Iodine-bearing saline aquifer prospecting using magnetotelluric method in Golestan plain, NE Iran

Oskooi, Behrooz; Mansoori, I.

doi:10.1007/s12517-014-1634-1

Cited by 1 publication

(1 citation statement)

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“…Two-dimensional inversion of the high-resolution magnetotelluric (MT) data, including more than 500 stations, has been performed along five profiles for determinant impedance (DET) (Pedersen and Engels 2005) within the period range of 0.001 second to 700 seconds. The DET is a very practical data mode because it is rotationally invariant and 3D and galvanic distortion effects (static shift) can be suppressed to some extent (Pedersen and Engels 2005;Oskooi 2004;Oskooi et al 2005;Oskooi and Mansoori 2014;Oskooi, Pedersen, and Koyi 2014). In order to check the convergence and validation of the inversions, we tested several parameters such as different initial models with half-spaces with varying resistivity, smooth Occam, and combination of smoothness constraints and Marquardt-Levenberg damping for regularization, different vertical and horizontal smoothing weights (Constable, Parker, and Constable 1987;De Groot-Hedlin and Constable 1990), and so on.…”

Section: A N D 3 D I N V E R S I O Nmentioning

confidence: 99%

Three‐dimensional modelling of magnetotelluric data to image Sehqanat hydrocarbon reservoir in southwestern Iran

Mansoori

Oskooi

Pedersen

et al. 2015

Geophysical Prospecting

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A detailed magnetotelluric survey was conducted in 2013 in the Sehqanat oil field, southwestern Iran to map the geoelectrical structures of the sedimentary Zagros zone, particularly the boundary between the Gachsaran Formation acting as cap rock and the Asmari Formation as the reservoir. According to the electrical well logs, a large resistivity contrast exists between the two formations. The Gachsaran Formation is formed by tens to hundreds of metres of evaporites and it is highly conductive (ca. 1 Ωm–10 Ωm), and the Asmari Formation consists of dense carbonates, which are considerably more resistive (more than 100 Ωm). Broadband magnetotelluric data were collected along five southwest–northeast directed parallel lines with more than 600 stations crossing the main geological trend. Although dimensionality and strike analysis of the magnetotelluric transfer functions showed that overall they satisfied local 2D conditions, there were also strong 3D conditions found in some of the sites. Therefore, in order to obtain a more reliable image of the resistivity distribution in the Sehqanat oil field, in addition to standard 2D inversion, we investigated to what extent 3D inversion of the data was feasible and what improvements in the resistivity image could be obtained. The 2D inversion models using the determinant average of the impedance tensor depict the main resistivity structures well, whereas the estimated 3D model shows significantly more details although problems were encountered in fitting the data with the latter. Both approaches resolved the Gachsaran–Asmari transition from high conductivity to moderate conductivity. The well‐known Sehqanat anticline could also be delineated throughout the 2D and 3D resistivity models as a resistive dome‐shaped body in the middle parts of the magnetotelluric profiles.

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