Prestack depth imaging in the eastern Gulf of Mexico

Abstract

The Gulf of Mexico (GOM) shelf is one of the most thoroughly explored regions in the world. As downstream technology has advanced, exploration and production of hydrocarbons have progressively moved into waters greater than 3500 ft in the central GOM. On the other hand, the eastern GOM is largely underexplored. It is now attracting industry attention because the Minerals Management Service of the U.S. Deparment of the Interior has scheduled OCS Lease Sale 181 for December 2001. Previous investigations of the eastern GOM structural geology (e.g., Wu, 1990; DeBalko and Buffler, 1992; Dobson and Buffler, 1997) were based on 2-D time-processed seismic data with no tying well information. Approximately 3270 miles of 2-D seismic data were recently gathered over the Lloyd Ridge and DeSoto Canyon areas to evaluate the region's hydrocarbon potential for the upcoming lease sale (Figure 1). Most data were acquired in the deepwater Florida basin, but a small portion overlapped the basin/shelf boundary and the outermost portions of the Florida shelf. The region is geologically complex. It contains interbedded salt, a history of vertical and lateral salt movements, and the juxtaposition of dramatically varying lithology and velocity across the steep shelf slope feature known as the Florida Escarpment. Figure 1. Map of study area. Test line in red. The geologic and geophysical complexity of this area, limited previous exploration activity, and lack of well data present many challenges to developing an accurate image and understanding of the region. Due to the subsurface complexity, interpretation remains ambiguous, even when using these recent time data, because prestack depth migration (PSDM) has been shown to provide superior subsurface imaging in other parts of the GOM (Willacy, 1999). The authors elected to evaluate its effectiveness on these new data. If the test were to prove successful, depth imaging across the lease area might …