HIGH-RESOLUTION 3D SEISMIC DATA: INSIGHTS INTO THE DEFORMATION OF HETEROGENEOUS LAYERED MATERIALS

The fundamental requirement for economic success in the upstream of the hydrocarbon industry is accurate definition of trap geometry, evolution, integrity, charge, and producibility. 3D seismic reflection data define subsurface structural geometry with the highest resolution of any available and practical technology, and so are the primary basis for elements of trap analyses at both seismic and subseismic scales. 3D seismic data define trap geometry relatively directly, by conversion of the time data to depth. Trap evolution is defined from the kinematic history that is typically recorded by syntectonic strata and unconformities, a record that is provided by 3D seismic but is typically missing for structures exposed at the earth's surface. Trap integrity and producibility can depend on the fluid-flow properties of faults and fractures, which are commonly inferred from kinematic and mechanical modeling of rock deformation, at seismic and sub-seismic scales, based on geometry observed on 3D seismic. Trap charge is estimated by modeling the burial history of source horizons and inferring migration pathways, based on 3D seismic geometry and geodynamic analysis. All these elements of trap analysis overlap with the interests of academic structural geologists: describing structural deformation and understanding what controls it. Several examples of structural insights provided by 3D seismic data will be described in this presentation, from areas of detached extension and contraction, “infinitesimal” strike-slip, and multiple deformation. These examples illustrate insights derived from readily resolvable geometry on “good” seismic data using standard and proprietary volume-interpretation techniques. The primary challenges for structural geologists interpreting seismic volumes are to fill in the areas of “bad” data and to characterize structural features which may be key to predicting fluid flow (e.g. fractures and faultzone materials), but are too small to resolve,. For nearly 50 years, kinematic analysis has been the preferred approach to these challenges, because it is a cost effective, easily implemented (albeit theoretically “wrong”!) method for predicting geometry and strain. Mechanical analyses promise to improve these predictions, once the burdensome implementation and difficulty in prescribing constraining parameters are overcome.