ABSTRACT

Along with the tremendous increase in seismic activity in deep water areas of the Gulf of Mexico, the use of high-resolution gravity and magnetic data has also increased dramatically. The proper application of these data can result in enhanced seismic velocities, truly integrated geologic models, and decreased exploration risk.

Using new interpretation case studies from the TGS-CALIBRE Geophysical Company Deep Water Reconnaissance Program (TGS Phase 45), the utility of incorporating gravity constraints on deep water interpretations can be clearly demonstrated. Since the Phase 45 program is comprised of long regional lines, a clearer view of the deep regional structure may also be interpreted from the data.

The acquisition of high-resolution gravity and magnetic data, in conjunction with both 2-D and 3-D seismic surveys, has now become a standard procedure in the Gulf of Mexico. Several hundred OCS blocks of high-resolution gravity and large areas of high-resolution aeromagnetic data have been recently acquired and more acquisition is in progress. The use of high-resolution gravity in seismic velocity analysis and the use of velocity grids for localized, focused density input to gravity models are now commonly used. A brief review of instrumentation, costs, and integrated workstation software applications is provided to set the framework for the interpretation case studies. A detailed example of an integrated interpretation of a localized salt feature is provided from the Phase 45 area.

Workstation applications now in use facilitate the direct transfer of data and models between seismic and gravity/magnetic modeling software systems. A demonstration of these tools is included in the presentation.