Petroleum Systems of Deep-Water Basins - Gulf Coast Section SEPM

Subsalt Exploration Trap Styles, Walker Ridge and
Keathley Canyon Areas, Deep Water Gulf of Mexico
Louis Liro
e-mail: louis_liro@veritasdgc.com
Nathan Weber
Steve O’Hara
Mo Etemadi
Susan Lock Williams
Mary Cubanski
Veritas Exploration Services
Veritas DGC
10300 Town Park
Houston, Texas USA 77072
Mary Kadri
Veritas Exploration Services
2200, 715–5 th Avenue S.W.
Calgary, Alberta Canada T2P5A2
Peter Montecchi
retired
Abstract
We describe the exploration plays associated with the salt nappe, canopy, and massif systems of Walker Ridge and
Keathley Canyon areas in the deep water Gulf of Mexico. Depth imaging of 3D seismic allows definition of the salt
emplacement and deformation history, and the associated subsalt trap styles.
Salt emplacement in the region follows a simple history: relatively evenly spaced inferred paleo salt stocks have
fed salt canopy, nappe, and massif systems. In this region, salt is emanating directly from the Jurassic Louan layer.
Mapping of the salt allows division of the present–day salt masses into discrete salt “cells.” Emplacement and extrusion
occurred in a series of low-angle and high-angle surfaces, dominantly lateral in the canopy and nappe systems,
and dominantly vertical in the massif system.
Subsalt structural traps are divided into three major types, from deepest to shallowest: (1) Anticlinal salt–cored
folds of Mesozoic and Paleogene strata; (2) Structural inversions (“turtles”) of Paleogene and Neogene strata; and (3)
Counterregional dip and truncation of Neogene strata against the vertical salt emplacement to lateral salt emplacement
transition. Mesozoic anticlines are located basinward of a regional low in the Middle Cretaceous sequence
boundary. These structures are fully detached from the superjacent lateral salt masses. These structures are on–trend
with recent significant discoveries in more shallow waters. Structural inversions are associated with paleo salt stocks.
Salt truncation traps are more shallow and offset from the crest of the inversion structures. Definition of salt “cells”
allows an understanding of the development of each structure in the trend, which may imply subtle differences in
structural timing and trap competency prior to hydrocarbon emplacement.
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