Imaging Deep Gas Prospects Using Multicomponent Seismic Technology

The objective of this research was to investigate the value of long-offset multicomponent seismic data for studying deep-gas geology across the northern shelf of the Gulf of Mexico (GOM). WesternGeco allowed the Bureau of Economic Geology to analyze some of their long-offset, four-component, ocean-bottom-cable (4-C OBC) seismic spec data so the research could be done. These data were processed using source-receiver offsets as large as 10 km. These data represent the largest imaging offsets available for seismic reflection data and should image deeper than conventional seismic reflection data. The P-P mode extracted from the data verifies that sediment accumulations 18 km (60,000 ft) thick occur beneath portions of the seismic grid. This information sets new guidelines for deep geology across the GOM basin. The P-SV mode sometimes images to depths of 13 km (42,000 ft). Previously, no one knew the depth-imaging capability of P-SV data. Both modes, P-P and P-SV, provide good images of geologic conditions to depths of 9 km (30,000 ft), the present deepest depth that most operators wish to drill along the shallow-water, northern shelf of the GOM.