, 1990.
[34]
D. E. Boerner and G. F. West, “Frechet derivatives and single scattering theory,” Geophysical Journal International, vol. 98, no. 2, pp. 385–390, 1989.
[35]
D. W. Oldenburg, “The interpretation of direct current measurements,” Geophysics, vol. 43, no. 3, pp. 610–625, 1978.
[36]
Y. Sasaki, “3-D resistivity inversion using the finite-element method,” Geophysics, vol. 59, no. 12, pp. 1839–1848, 1994.
[37]
M. Noel and B. X. Biwen Xu, “Archaeological investigation by electrical resistivity tomography: a preliminary study,” Geophysical Journal International, vol. 107, no. 1, pp. 95–102, 1991.
[38]
S. K. Park and G. P. Van, “Inversion of pole-pole data for 3-D resistivity structure beneath arrays of electrodes,” Geophysics, vol. 56, no. 7, pp. 951–960, 1991.
[39]
K. Spitzer, “The three-dimensional DC sensitivity for surface and subsurface sources,” Geophysical Journal International, vol. 134, no. 3, pp. 736–746, 1998.
[40]
J. A. Stratton, Electromagnetic Theory, McGraw-Hill, New York, NY, USA, 1941.
[41]
R. F. Harrinton, Harmonic Electromagnetic Fields, Electrical and Electronic Engineering Series, McGraw-Hill, New York, NY, USA, 1961.
[42]
F. S. Grant and G. F. West, Interpretation Theory in Applied Geophysics, McGraw-Hill, New York, NY, USA, 1965.
[43]
S. H. Ward and G. W. Hohmann, “Electromagnetic theory for geophysical applications,” in Electromagnetic Methods in Applied Geophysics, Investigations in Geophysical Series, M. N. Nabighian, Ed., vol. 1, pp. 131–312, Society of Exploration Geophysicists, Tulsa, Okla, USA, 1987.
[44]
G. V. Keller and F. C. Frischknecht, Methods in Geophysical Prospecting, Pergamo Press, 1966.
[45]
W. M. Telford, L. P. Geldart, R. E. Sheriff, and D. A. Keys, Applied Geophysics, Cambridge University Press, Lodon, UK, 1976.
[46]
T. Dahlin and M. H. Loke, “Quasi-3D resistivity imaging-mapping of three-dimensional structures using two-dimensional DC resistivity techniques,” in Proceedings of the 3rd Meeting of the Environmental and Engineering Geophysical Society, pp. 143–146, 1997.
[47]
D. H. Griffiths, J. Turnbull, and A. I. Olayinka, “Two-dimensional resistivity mapping with a complex controlled array,” First Break, vol. 8, no. 4, pp. 121–129, 1990.
[48]
E. S. Robinson and C. Coruh, Exploration Geophysics, John Wiley & Sons, New York, NY, USA, 1988.
[49]
R. A. V. Overmeeren and I. L. Ritsema, “Continuous vertical electrical sounding,” First Break, vol. 6, no. 10, pp. 313–324, 1988.
[50]
O. Koefoed, Geosounding Principles 1: Resistivity Sounding Measurements, Elsevier Science, Amsterdam, The Netherlands, 1979.
[51]
H. M. Mooney, E. Orellana, H. Pickett, and L. Tornheim, “A resistivity computation method for layered earth models,” Geophysics, vol. 31, pp. 192–203, 1966.
[52]
D. P. Ghosh, “The application of linear filter theory to the direct interpretation of geoelectrical resistivity sounding measurements,” Geophysical Prospecting, vol. 19, pp. 192–217, 1971.
[53]
J. R. Inman, J. Ryu, and S. H. Ward, “Resistivity inversion,” Geophysics, vol. 38, no. 6, pp. 1088–1108, 1973.
[54]
A. A. R. Zohdy, “A new method for the automatic interpretation of Schlumberger and Wenner sounding curves,” Geophysics, vol. 54, no. 2, pp. 245–253, 1989.
[55]
P. Furness, “Gradient array profiles over thin resistive veins,” Geophysical Prospecting, vol. 41, no. 1, pp. 113–130, 1993.
[56]
A. Dey and H. F. Morrison, “Resistivity modelling for arbitrarily shaped three- dimensional structure,” Geophysics, vol. 44, no. 4, pp. 753–780, 1979.
[57]
R. S. Varga, Matrix Iteration Analysis, Prentice-Hall, Englewood Cliffs, NJ, USA, 1962.
[58]
K. S. Cheng, S. J. Simske, D. Isaacson, J. C. Newell, and D. G. Gisser, “Errors due to measuring voltage on current-carrying electrodes in electric current computed tomography,” IEEE Transactions on Biomedical Engineering, vol. 37, no. 1, pp. 60–65, 1990.
