Integrating depositional models, ichnology, and sequence stratigraphy in reservoir characterization: The middle member of the Devonian–Carboniferous Bakken Formation of subsurface southeastern Saskatchewan revisited Solange Angulo and Luis A. Buatois ABSTRACT The Upper Devonian–Lower Carboniferous Bakken Formation is a widespread siliciclastic unit in the subsurface of the Williston Basin that is subdivided into three members: lower and upper organic-rich shale members and a dolomitic, silty, and sandy middle member. Although the unit has become one of the most active oil plays in North America and numerous sedimento- logic studies have been made, no consensus about the deposi- tional environments of the middle member has been achieved. Previous studies suggested several depositional and sequence- stratigraphic scenarios, including lowstand offshore-shoreface, normal-regressive offshore-shoreface, incised estuary, and falling- stage shoreface complexes for the middle member. We propose a new depositional and sequence-stratigraphic model and com- pare it with some previous interpretations. This new model includes a basal transgressive systems tract (TST) embracing shelf deposits, a highstand systems tract comprising shelf to lower shoreface environments, and an upper TST encompass- ing a brackish-water embayment complex and offshore to shelf AUTHORS Solange Angulo  Department of Geo- logical Sciences, University of Saskatchewan, 114 Science Place, Saskatoon, Saskatchewan, Canada S7N-5E2; solange.angulo@usask.ca Solange Angulo is a Ph.D. student at the Uni- versity of Saskatchewan. She obtained her B.S. degree from Universidad Central de Venezuela in 2001. From 2001 to 2006, she worked for Petróleos de Venezuela S.A. Exploration as a sedimentologist. She has received Saskatchewan Energy and Resources, International Association of Sedimentologists, and AAPG grants; Honorable Mention Core Workshop (Canadian Society of Petroleum Geologists); the Wolfgang Stoterau Memorial Award (Canadian Institute of Mining); and the Presidential Award (Open House, Saskatchewan). Luis A. Buatois  Department of Geological Sciences, University of Saskatchewan, 114 Science Place, Saskatoon, Saskatchewan, Can- ada S7N-5E2; luis.buatois@usask.ca Luis Buatois is a professor at the University of Saskatchewan, specializing in paleoenviron- mental, evolutionary, and stratigraphic aspects of ichnology. He is the president of the Inter- national Ichnological Association and former vice president of the International Palaeontological Association. He has conducted field and sub- surface work in many different countries. He has published four books and more than 150 scien- tific articles, and edited three journal issues. ACKNOWLEDGEMENTS We thank Saskatchewan Energy and Resources and the University of Saskatchewan for pro- viding financial support for this project. Additional funds were provided by AAPG (grants 2008, 2009), International Association of Sedimentol- ogists (grant 2009), and Shell Canada. We give special thanks to the Geological Subsurface Laboratory staff in Regina, particularly to Melinda Yurkowski, Chris Gilboy, Erik Nickel, Dan Kohlruss, Chao Yang, Tyler Music, and all the technical team that diligently displayed the cores for this study; without their support, this project would not have been possible. We are also grateful to Robin Renaut for critically reading this manuscript. This project benefited from constructive discussion Copyright ©2012. The American Association of Petroleum Geologists. All rights reserved. Manuscript received March 30, 2011; provisional acceptance August 16, 2011; revised manuscript received September 19, 2011; final acceptance November 2, 2011. DOI:10.1306/11021111045 AAPG Bulletin, v. 96, no. 6 (June 2012), pp. 1017 – 1043 1017