Marine controlled-source electromagnetic (CSEM) surveying has been in commercial use for predrill reservoir appraisal and hydrocarbon exploration for 10 years. Although a recent decrease has occurred in the number of surveys and publications associated with this technique, the method has become firmly established as an important geophysical tool in the offshore environment. This is a consequence of two important aspects associated with the physics of the method: First, it is sensitive to high electrical resistivity, which, although not an unambiguous indicator of hydrocarbons, is an important property of economically viable reservoirs. Second, although the method lacks the resolution of seismic wave propagation, it has a much better intrinsic resolution than potential-field methods such as gravity and magnetic surveying, which until now have been the primary nonseismic data sets used in offshore exploration. Although by many measures marine CSEM is still in its infancy, the reliability and noise floors of the instrument systems have improved significantly over the last decade, and interpretation methodology has progressed from simple anomaly detection to 3D anisotropic inversion of multicomponent data using some of the world’s fastest supercomputers. Research directions presently include tackling the airwave problem in shallow water by applying time-domain methodology, continuous profiling tools, and the use of CSEM for reservoir monitoring during production.
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“In celebration of the 75th year of publication, the Geophysics editorial team invited a collection of papers written by well-recognized experts in various areas of exploration geophysics. These invited papers not only form part of the present book, but they also appear in the September-October 2010 special section of the journal. Geophysics Today: A Survey of the Field as the Journal Celebrates its 75th Anniversary complements this special section with an additional group of papers, drawn from Geophysics during the recent past, that addresses areas the invited articles did not. The result is a snapshot of the state-ofthe- art in the field as Geophysics passes its three-quarter-century mark. This book is Geophysical References Series No. 16.”