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High salt concentrations and small targets in complicated geology often found in the Gulf of Mexico have been an impediment to the application of marine CSEM techniques, until recent advances in operations, acquisition hardware and advanced processing techniques permit 3D-mapping of complex resistivity distributions. Using two examples from a recent prelease sale campaign, we demonstrate the successful application of the entire value chain from customized acquisition grids, multi-frequency acquisition to processing of data including wide-azimuth lines with reliable phase and amplitude, and subsequent inversion-based 3D interpretation. Advanced interpretation is based on an iterative Hessian-based inversion with quasi-Newton update and fast finitedifference time-domain modeling. Inversion results are used to construct resistivity distribution consistent with 3D-seismic images. During the campaign, we successfully addressed the client’s need to resolve small targets (2 km x 2 km) with low-resistivity pay (Δρ < 5 Ωm), many found in the vicinity ( |
