ABSTRACT

One-dimensional, steady state, thermal maturation modeling was conducted at sixteen pseudo-well locations along two profiles in the Perdido fold belt, Alaminos Canyon OCS protraction area. Modeling results apply to strata basinward of the Sigsbee Escarpment; models were not conducted for subsalt areas.

Geochemical fingerprinting of oil seeps in the Perdido area indicates possible source intervals of Upper Jurassic (Tithonian) and Eocene age. The initial results of thermal maturation modeling suggest that Upper Jurassic to middle Eocene strata presently lie within the oil generation window. Other potential source rocks (Oxfordian, Barremian, and Turonian) each lie within the peak oil generation window but at different locations in the fold belt. Possible Eocene source rocks lie within the early oil generation window in the basinward (southeast) half of the fold belt.

Burial history charts for each location relate the timing of source bed maturation to fold belt (trap) formation. Strata within the oil window can vary greatly from fold crest to adjacent syncline. At most locations, the possible Oxfordian source passed through peak oil generation during the Oligocene to Miocene, after fold belt formation. Potential Tithonian, Barremian, and Turonian source rocks did not enter peak oil generation until the Miocene to Present, or have yet to reach peak oil generation on some fold crests. Possible Eocene source rocks have not reached peak oil generation anywhere in the Perdido fold belt.

Differences in depth of burial and structural uplift at each location account for most of the variability observed in the maturity modeling. The expected influence of underlying autochthonous salt (i.e. elevated heat flow) is partially negated by assumptions in the steady state heat flow model. Thus, our modeling may underestimate the true thermal maturity of source rocks in the Perdido area.