Thermal maturation history of the Wilcox group (Paleocene-Eocene), Texas: Results of regional-scale multi-1D modeling

By: , and 
Edited by: Lorcan KennanJames Pindell, and Norman C. Rosen

Links

Abstract

The thermal maturation history of the Paleocene-Eocene Wilcox Group has been reconstructed based on burial history models of 53 wells in the Texas coastal plain. This modeling study has been conducted in conjunction with a geologically based assessment of the oil and gas resources in Cenozoic strata of the Gulf of Mexico coastal plain and state waters. In the onshore Texas coastal plain, coals and organic-rich shales, predominantly of terrestrial origin, within the Wilcox Group are the primary source of oil (Wenger et al., 1994) as well as a source of gas. The Wilcox, however, is modeled as a single unit, without subdivision into source rock and non-source rock intervals.

Generation of oil from Type III kerogen within the Wilcox Group is modeled using hydrous pyrolysis reaction kinetic parameters (Lewan, M.D., written communication, 2006). Gas generation from Type III kerogen is represented using calculated Ro values. The models are calibrated with bottom hole temperature (BHT), and vitrinite reflectance (Ro %) data for the Wilcox Group. Ro data from near-coastal sites have been selected to minimize the possible effects of uplift and erosion and then composited to give a regional Rodepth trend.

Model calculations for the study area, the onshore Texas coastal plain, indicate that downdip portions of the basal Wilcox had reached sufficient thermal maturity to generate hydrocarbons by early Eocene (~50 Ma). This relatively early maturation is explained by rapid sediment accumulation in the early Tertiary combined with the reaction kinetic parameters used in the models. Thermal maturation increases through time with increasing burial depth and temperature, gradually moving the maturation front updip. At present day, hydrocarbon generation is complete in the downdip Wilcox within the study area but is currently ongoing in the updip portions of the formation.

Additional publication details

Publication type Conference Paper
Publication Subtype Conference Paper
Title Thermal maturation history of the Wilcox group (Paleocene-Eocene), Texas: Results of regional-scale multi-1D modeling
Series number 27
ISBN 978-0-9836096-3-6
DOI 10.5724/gcs.07.27.0714
Year Published 2007
Language English
Publisher SEPM Society for Sedimentary Geology
Description 30 p.
Larger Work Type Book
Larger Work Subtype Conference publication
Larger Work Title The Paleogene of the Gulf of Mexico and Caribbean basins: Processes, events, and petroleum systems
First page 714
Last page 743
Conference Title 27th Annual Gulf Coast Section SEPM Foundation Bob F. Perkins Research Conference
Conference Location Houston, TX
Conference Date December 2-5, 2007
Country United States
State Texas