Chronostratigraphic Relationships of the Woodbine and Eagle Ford Groups across Texas

Abstract

Four depositional sequences (allomembers), each geochemically, petrophysically, and chronostratigraphically distinct, were defined within the outcrops and shallow subsurface of the Eagle Ford Group in West Texas. The lower two depositional sequences occur within the Lower Eagle Ford Formation, while the upper two depositional sequences occur within the Upper Eagle Ford Formation. These four depositional sequences can be correlated into the subsurface of South Texas to get an understanding of the distribution and thickness variations of each chronostratigraphic unit within the Eagle Ford Source Rock Play Fairway. The four depositional sequences can also be correlated into the East Texas Basin in order to gain an improved understanding of the chronostratigraphic relationships between the Eagle Ford and Woodbine groups in this basin. The regional sequence stratigraphic correlations indicate that the Eagle Ford Group of West and South Texas, including the Lower and Upper Eagle Ford formations and the four depositional sequences contained within, can be correlated into the outcrops and shallow subsurface of the Eagle Ford Group along the western flank of the East Texas Basin. These correlations also indicate that the Woodbine Group is an older chronostratigraphic unit that is generally absent in South and West Texas due to erosion and/or non-deposition.

AAPG Datapages/Search and Discovery Article #90219 © 2015 GCAGS, Houston, Texas, September 20-22, 2015