AAPG ANNUAL CONFERENCE AND EXHIBITION
Making the Next Giant Leap in Geosciences
April 10-13, 2011, Houston, Texas, USA
The Pony Discovery, Green Canyon Block 468, U.S. Gulf of Mexico: Structural Evolution and Salt Tectonics
(1) Hess Corporation, Houston, TX.
In 2006 Hess Corporation drilled the Pony discovery well in Green Canyon Block 468. A 4-way dip closure in sub-salt Middle and Lower Miocene reservoirs traps reserves at depths near 30,000 feet and extends southward into adjoining blocks. Resources are currently being evaluated through a program of drilling, seismic reprocessing, and detailed interpretation. We combine regional and local transect restorations with regional salt maps and local isochore maps to derive the structural setting and structural evolution of the Pony structure. The structure developed in response to salt tectonics on both regional and local scales which deformed the “primary” section: the section that is in uninterrupted stratigraphic succession above the Louann salt but often below an allochthonous canopy or weld. Regionally, Pony abuts against the structural boundary between interconnected and isolated primary depo-centers. It is among the most landward of interconnected primary depo-centers and fundamentally differs from structural and depositional settings of the isolated depo-centers to the north. It has experienced semi-regional translation and minor shortening, particularly adjacent to a salt stock NE of the field - detached on underlying salt. Strata surrounding the stock were folded into a high which may have been an early focal point for hydrocarbon migration. An adjacent NE-SW elongated salt high, which influenced corresponding stratigraphic variations, developed in the Middle Miocene, possibly as a gentle fold. The structure was later deformed in response to differential movement of underlying salt as it fed the overlying canopy - an amalgamation of salt sourced through multiple stocks. This phase was important for present-day structural configuration and secondary oil migration Post canopy evacuation of deep salt beneath the high was accommodated by at least one large offset fault that strikes NE-SW and cuts the entire basin from canopy to the depleted deep salt layer. Faults in a second set are also post-canopy in age and also strike NE-SW, but tip out with depth. These smaller faults accommodated dip changes associated with “outer arc extension” during turtle formation.