Kelly Hattori

presents

A new sequence stratigraphic framework for the Early Cretaceous Pettet Formation of East Texas and investigation of controls on facies deposition

BIOGRAPHY

Kelly is a carbonate stratigrapher employed by the UT Austin Bureau of Economic Geology's State of Texas Advanced Resource Recovery (STARR) research group. Kelly holds a M.S. degree in Geosciences from the University of Texas at Austin and B.S. degrees in Geology and Marine Biology from the University of North Carolina at Wilmington. Her early research focused on sequence stratigraphy and paleoecology of coral reef systems, particularly with respect to global and local ocean perturbations such as ocean anoxic events and ocean acidification. She now broadly works Gulf Coast Cretaceous carbonates with a focus on salt-sediment interactions within the East Texas Basin, where she examines the sometimes-conflicting relationship between halokinesis and traditional sequence stratigraphy as well as the impact of halokinetic topography on carbonate depositional systems.

ABSTRACT

The Pettet Formation of East Texas consists of major platform-building carbonates that were deposited during the Early Cretaceous on the land-attached Comanche Platform in the northern Gulf of Mexico. Growth of a reef margin that persisted for millions of years facilitated development of a rimmed platform architecture with an expansive shelf interior over 200 kilometers wide. Within the shelf interior, reservoirs formed by oolitic-skeletal shoals have been targeted for conventional production for the better part of a century. Shoal distribution on the shelf is affected by numerous topographical features such as intrashelf basins and uplifts, as well as influx of siliciclastic sands in nearshore environments. In East Texas, reservoir facies distribution is further complicated by the influence of the East Texas Salt Basin, which contained numerous salt domes and salt withdrawal minibasins at the time of Pettet deposition.

Although work in the central Texas region has established a sequence stratigraphic framework for the time-equivalent Sligo Formation, to date no comprehensive work has been done to document cyclicity, architecture, and facies distribution of this formation in East Texas. This study aims to rectify this gap by establishing a core-calibrated stratigraphic framework for the Pettet Formation in the East Texas region. Establishment of a framework allows improved recognition of reservoir facies distribution and continuity. Furthermore, a clearly-defined framework aids in searching for missed opportunities, particularly in the East Texas Basin where the interplay of eustacy and halokinesis and their effects on facies distribution and transport remains poorly understood. To better understand the impact that local controls (e.g. subsidence and halokinesis) had on the Pettet depositional setting, we compare profiles across three counties in East Texas and highlight key differences in facies architecture.