Determining the depositional pattern by resistivity–seismic inversion for the aquifer system of Maira area, Pakistan
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Velocity and density measured in a well are crucial for synthetic seismic generation which is, in turn, a key to interpreting real seismic amplitude in terms of lithology, porosity and fluid content. Investigations made in the water wells usually consist of spontaneous potential, resistivity long and short normal, point resistivity and gamma ray logs. The sonic logs are not available because these are usually run in the wells drilled for hydrocarbons. To generate the synthetic seismograms, sonic and density logs are required, which are useful to precisely mark the lithology contacts and formation tops. An attempt has been made to interpret the subsurface soil of the aquifer system by means of resistivity to seismic inversion. For this purpose, resistivity logs and surface resistivity sounding were used and the resistivity logs were converted to sonic logs whereas surface resistivity sounding data transformed into seismic curves. The converted sonic logs and the surface seismic curves were then used to generate synthetic seismograms. With the utilization of these synthetic seismograms, pseudo-seismic sections have been developed. Subsurface lithologies encountered in wells exhibit different velocities and densities. The reflection patterns were marked by using amplitude standout, character and coherence. These pseudo-seismic sections were later tied to well synthetics and lithologs. In this way, a lithology section was created for the alluvial fill. The cross-section suggested that the eastern portion of the studied area mainly consisted of sandy fill and the western portion constituted clayey part. This can be attributed to the depositional environment by the Indus and the Kabul Rivers.
KeywordsResistivity Seismic inversion Aquifer Deposition Lithology Sonic logs
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- Allen, J. R. C. (1971). Physical processes of sedimentation. London: Compton.Google Scholar
- Bowling, C. J., Rodriguez, B. A., Harry, D. L., & Zheng, C. (2005). Delineating alluvial aquifer heterogeneity using resistivity and GPR data. Ground Water, 43(6), 890–903.Google Scholar
- Bowling, J. C., Harry, D. L., Rodriguez, A. B., & Zheng, C. (2007). Integrated geophysical and geological investigation of a heterogeneous fluvial aquifer in Columbus Mississippi.Google Scholar
- Duval, B. B. (2002). Sedimentary geology. Reuil- Malmaison, Editions Techip, Paris: Institut Francias du Petrole.Google Scholar
- Fetter, C. W. (1988). Applied hydrology, 2nd Edition. New York: Macmillan, 866 Third Avenue, 10022.Google Scholar
- Government of Pakistan (1998) Census report. Swabi District, N.W.F.P.Google Scholar
- Kazmi, A. H., & Jan, M. Q. (1997). Geology and tectonics of Pakistan. Graphic, 5C, 6/10, Nazimabad Karachi.Google Scholar
- Telford, W. M., Geldart, L. P., & Sheriff, R. E. (1990). Applied geophysics, 2nd edition. Cambridge University Press, The Pitt Building, Trumpington Street, Cambridge CB2 1RP.Google Scholar
- Vogelsang, D. (1995). Environmental geophysics: A practical guide. Berlin: Springer.Google Scholar
- WAPDA (1985). Ground water investigation report. Maira Area Mardan District, N.W.F.P.Google Scholar