Wednesday, November 28
The Petroleum Club of Houston
1201 Louisiana Street, Houston, TX
- The top floor of Total Building
- Access to the Downtown tunnel system
Social 11:15 AM, Luncheon 11:30 AM- 1:00 PM
Cost: $35 pre-registered members; $40 for non-members/ALL walk-ups;
$35 for Emeritus/Life/Honorary; $15 for HGS student members if pre-registered and pre-paid.
To guarantee a seat, you must pre-register on the HGS website and pre-pay with a credit card. You may walk up and pay at the door if extra seats are available. Please cancel by phone or email within 24 hours before the event for a refund. Online & pre-registration closes Wednesday, November 28 at 5:00 AM
Speaker: Arthur Donovan, TAMU
Unraveling the Secrets of the “Eaglebine”: Using Sequence- and Chemo-Stratigraphy to Differentiate Unconventional Plays and Play Fairways within the Woodbine and Eagle Ford Groups in the East Texas Basin
Along the western flank of the East Texas Basin (Figure 1), the Latest Early Cenomanian to Earliest Middle Cenomanian Woodbine Group and Late Middle Cenomanian to Latest Turonian Eagle Ford Group are mapped (Adkins and Lozo, 1951) as distinct unconformity-bounded chronostratigraphic units (Figure 2). In the outcrops and subsurface near Waco Texas (Figures 3 & 4), the Woodbine Group consists of argillaceous and organic-poor mudstones, which transition both vertically and laterally into more sandstone-prone strata into the subsurface and outcrops to the east and north. These Woodbine mudstones have distinctive low to moderate gamma-ray and low resistivity values on geophysical logs (Figure 4). Across the outcrop belt (Figure 3) as well as in the subsurface (Figure 4), Woodbine strata are unconformably overlain by high gamma-ray and resistivity, organic-rich calcareous mudstones in the basal portions of the Lower Eagle Ford Group. The Lower Eagle Ford Formation is overlain by the more carbonate-prone strata in the basal portions of the Upper Eagle Ford Formation, the base of which is marked by a distinct decrease in gamma ray values, driven by a decrease in Uranium content (Figures 3 & 4). The positive δ13C excursion, associated with the OAE2, as well as the base Turonian, also occurs in the basal portions of the Upper Eagle Ford Formation in the outcrops near Waco (Figure 3) and elsewhere across Texas (Donovan and others, 2016).
In the southern subsurface portions of the East Texas Basin, however, a great deal of confusion exists as to what constitutes the Woodbine and Eagle Ford Groups, leading to the common subsurface practice of simply referring to entire succession as the “Eaglebine” (Figure 5). This confusion, however, is largely a result of the common subsurface practice of referring to every sandstone-prone interval between the Buda and Austin, as a Woodbine Sandstone (Figure 5). The net effect of this approach results in having Middle Turonian-aged “Woodbine” Sandstones occurring stratigraphically above Middle Cenomanian to Middle Turonian mudstones, which are included within the Eagle Ford Group in outcrops along the western margin of the basin.
An integrated sequence- and chemo-stratigraphic framework, which stresses chronostratigraphic-surfaces over time-transgressive lithofacies, demonstrates that the unconformity-bounded Woodbine and Eagle Ford Groups, as defined in outcrops along the western margin of the basin, can also be differentiated and mapped in the subsurface of the East Texas Basin. Employing this integrated sequence stratigraphic approach: 1) permits consistent outcrop-to-subsurface correlations of the Woodbine and Eagle Ford Groups across the East Texas Basin; 2) allows improved chronostratigraphic paleo-geographic mapping, as well as improved depo-center delineation through time; and 3) provides a clear chronostratigraphic framework to define Cenomanian and Turonian source rock and tight rock plays and play fairways within the study area. Within this chronostratigraphic framework, the Late Middle Cenomanian organic-rich Lower Eagle Ford Source Rock Play can be defined and mapped in the southwest and southern portion of the basin (Figure 6). The distribution of this source rock play is controlled by onlap onto the physiographic relief of the depositional shelf and seafloor breaks associated with the down-dip limits of the underlying Early Cenomanian to Earliest Middle Cenomanian Woodbine (Freestone) Delta, whose associated (northerly derived) shoreline and fluvial plays are also controlled by the downdip limits of the same depositional shelf break. Finally, this framework finally permits the clear delineation of the paleogeography of the Upper Eagle Ford, Turonian-age, Harris Delta Complex, which progrades into the basin from its southeast margin.
Dr. Art Donovan received his PhD at the Colorado School of Mines in 1984, where his dissertation research was one of the pioneering efforts to apply sequence stratigraphic concepts to outcrops and the shallow subsurface. Upon graduation, he took a position with Exxon Production Research Company where had the opportunity to conduct and manage sequence and seismic stratigraphic studies from basin around the world, as well as conduct research and training for Exxon. In 2000, Art left ExxonMobil to work for BP. At BP, he served sequentially as 1) the Sed/Strat discipline lead, 2) a member of the Global Exploration Assurance Team, and 3) Senior Geoscience Advisor for BP’s Global Unconventional Exploration/Appraisal Efforts. During his time at BP, he led their entry into the Eagle Ford Play in South Texas, as well as well as their research activities on the coeval outcrops in West Texas. During his career in the oil and gas industry, Art published numerous articles on the basics and utilization of sequence stratigraphic concepts, as well as taught and led sequence stratigraphic short courses, and field seminars, for GSA, AAPG, SEPM, & The Geological Society.
After retiring from BP in 2016, Art joined the Department of Geology and Geophysics at Texas A&M University (TAMU) as a full-time faculty member. His research and teaching focus is centered on explaining and predicting the distribution, thickness, and effectiveness of conventional and unconventional reservoirs across their respective play fairways. At TAMU, Art is also the Director of the Unconventional Reservoirs Outcrop Characterization (UROC) Consortium, whose twin missions are to 1) train the next generation of geoscientists for the oil and gas industry and 2) bring the outcrop equivalents of key unconventional plays into the 21st century using modern petro-physical, chemo-stratigraphic, chrono-stratigraphic, and sequence stratigraphic techniques. Presently the UROC Consortium is focused on outcrop and subsurface studies of the Early Permian Unconventional Reservoirs in the Permian Basin, as well as Late Cretaceous Unconventional Reservoirs across Texas.