3D sequence stratigraphy in the Gulf of Mexico
Introduction
An extensive 3D sequence stratigraphy analysis was carried out by Benoît Reymond on a survey from West Cameron, offshore Louisiana. This was the first time that such a study was undertaken using 3D seismic data, which proved to be far superior than 2D data in highlighting parasequences. For instance, 20 sequences were defined in the Plio-Pleistocene where only 14 were known previously.
In a clastic shelf environment such as offshore Louisiana (northern Gulf of Mexico), it becomes possible to directly infer the sedimentation facies from the lateral variations in seismic reflection along a time consistent reflector interpreted on the entire surface of a 3D survey. These amplitude anomalies observed along a flattened horizon enhance subtle and continuous geological objects (inferior to 20 m) invisible on the vertical seismic lines. Successive paleosurfaces of sedimentation can be reconstructed every 4 milliseconds (every 4 m in the subsurface, 0-2500 m) and show the vertical evolution in the deposition conditions through time and space.
Location map of the West Cameron 3D seismic survey, with salt domes represented in black. the studied area corresponds also to the main Lower Miocene depocenter.
