--> --> Abstract: Testing the Feasibility of CSEM Technology Offshore West Africa, by Aristofanis Stefatos, Torolf Wedberg, Peter Gelting, Mikhail Boulaenko, Alexander Verechtchaguine, and Jonny Hesthammer; #90082 (2008)

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Testing the Feasibility of CSEM Technology Offshore West Africa

Aristofanis Stefatos1, Torolf Wedberg1, Peter Gelting1, Mikhail Boulaenko2, Alexander Verechtchaguine1, and Jonny Hesthammer2
1Research & Development, Rocksource ASA, Bergen, Norway
2Department of Earth Sciences, University of Bergen, Bergen, Norway

Over the last years Rocksource has studied the application of Controlled Source Electromagnetic (CSEM) Surveys for hydrocarbon detection in numerous shallow and deep water sites offshore West Africa. Extending from the coasts of Morocco down to the coasts of Namibia, a variety of prospects over very different geological settings have been tested by synthetic CSEM data modeling to examine how feasible the application of this new and very promising exploration technology is.

The synthetic modeling assumes a simple CSEM survey line running over the long axis of the prospect. For each case the survey line consists of as many receivers as required to achieve full prospect coverage and maintain 1km distance between receivers. In total 25 such models were built, each one representing a single prospect. Full three dimensional models were constructed using the prospects most probable size (P50 case).

The shallowest water depth tested is less than 100m while the deepest exceeds 2500m. Accordingly the depth to the prospect bellow the mud line varies from a minimum of 600m to more than 3000m depth.
Although many input parameters to the CSEM synthetic modeling are poorly constrained in order to deduce safe case specific conclusions, these studies reveal the present limitations of the technology when applied offshore West Africa. Apart from the current technological limitations, the results highlight the importance of the background resistivity distribution, the prospect size and resistivity contrast as controlling parameters on the expected detectability of the prospects.

Overall the feasibility studies are considered very promising, suggesting that the geology offshore West Africa provides a rather friendly setting for applying the CSEM exploration technology.

AAPG International Conference and Exhibition, Cape Town, South Africa 2008 © AAPG Search and Discovery