Copyright by Kurtus Steven Woolf 2012 The Dissertation Committee for Kurtus Steven Woolf Certifies that this is the approved version of the following dissertation: REGIONAL CHARACTER OF THE LOWER TUSCALOOSA FORMATION DEPOSITIONAL SYSTEMS AND TRENDS IN RESERVOIR QUALITY Committee: Lesli J. Wood, Supervisor William Fisher Ronald Steel Kitty Milliken Kyle Spikes REGIONAL CHARACTER OF THE LOWER TUSCALOOSA FORMATION DEPOSITIONAL SYSTEMS AND TRENDS IN RESERVOIR QUALITY by Kurtus Steven Woolf, B.S., M.S. Dissertation Presented to the Faculty of the Graduate School of The University of Texas at Austin in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy The University of Texas at Austin December 2012 Dedication To Julie, Trevor, and Lily Acknowledgments I would like to thank Dr. Lesli Wood for providing guidance and support throughout my time at the University of Texas. I appreciate the additional advice and support given by the other members of my committee: Dr. William Fisher, Dr. Ronald Steel, Dr. Kitty Milliken, and Dr. Kyle Spikes. I would like to thank Dr. Peter Flaig for assistance in taking core photographs and for reviewing portions of this dissertation. I appreciate the collaboration and data provided by Dr. Susan Hovorka, Ramon Trevino, and David Carr from the Gulf Coast Carbon Center at the Bureau of Economic Geology. This dissertation was made possible by the financial support of The Jackson School of Geosciences, and the Bureau of Economic Geology. I appreciate the support of the members of the Quantitative Clastics Laboratory Industrial Associates consortium including Anadarko, BHP Billiton, Cairn, ExxonMobil, Marathon, Saudi Aramco, Statoil, and Woodside. Additional funding was provided by the SIPES Foundation, AAPG Grants in Aid, Devon Energy, and Hess Corporation. Finally, I would like to thank my wife Julie and two children, Trevor and Lily, for their patience, support, motivation, and love during all the long hours and years “daddy was at school”. v Regional Character of the Lower Tuscaloosa Formation Depositional Systems and Trends in Reservoir Quality Kurtus Steven Woolf, PhD The University of Texas at Austin, 2012 Supervisor: Lesli J. Wood For decades the Upper Cretaceous Lower Tuscaloosa Formation of the U.S. Gulf Coast has been considered an onshore hydrocarbon play with no equivalent offshore deposits. A better understanding of the Lower Tuscaloosa sequence stratigraphic and paleogeographic framework, source-to-sink depositional environments, magnitude of fluvial systems, regional trends in reservoir quality, and structural influences on its deposition along with newly acquired data from offshore wells has changed this decades- long paradigm of the Lower Tuscaloosa as simply an onshore play. The mid-Cenomanian unconformity, underlying the Lower Tuscaloosa, formed an extensive regional network of incised valleys. This incision and accompanying low accommodation allowed for sediment bypass and deposition of over 330 m thick gravity- driven sand-rich deposits over 400 km from their equivalent shelf edge. Subsequently a transgressive systems tract comprised of four fluvial sequences in the Lower Tuscaloosa Massive sand and an overlying estuarine sequence (Stringer sand) filled the incised valleys. Both wave- and tide-dominated deltaic facies of the Lower Tuscaloosa are located at the mouths of incised valleys proximal to the shelf edge. Deltaic and estuarine depositional environments were interpreted from impoverished trace fossil suites of the vi Cruziana Ichnofacies and detailed sedimentological observations. The location and trend of valleys are controlled by basement structures. Lower Tuscaloosa rivers were 3.8m – 7.8m deep and 145m – 721m wide comparable to the Siwalik Group outcrop and the modern Missouri River. These systems were capable of transporting large amounts of sediment indicating the Lower Tuscaloosa was capable of transporting large amounts of sediments to the shelf edge for resedimentation into the deep offshore. Anomalously high porosity (>25%) and permeability (>1200md) in the Lower Tuscaloosa at stratigraphic depths below 20,000 ft. are influenced by chlorite coating the detrital grains. Chlorite coatings block quartz nucleation sites inhibiting quartz cementation. Chlorite coats in the Lower Tuscaloosa are controlled by the presence and abundance of volcanic rock fragments supplying the ions needed for the formation of chlorite. Chlorite decrease to the east in sediments derived from the Appalachian Mountains. An increase in chlorite in westward samples correlates with an increase of volcanic rock fragments derived from the Ouachita Mountains. vii Table of Contents List of Tables ....................................................................................................... xiii List of Figures ...................................................................................................... xiv Chapter 1: Introduction, Regional Setting, Summary of Data and Methods, and Objectives .......................................................................................................1 Introduction .....................................................................................................1 Regional Setting ..............................................................................................3 Lithostratigraphy/Paleogeography .........................................................6 Sequence Stratigraphy ...........................................................................9 Structure ...............................................................................................11 Summary of Data and Methods ....................................................................13 Summary of chapters ....................................................................................15 References .....................................................................................................19 Chapter 2: Sequence Stratigraphic and Paleogeographic Framework: Influences on Sediment Distribution and Depositional Environments ...............................25 Introduction ...................................................................................................25 Data and Methods .........................................................................................27 Observations .................................................................................................28 Sequence framework, accumulation trends, and log character ............28 Discussion .....................................................................................................39 Isopach Trends and Paleogeography ...................................................39 S0 Sequence ................................................................................42 S1 Sequence ................................................................................43 S2 Sequence ................................................................................44 S3 Sequence ................................................................................44 Stringer Sequence .......................................................................45 Lower Tuscaloosa Formation Summary .....................................45 Depositional History ............................................................................46 Structural influences on sediment distributions ...................................48 viii Paleogeography ....................................................................................48 Deepwater Facies of the Lower Tuscaloosa ........................................49 Provenance ...........................................................................................50 Conclusions ...................................................................................................51 References .....................................................................................................53 Chapter 3: Facies Analysis and Depositional Systems of the Lower Tuscaloosa Formation ......................................................................................................56 Introduction ...................................................................................................56 Previous Work - Depositional Environments ...............................................57 Methods.........................................................................................................61 Facies Analysis .............................................................................................63 Fluvial Channels and Floodplains ........................................................64 Facies ..........................................................................................64 Facies Associations .....................................................................71 Estuaries ...............................................................................................73 Facies ..........................................................................................73 Facies Associations .....................................................................80 Deltas ...................................................................................................83 Facies ..........................................................................................86 Facies Associations .....................................................................88 Gravity-Driven Deepwater Deposits....................................................95