Petroleum Systems of Deep-Water Basins - Gulf Coast Section SEPM
Petroleum Systems of Deep-Water Basins - Gulf Coast Section SEPM
Petroleum Systems of Deep-Water Basins - Gulf Coast Section SEPM
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Late Mesozoic and Cenozoic Deposystem Evolution<br />
in the Eastern <strong>Gulf</strong> <strong>of</strong> Mexico:<br />
Implications for Hydrocarbon Migration<br />
Richard H. Fillon<br />
Earth Studies Associates<br />
3730 Rue Nichole<br />
New Orleans, Louisiana 70131<br />
e-mail: fillorh@bellsouth.net<br />
Abstract<br />
A preliminary analysis <strong>of</strong> Mesozoic and Cenozoic deposystems in the eastern <strong>Gulf</strong> <strong>of</strong> Mexico, using published<br />
regional stratigraphic and depth to basement studies, reveals striking elements <strong>of</strong> deposystem history and petroleum<br />
system architecture. Integration <strong>of</strong> thirteen regional studies into a single chronostratigraphic framework provides a<br />
basis for assessing accumulation rates within eight provisional Late Mesozoic second-order depositional sequences<br />
and eight Cenozoic second-order depositional sequences spanning the interval 165 Ma to the present.<br />
Interval accumulation rate mapping reveals that major deposystems shifted in response to the changing tectonic<br />
setting <strong>of</strong> the <strong>Gulf</strong> basin. The evolving deposystems reflect changes in sequence architecture corresponding to evolution<br />
from a dynamic environment <strong>of</strong> salt tectonics and hot mobile crust in the youthful <strong>Gulf</strong> basin to cool thermally<br />
stable modern crust where gravity driven depositional patterns dominate. Shifting depocenters throughout this period<br />
differentially loaded and compacted underlying sediments, thus modifying pressure gradients that influence the lateral<br />
migration pathways <strong>of</strong> hydrocarbons. Analysis <strong>of</strong> differential deposystem loading predicts that hydrocarbon migration<br />
paths locally converge within the original Federal lease sale 181 area, principally because Late Cretaceous strata<br />
in the area are relatively thin compared to adjacent areas. While perceived hydrocarbon risk is therefore diminished,<br />
low accumulation rates for most sequences suggest that reservoir risk in a given vertical section is high. The search for<br />
productive reservoir in the area should therefore focus on specific parts <strong>of</strong> the section immediately above or below a<br />
condensed Middle Cretaceous Sequence Boundary (MCSB) interval that exhibit accumulation rates higher than the<br />
regional average. Accordingly, the late Albian-early Cenomanian (Paluxy sequence) and the middle to late Miocene<br />
(upper Miocene sequence) are preferred candidates for exploration.<br />
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