Abstract

Controlled-source electromagnetics (CSEM) is a geophysical electromagnetic method used to detect hydrocarbon reservoirs in marine settings. Used mainly as a derisking tool by the industry, the applicability of CSEM is limited by the size of the target, low-spatial resolution, and depth of the reservoir. Synthetic aperture, a technique that increases the size of the source by combining multiple individual sources, has been applied to CSEM fields to increase the detectability of hydrocarbon reservoirs. We apply synthetic aperture to a 3D synthetic CSEM field with a 2D source distribution to evaluate the benefits of the technique. The 2D source allows steering in the inline and crossline directions. We present an optimized beamforming of the 2D source, which increases the detectability of the reservoir. With only a portion of three towlines spaced 2 km apart, we enhance the anomaly from the target by 80%. We also demonstrate the benefits of using the Poynting vector to view CSEM fields in 3D. Synthetic aperture, beamforming, and Poynting vectors are tools that will increase the amount of information gained from CSEM survey data.

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