Steve H. Hall¹
(1) BP Amoco, Houston, TX

Abstract: The Development of Large-scale Sub-salt Structures in the Deep-water Western Gulf of Mexico

An exciting new structural model, based upon regional Gulf of Mexico structural analysis, has been developed for the western Gulf of Mexico. This model has lead to the recognition and prediction of large scale structures.

Deep-water Gulf of mexico structuring is invariably controlled by autochthonous salt movement. Evidence suggests that most of the deep-water was underlain by an inflated autochthonous salt layer during the Cretaceous to middle Miocene. Partial deflation of this layer during Plio-Pleistocene sedimentation, has lead to the development of potentially large sub-salt structures in the north and the emplacement of the Sigsbee canopy to the south. The position of structures is possibly controlled by NW-SE trending basement lineaments. Structures could be folds, thrusts or extensional in nature. Salt feeder systems have developed from the crests of structures, thus most are located sub-salt. Structures are complicated by the development of deep welds.

Common subsidence histories suggest that basins tend to develop as primary basins. A positive factor of this model is that structures include Mesozoic source rocks. Regionally reservoir is relatively low risk, but the development of good quality sands over deep structure is difficult to predict with the available seismic database.

Using this model as an exploration driver affords considerable opportunity for growth in the Western Gulf. The main challange is to develop improved quality depth seismic so as to image not only the sub-salt structures but also the sub-salt reservoir potential.

AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana