Resolution Analysis of Different Electrode Array on Synthetic Earth Models of Geological Relevance
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Date
2016
Authors
Adeoti, Lukumon
Ishola, K.S
Imenvbore, I
Ojo, A.O
Adegbola, R.B
Afolabi, S.O
Journal Title
Journal ISSN
Volume Title
Publisher
Journal of the Nigerian Association of Mathematical Physics
Abstract
This study compares the resolution capabilities of different electrode arrays in
imaging 2-D earth models by employing the Finite difference modeling scheme. The
software called RES2DMOD was used to generate 2-D synthetic models having a
resistive block in a conductive environment with different resistivity values, three
conductive blocks in a highly resistive environment and a high resistive dyke in
conductive environment. The synthetic data were contaminated with 6% Gaussian
noise and inverted using the RES2DINV inversion software. The reconstructed
resistivity values reproduced from a block of 100 Ωm at a depth of 2.8 m by Dipoledipole,
Pole-dipole, Wenner-schlumberger and Wenner arrays are 94.1 Ωm, 90.9 Ωm,
77.8 Ωm and 46.7 Ωm respectively. For a dyke model with a resistivity of 500 Ωm, the
inverted resistivity values are 355 Ωm, 312 Ωm, 281 Ωm, and 291 Ωm respectively.
This shows that the dipole-dipole array recover a more accurate resistivity value of the
block. However, the pole dipole array gives a higher resolution image at deeper depth
when two blocks of different resistivity values in a conductive environment along a
spread of 35 m. For the same structure, the dipole-dipole, pole-dipole, schlumberger
and wenner arrays gave a depth estimates with variation of 9.12m, 13.6m, 7.88m and
6.75m from the true value. The study shows that dipole dipole gives best resolution for
vertical structures such as dykes while the Pole-dipole seems more efficient for this
same purpose at deeper depth. Also, Wenner array gives low resolution while
investigating dipping structures. Schlumberger array was able to image sharp
boundaries between two lithological units but gives poor results for dipping
structures.
Description
Keywords
Finite difference method , synthetic model , RES2DMOD , RES2DINV , resolution