Michael J. Roberts¹, Seamus G. Reilly¹

(1) Chevron North America Exploration and Production Co, New Orleans, LA

ABSTRACT: Frontier Exploration on the Abyssal Plain of the Deepwater Gulf of Mexico: Syn-Rift through Passive Stage Mesozoic Objectives Identified

The abyssal plain of the Gulf Of Mexico (GOM), defined here as areas basinward of the Mississippi Fan and Perdido Foldbelts, has been described as a featureless plain devoid of significant structuring and underlain by oceanic crust. A regional examination of the province cast doubt on this benign history and revealed a complex structural province with a multitude of exploration possibilities. This study focused on the Mesozoic where opportunities within the syn-rift Middle to Late Jurassic through passive stage Middle Cretaceous have been identified and leased. Potential Jurassic play types include alluvial deposits feeding lacustrine basins; shallow marine siliciclastics and carbonates onlapping exposed basement; low-relief salt rollers with eolian to shallow marine deposits in structural traps, and aprons surrounding fault-bounded basement blocks. Cretaceous age plays include isolated carbonate platforms and associated facies and patch reef environments. Adoption of a simple-shear rift model to the GOM provides a plausible explanation for the distribution of modeled continental fragments and the potential for associated non-marine to shallow marine reservoir facies. The major geologic uncertainties are the presence and thermal state of potential source rocks and the preservation of original fabric supported porosity. This regional study utilizes geologic analogs, potential-field data, regional temperature and porosity trends, 2-D regional seismic grids and portions of several speculative 3-D surveys. Significant engineering and economic hurdles remain in this emerging domestic frontier which lies in water depths approaching 10,000' with total prospect depths at or below 30,000'.

AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado