Structural Trap Development and Basin Modeling in North-Central Gulf of Mexico Deepwater Subsalt Plays

Mount, Van S.¹; Mentemeier, Samuel H.¹; Mahon, Keith I.^1
1 Anadarko Petroleum Corp., Houston, TX.

The structural development of traps targeted in north-central Gulf of Mexico (GoM) deepwater subsalt plays (both Miocene and Early Tertiary age reservoirs) involves interaction between sedimentation and salt movement. Trap development and timing are typically related to subsidence of sedimentary depocenters into an underlying autochthonous salt layer, and emplacement of a salt canopy at a shallow structural level, commonly near the seafloor. Canopy emplacement occurs by movement of salt from the deep autochthonous layer, through a salt stock feeder system, to the shallow canopy level, where it flows laterally. Subsalt 3-way dip-closed traps develop against salt feeders on the periphery of depocenters, and subtle 4-way dip-closed traps are typically observed in the central portions of depocenters. Prospect to semi-regional scale transects, restorations, and maps based on 3D seismic from the north-central GoM deepwater province are used to illustrate trap formation through its entire history (pre-, syn-, and post-canopy emplacement). The examples demonstrate that understanding the development of the trap, as well as, the depocenter in which the trap resides, are critical input for basin models used to assess components of geologic risk associated with subsalt prospects in the north-central deepwater GoM.

AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009