The Paleocene–Eocene of the Gulf of Mexico: A 350-Mile-Long Salt Gravity-Driven Sliding System

Jacques-Antoine Dal¹, Gwenael Guerin¹, and Julian Mather^2
1 Total E&P USA, Inc, Houston, TX
² Total E&P Angola, Luanda, Angola

The Paleocene-Eocene play has been explored for decades onshore Texas and Louisiana, in a deltaic depositional environment. Recently, exploration wells have drilled important thicknesses of turbiditic sands in the deep water Gulf of Mexico, within foldbelts 350 miles south-eastwards of the deltas.

Our interpretation, integrating salt deformation processes and analogs from other gravity-driven systems, suggests that these hydrocarbon plays correspond to the edges of one of the most extended gravity-driven deformation systems over a salt decollement ever described, extending over 350 miles. It can be divided into: - a narrow extensional domain located onshore, containing the Wilcox depocenters developed along growth faults and limited by the shelf breaks which are parallel to the present day shoreline; - a broad compressional domain from the present day Louisiana - Texas shelf to the deep offshore foldbelts. Seismic data shows many contractional features on the shelf, which were once close to the base of slope, and also in the basin, were there are windows of seismic visibility subsalt. Seismic and well data also reveal the presence of condensed Paleogene slabs above salt, interpreted as former Paleogene anticlines or plateaus and incorporated as allochthonous rafts within the canopy. In the foldbelts, the toe of the domain is characterized by subtle salt-cored anticlines.

As most of the contractional domain is deeply buried or below the Tertiary salt canopy, the seismic imaging is often challenging and therefore the structural and sedimentological continuity is difficult to assess, leaving many uncertainties regarding the deformation timing and sand distribution.