STRATIGRAPHIC ARCHITECTURE AND FACIES ANALYSIS OF THE LOWER CRETACEOUS DINA MEMBER OF THE MANNVILLE GROUP IN NORTHWEST SASKATCHEWAN A Thesis Submitted to the Faculty of Graduate Studies and Research In Partial Fulfillment of the Requirements For the Degree of Master of Science In Geology University of Regina By Daniel Jonathon Kohlruss Regina, Saskatchewan October, 2012 Copyright 2012, D.J. Kohlruss UNIVERSITY OF REGINA FACULTY OF GRADUATE STUDIES AND RESEARCH SUPERVISORY AND EXAMINING COMMITTEE Daniel Jonathon Kohlruss, candidate for the degree of Master of Science in Geology, has presented a thesis titled, Stratigraphic Architecture and Facies Analysis of the Lower Cretaceous Dina Member of the Mannville Group in Northwest Saskatchewan, in an oral examination held on October 5, 2012. The following committee members have found the thesis acceptable in form and content, and that the candidate demonstrated satisfactory knowledge of the subject material. External Examiner: Dr. Steven Hubbard, University of Calgary Co-Supervisor: Dr. Guoxiang Chi, Department of Geology Co-Supervisor: Dr. Per Kent Pederson, Adjunct Committee Member: Dr. Maria Velez Caicedo, Department of Geology Chair of Defense: Dr. Renata Raina, Department of Chemistry & Biochemistry *Not present at defense ABSTRACT Recent exploration activity in northwest Saskatchewan, north of the Clearwater River Valley along the Alberta provincial border, has revealed an extensive bitumen resource. 1.4 billion barrels to 2.3 billion barrels (222 million m3 to 371 million m3) of bitumen is estimated in place. The bitumen-bearing sandstones belong to the Dina Member of the Lower Cretaceous Mannville Group, stratigraphically equivalent to Alberta’s McMurray Formation. The purpose of this study is to determine the stratigraphic architecture of the Dina Member and its control on bitumen distribution in the study area. The Dina Member in northwest Saskatchewan was deposited unconformably on top of the underlying Devonian Elk Point Group with the thickest Dina sandstones residing within paleo-topographic lows on the unconformity surface. The Dina Member was extensively eroded by Pleistocene glacial processes and is unconformably overlain by Pleistocene glacial tills. Analysis of 83 stratigraphic test hole drill cores and 255 geophysical well log suites has revealed 8 recurring facies and 5 facies associations. The facies are comprised of siliciclastic sediments, including sandstones, siltstones, mudstones and in rare instances, coal. These facies are predominantly non-marine in origin, including fluvial sediments and associated over-bank deposits. Many fluvial facies exhibit a significant tidal and/or seasonal brackish water influence. Tidal indicators are manifested as rhythmic grain size striping, reactivation surfaces and co- and back-flow structures. Brackish conditions are indicated by impoverished, mono-specific assemblages of diminutive trace fossils in mud beds and discrete sand layers, along with marine palynmorphs and microfossils. I Deposition of the Dina Member is interpreted to have occurred within an incised valley system formed as a result of a relative base-level drop, which initiated trenching and deepening of pre-existing valleys. Braided channel deposits proceeded to fill the lowest portions of the valley during the lowstand and part of the subsequent transgression. As the valley was gradually filled and the lateral accommodation space increased, fluvial style changed from braided to meandering, with deposition of laterally accreted point-bar deposits. These manifest as inclined stratification (IS) and inclined heterolithic stratification (IHS) overlying basal trough cross-bed sets. Mud filled, oxbow lake deposits were also observed in close association with the point-bar deposits. Bitumen distribution throughout the study area is not uniform and has several controls. Bitumen saturation is highest where braided fluvial and IS deposits are found, especially when stacked. Conversely, IHS deposits and mud filled oxbow lake deposits restrict oil flow and in cases act as flow barriers to oil migration. Bitumen is trapped laterally by the incised valley walls created by the sub-Cretaceous unconformity, where bitumen saturated sand pinches out against the impermeable carbonates. The Dina sandstones, in turn, were sealed above by shales of the Clearwater Formation/ Cummings Member of the Mannville Group. II ACKNOWLEDGEMENTS Funding for a large portion of this project was provided by the Saskatchewan Ministry of Energy and Resources, most notably was a grant to Dr. Guoxiang Chi and Dr. Per Kent Pedersen at the University of Regina. Many individuals have contributed to this thesis in many different ways, through technical support, inspiration and motivation. I would like to thank Dr. Guoxiang Chi and Dr. Per Kent Pedersen for their technical support, patience and the freedom to think, work and act independently throughout the process. Their many hours of editing and valuable feedback are greatly appreciated. I’d like to thank all my colleagues at the Ministry of Energy and Resources, specifically, Arden Marsh, for his technical expertise with data management and mapping software, as well for our many discussions surrounding sedimentology and stratigraphy. I’d also like to thank Melinda Yurkowski who always believed I would finish this project and provided the time needed to accomplish my goal. I’d also like to thank Jeff Coolican, who “took-up-the-slack” in our shared work duties, while I focused on research. I’d like to thank Gavin Jensen and Arden Marsh for their assistance preparing for our Clearwater field season as well their time and energy while in the field. I’d also like to thank Megan Love and Tyler Music, who provided technical support while assembling my thesis. III DEDICATION I would like to dedicate this thesis to my two children. Without them I would not have the patience, maturity or strength to accomplish a goal of this magnitude. They teach me more than I will ever be able to teach them and they make me a better person. My son Ethan is the strongest individual I know and whenever I feel I can not accomplish a goal, I look to him for motivation. He truly is my hero and I am blessed to be his dad. My daughter Avery inspires me every day with her beautiful personality, endless curiosity and love of rocks and dogs. She makes me feel privileged to have the career I’ve chosen and appreciate every day I am a geologist. I look forward to working with her someday. Finally, I owe a very special thanks and dedication to my wife Melanie, who provided endless love, patience, encouragement and inspiration. She is always there when I need her most and without her I would not have attempted, let alone finished this thesis. “If you want to take the island, burn the boats!” –Tony Robbins IV TABLE OF CONTENTS ABSTRACT……………………………………………………………………………… I ACKNOWLEDGEMENTS...