Sparse-Layer Inversion as a Tool to Delineate Thin Sandstones, Lower Magdalena Valley Region, Colombia: A Case Study
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Abstract
Recent oil and gas exploration in the Lower Magdalena Valley, Northern Colombia, has shown the presence of gas in the Lower Porquero shale formation. The existence of thin hydrocarbon-filled reservoir sandstones below seismic resolution can explain the seismic response. To test this hypothesis, seismic response is modeled near existing wells and compared with high-resolution data generated by a sparse-layer reflectivity inversion, constrained by high-resolution spectral decomposition, applied to conditioned pre-stack seismic data from the La Creciente block at northern Magdalena region of Colombia. Seismic-data-conditioning algorithms, such as structural and radon filtering, were tested, calibrated, and applied to the pre-stack seismic gathers as a preliminary step before implementing the sparse-layer reflectivity inversion. Removal of incoherent noise and processing artifacts is crucial prior to the application of the sparse-layer seismic reflection inversion to guarantee high-quality results whilst preserving AVO behavior and honoring existing faults. The increased frequency bandwidth and improved resolution allowed the detection of events previously not seen on the seismic data that may delineate unexplored potential gas reservoirs.