Allochthonous salt sheet growth: Thermal implications for source rock maturation in the deepwater Burgos Basin and Perdido Fold Belt, Mexico

Abstract

A better understanding of suballochthonous salt petroleum systems can be achieved by thermal modeling a series of vertical pseudowell profiles that are positioned along ramps and flats identified at the base salt level. This allows the changing 2D shape of the highly conductive salt to be taken into account and assesses the physical parameters that control the thermal evolution. A case study of a typical cross section through the Burgos Basin and Perdido Fold Belt is analyzed in an area of very active oil exploration in northern Mexico. Numerical experiments indicated how the extrusion of salt cools the underlying basin and significantly prolongs the period of Tithonian source rock maturity. The rapid extrusion of thick allochthonous salt sheets, and the associated transient heat flow effects, can also cause peaks in oil generation, in places postdating the trap formation during the Oligo-Miocene folding event. The principal Tithonian source rock is predicted to have remained in the oil window since Paleogene times, despite being buried to present-day depths of approximately 8 km subsea. This upgrades the oil potential of some of the subsalt areas that are currently on offer in the CNH-R01-L04/2015 Mexico deepwater Licensing Round.