…………………………………………………………... III DEDICATION.……………………………………………………………...………….. IV TABLE OF CONTENTS…………………………………………………………………V LIST OF TABLES……………………………………………………………………..VIII LIST OF FIGURES……………………………………………………………………...IX 1. INTRODUCTION ......................................................................................................... 1 1.1 Purpose and Objectives ........................................................................................ 3 1.2 Previous Work ...................................................................................................... 5 1.3 A Review of Estuary Depositional Models .......................................................... 8 1.3.1 Introduction ................................................................................................... 8 1.3.2 Physical Processes ........................................................................................ 9 1.3.2.1 River and Tidal Currents ......................................................................... 11 1.3.3 Chemical Processes and Water Circulation ................................................ 13 1.3.4 Biological Processes ................................................................................... 15 1.3.5 Morphology................................................................................................. 16 1.3.6 Cross-Bedding and Tidal Indicators ........................................................... 18 1.3.7 Grain Size Distribution ............................................................................... 19 1.3.8 Estuarine Depositional Model..................................................................... 21 1.4 Study Area .......................................................................................................... 22 1.5 Study Methods.................................................................................................... 22 1.5.1 Net Pay and Net Water/Lean Mapping ....................................................... 25 1.5.2 Geological Isopach and Structure Maps ..................................................... 26 1.5.3 Geological Cross-Sections .......................................................................... 27 2. GEOLOGICAL SETTING .......................................................................................... 28 2.1 Regional Geology ............................................................................................... 28 2.2 McMurray Sub-Basin ......................................................................................... 36 3 FACIES DESCRIPTIONS AND DEPOSITIONAL INTERPRETATIONS ........... 41 3.1 Introduction ........................................................................................................ 41 3.2 Facies Descriptions and Interpretations ............................................................. 41 3.2.1 Facies 1: Massive Sandstone ...................................................................... 41 V 3.2.2 Facies 2: Ripple Cross laminated Sandstone .............................................. 46 3.2.3 Facies 3: Planar Cross-bedded Sandstone ................................................... 48 3.2.4 Facies 4: Trough Cross-Bedded Sandstone ................................................ 54 3.2.4.1 Facies 4a: Medium to Very Coarse Trough Cross-Bedded Sandstone ... 54 3.2.4.2 Facies 4b: Massive to Trough Cross-Bedded Pebbly Sandstone ............ 59 3.2.5 Facies 5: Pebble Conglomerate ................................................................... 62 3.2.6 Facies 6: Inter-bedded Sandstone and Bioturbated Mudstone .................... 65 3.2.7 Facies 7: Siltstone, Mudstone, and Coal ..................................................... 73 3.2.8 Facies 8: Laminated Siltstone to Very Fine Sandstone .............................. 77 3.3 Facies Associations ............................................................................................ 80 3.3.1 Facies Association 1: Braided Fluvial Channel .......................................... 80 3.3.2 Facies Association 2: Tidally Influenced Meander Channel Deposits ...... 88 3.3.3 Facies Association 3: Oxbow Lake Fill ...................................................... 99 3.3.4 Facies Association 4: Flood Plain Crevasse Splay ................................... 102 3.3.5 Facies Association 5: Floodplain Deposits ............................................... 105 4. STRATIGRAPHIC ARCHITECTURE AND DEPOSITIONAL MODEL .............. 109 4.1 Introduction ...................................................................................................... 109 4.2 Structural and Isopach Maps ............................................................................ 109 4.3 Facies Association Structural Cross-Sections .................................................. 115 4.3.1 Cross-section A-A’ ................................................................................... 116 4.3.2 Cross-section B-B’ .................................................................................... 119 4.3.3 Cross-section C-C’ .................................................................................... 121 4.3.4 Cross-section D-D’ ................................................................................... 123 4.3.5 Cross-section E-E’ .................................................................................... 126 4.3.6 Cross-section F-F’ ..................................................................................... 128 4.4 Depositional Model .......................................................................................... 131 5. BITUMEN DISTRIBUTION ................................................................................. 137 5.1 Introduction ...................................................................................................... 137 5.2 Bitumen Distribution ........................................................................................ 137 5.3 Trapping and Bitumen Distribution Controls................................................... 149 6. CONCLUSIONS..................................................................................................... 156 LIST OF REFERENCES.………………………………………………………………158 VI APPENDIX I : Formation and Facies Association Tops..………………………….….168 APPENDIX II : Bitumen Saturation Calculations….………………………………….177 APPENDIX III : Palynological Report..………………………………………..………185 VII LIST OF TABLES Table 3.1 Summary of facies within study area....………………………………………43 Table 3.2 Description interpretation and sequence stratigraphic nomenclature of facies associations in the study area………………….…………………………………………81 VIII