Continuing Insights into Structure and Stratigraphy of the Onshore Gulf Basin from Prestack Depth Imaging of Mega-Regional Strike Lines from South Texas to the Florida Panhandle

摘要

Mega-regional 2D prestack depth migrated (PSDM) strike lines can provide advances to the interpretation of the onshore Gulf Basin framework. Continuous seismic lines with consistent depth processing across nearly the full extent of the onshore portion of the basin allow onshore depocenters, structural axes, and canyons to be seen in their regional context. Plays dependent on new horizontal wells can be tied from west to east around the basin and clearer relationships established. In addition, potential extrapolations of existing plays can be interpreted. A preliminary interpretation is presented of an initial version of a key composite strike line that is made up of 41 legacy 2D lines and PSDM processing by ION Geophysical. This mega-regional line is 714 mi (1149 km) long. Its location is highlighted on the included index map which also shows the location of the entire Gulf of Mexico framework seismic program (Fig. 1). This is one of a series of seven composite strike lines of approximately 8500 mi (13,679 km) and 380 individual line segments that ranges from a line hugging the coast to the northernmost line which traverses the East Texas Salt Basin, Sabine Uplift, North Louisiana Salt Basin, Mississippi Interior Salt Basin, and Wiggin's Arch to the Florida Panhandle. The strike lines tie together with existing megaregional dip lines and the survey spans across the basin from South Texas to Alabama and from the northern limit of the onshore Gulf Basin to the abyssal plain. The dip lines in some cases have been extended landward to tie the new strike grid. The interpretation has been tied to well control with a series of synthetics and check shot surveys and a comprehensive database of well tops. Geologically,the key line highlighted in Figure 1 is located approximately along the Cretaceous shelf edge and extends from the U.S.-Mexico border on the southwest to the Louisiana-Mississippi border on the east end of the line. The entirety of the seismic data is shown in Figure 2 along with selected horizons, major structural features and the location of some current plays of interest. Jumps in the seismic reflections along the line indicate gaps that could not be filled in with existing seismic data. The displayed line had four synthetics constructed on it which were provided to the processors for velocity control and used to tie well control to the data. All four synthetics provided a good tie to the interpreted horizons and one of those synthetics is shown on the line (Fig. 2).