Restorations of faulted domes

Abstract

We illustrate recently developed techniques of three-dimensional (3-D) geomechanical structural restoration applied to resolve the kinematics of deformation in the sedimentary cover above mobile salt. Our study area is one of the hydrocarbon-bearing domes in eastern Arabia. We used 3-D seismic reflection and well data to build a 3-D structural geomodel for the well-imaged part of the sedimentary cover. The geomodel includes faults and a 3.2-km (2-mi) thick section of Permian to Cenozoic sediments and is restored from the Jurassic to the present day. The development of the structures is characterized by stages of normal faulting in the Jurassic and Cretaceous and a subsequent stage of low-amplitude folding in the Late Cretaceous. We interpret that the development of the structures in the sediment cover is caused by the movement of a deep, nonpiercing salt pillow. The structures grew under the control of gradually changing deforming mechanisms, from dominantly faulting to folding. The transition from normal faulting to domal folding is indicative of a reactive salt diapir. These restoration results improve our understanding about the kinematic history of the structures developed within the Jurassic and Cretaceous sedimentary section, which contains most of the hydrocarbon resources in Arabia. Moreover, they illustrate the potential of geomechanical restoration methods to investigate structures above mobile salt systems.