Integrating Physical Models and 3D Seismic: Geometry and Kinematic Analysis of Contractional Structures Above a Salt Detachment

Richard Kilby
University of Texas at Austin, Jackson School of Geosciences
Austin, Texas
Richard.Kilby@mail.utexas.edu

Deep-water fold belts are attractive exploration targets in many of the world’s salt basins. Prime examples are the Gulf of Mexico and the Atlantic margins, especially the Lower Congo Basin. Accurately defining the structural style and reservoir distribution in these belts is important to successful exploration. So, too, are studies that go beyond seismic interpretation.

This study integrates a suite of physical models with the structural interpretation of a 3D seismic volume. The study area in deep-water southern Gabon includes the northern distal margin of the immense Congo Fan. The seismic volume images a gravity-driven fold belt detaching above salt. Models designed on the basis of structures observed in seismic profiles and slices help us understand patterns of anomalous stratal onlap and wedging. Models also illustrate kinematic evolution and guide structural restoration of the natural structures.

Physical models in our study include two series of experiments, both of which involve synkinematic sedimentation at variable rates : (1) shortening above a flat basal detachment and (2) shortening superposed on low-amplitude precursor salt anticlines. Models are digitally photographed and animated to capture the detailed evolution of the fold-and-thrust belt. Coupling scaled physical models with 3D seismic interpretation provides additional constraints on structural style, deformation history, and salt movement through time than those available through seismic interpretation alone.