• journal_title：Geophysics
• Contributor：Mathieu Darnet ; Matthew C. K. Choo ; René-Edouard Plessix ; Mark L. Rosenquist ; Kok Yip-Cheong ; Eldon Sims ; John W. K. Voon
• Publisher：Society of Exploration Geophysicists
• Date：2007-
• Format：text/html
• Language：en
• Identifier：10.1190/1.2435201
• journal_abbrev：Geophysics
• issn：0016-8033
• volume：72
• issue：2
• firstpage：WA97
• section：Special Section - Marine Controlled-Source Electromagnetic Methods

d="p-1">Controlled-source electromagnetic (CSEM) field surveys offer a geophysical method to discriminate between high and low hydrocarbon saturations in a potential reservoir. However, the same geological processes that create the possible hydrocarbon reservoir may also create topography and near-surface variations of resistivity (e.g., shallow gas or hydrates) that can complicate the interpretation of CSEM data. In this paper, we discuss the interpretation of such data over a thrust belt prospect in deepwater Sabah, Malaysia. We show that detailed modeling of the key scenarios can help us understand the contributions of topography, near-surface hydrates, and possible hydrocarbons at reservoir depth. Complexity at the surface and at depth requires a 3D electromagnetic modeling code that can handle realistic ten-million-cell models. This has been achieved by using an iterative solver based on a multigrid preconditioner, finite-difference approach with frequency-dependent grid adaptation.