Optimized 3D synthetic aperture CSEM

Locating hydrocarbon reservoirs has become more challenging with smaller, deeper or shallower targets in complicated environments. Controlled-source electromagnetics (CSEM) is one geophysical method used by industry to find and derisk reservoirs in marine settings. The diffusive nature of CSEM fields means the signal from the target is only a small part of the total field. To reduce the impact of the complicated settings and improve the detecting capabilities of CSEM, we apply synthetic aperture to CSEM data. Synthetic aperture virtually increases the length and width of the CSEM source by combining the responses from multiple individual sources. Applying a weight to each source steers or focuses the synthetic aperture source array in the inline and crossline directions. We introduce an optimization method to find the optimal weights for synthetic aperture arrays that adapts to the information in the CSEM data. To demonstrate the benefits of weighted synthetic aperture, we apply a 2D synthetic aperture array and a crossline only synthetic aperture array to noisy, simulated electromagnetic fields. Both synthetic aperture arrays reduce the noise and increase the anomaly from the reservoir. The crossline only synthetic aperture array also preserves the structure of the model.