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3D resistivity inversion using 2D measurements of the electric field
Author(s) -
Jackson P.D.,
Earl S.J.,
Reece G.J.
Publication year - 2001
Publication title -
geophysical prospecting
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.735
H-Index - 79
eISSN - 1365-2478
pISSN - 0016-8025
DOI - 10.1046/j.1365-2478.2001.00241.x
Subject(s) - electric field , inversion (geology) , electrical resistivity and conductivity , electrode , dipole , smoothness , regional geology , electrode array , computational physics , geology , physics , mathematical analysis , mathematics , hydrogeology , geotechnical engineering , quantum mechanics , paleontology , metamorphic petrology , structural basin
Field and ‘noisy’ synthetic measurements of electric‐field components have been inverted into 3D resistivities by smoothness‐constrained inversion. Values of electrical field can incorporate changes in polarity of the measured potential differences seen when 2D electrode arrays are used with heterogeneous ‘geology’, without utilizing negative apparent resistivities or singular geometrical factors. Using both the X ‐ and Y ‐components of the electric field as measurements resulted in faster convergence of the smoothness‐constrained inversion compared with using one component alone. Geological structure and resistivity were reconstructed as well as, or better than, comparable published examples based on traditional measurement types. A 2D electrode grid (20 × 10), incorporating 12 current‐source electrodes, was used for both the practical and numerical experiments; this resulted in 366 measurements being made for each current‐electrode configuration. Consequently, when using this array for practical field surveys, 366 measurements could be acquired simultaneously, making the upper limit on the speed of acquisition an order of magnitude faster than a comparable conventional pole–dipole survey. Other practical advantages accrue from the closely spaced potential dipoles being insensitive to common‐mode noise (e.g. telluric) and only 7% of the electrodes (i.e. those used as current sources) being susceptible to recently reported electrode charge‐up effects.