An introduction to marine controlled-source electromagnetic methods for hydrocarbon exploration

Abstract

Early development of marine electromagnetic methods, dating back about 80 years, was driven largely by defense/military applications, and use for these purposes continues to this day. Deepwater, frequency-domain, electric dipole-dipole, controlled-source electromagnetic (CSEM) methods arose from academic studies of the oceanic lithosphere in the 1980s, and although the hydrocarbon exploration industry was aware of this work, the shallow-water environments being explored at that time were not ideally suited for its use. Low oil prices and increasingly successful results from 3D seismic methods further discouraged investment in costly alternative geophysical data streams. These circumstances changed in the late 1990s, when both Statoil and ExxonMobil began modeling studies and fieldtrials of CSEM surveying in deep water (around [Formula: see text] or deeper), specifically for characterizing the resistivity of previously identified drilling targets. Trials offshore Angola in 2000–2002 by both these companies showed that CSEM data can successfully be used to evaluate reservoir resistivity for targets as deep as several thousand meters. Both companies leveraged instrumentation and expertise from the academic community to make swift progress. The resulting rapid growth in the use of marine EM methods for exploration has created a demand for trained personnel that is difficult to meet; nevertheless, at this time, CSEM data represent a commercial commodity within the exploration business, and acquisition services are offered by three companies. The ability to determine the resistivity of deep drilling targets from the seafloor may well make marine CSEM the most important geophysical technique to emerge since 3D reflection seismology.

Marlim R3D: a realistic model for CSEM simulations - phase I: model building

“…The application of CSEM in the oil industry began in the 2000s, with the pioneering survey in deep waters of Angola, and reached a market scale in the year of 2004 (Constable & Srnka 2007). In 2007, the first reduction in the business activities happened.…”

“…The receivers are sensors that, deposited on the ocean floor, can measure up to three components (X, Y, Z). More details on the method's theory can be obtained in Edwards (2005) and Constable and Srnka (2007). The CSEM method had its initial development around the 1970 decade, aimed at solving academic studies in the mapping of the resistivity structure of the marine floor at great depths (Constable & Cox 1996).…”

A multi-domain decomposition-based Fourier finite element method for the simulation of 3D marine CSEM measurements

“…As an example of surface-based measurements, we consider a marine controlled source EM (CSEM) acquisition system [12]. It consists of a towed electric-dipole source and a number of seafloor electric and magnetic field receivers, as illustrated in Fig.…”

Computational Modeling of Geoelectrical Soundings using PML-FDTD

“…Some of them are the Marine Controlled Source Electromagnetic (mCSEM) [1]- [7], which has been used successfully to complement deep and ultradeep reservoir exploration seismic activities, and Loggingwhile-drilling (LWD) tools modeling, that is very useful for direction and/or horizontal wells geodirectional drilling. [8]- [19].…”