Sedimentology, Diagenetic History and Reservoir Characterization of the Coronach Member, Herald Formation, Wiiliston Basin, SE Saskatchewan A Thesis Submitted to the Faculty of Graduate Studies and Research In Partial Fullfillment of the Requirements for the Degree of Master of Science in Geology University of Regina by Mark Anthony Urban Regina, Saskatchewan July 22,2010 The author claims right copyright. Use shall not be made of the material contained herein without the proper acknowledgment. Library and Archives Bibliotheque et Canada Archives Canada Published Heritage Direction du Branch Patrimoine de I'edition 395 Wellington Street 395, rue Wellington Ottawa ON K1A0N4 Ottawa ON K1A 0N4 Canada Canada Your file Votre reference ISBN: 978-0-494-88474-4 Our file Notre reference ISBN: 978-0-494-88474-4 NOTICE: AVIS: The author has granted a non­ L'auteur a accorde une licence non exclusive exclusive license allowing Library and permettant a la Bibliotheque et Archives Archives Canada to reproduce, Canada de reproduire, publier, archiver, publish, archive, preserve, conserve, sauvegarder, conserver, transmettre au public communicate to the public by par telecommunication ou par I'lnternet, preter, telecommunication or on the Internet, distribuer et vendre des theses partout dans le loan, distrbute and sell theses monde, a des fins commerciales ou autres, sur worldwide, for commercial or non­ support microforme, papier, electronique et/ou commercial purposes, in microform, autres formats. paper, electronic and/or any other formats. The author retains copyright L'auteur conserve la propriete du droit d'auteur ownership and moral rights in this et des droits moraux qui protege cette these. Ni thesis. Neither the thesis nor la these ni des extraits substantiels de celle-ci substantial extracts from it may be ne doivent etre imprimes ou autrement printed or otherwise reproduced reproduits sans son autorisation. without the author's permission. In compliance with the Canadian Conformement a la loi canadienne sur la Privacy Act some supporting forms protection de la vie privee, quelques may have been removed from this formulaires secondaires ont ete enleves de thesis. cette these. While these forms may be included Bien que ces formulaires aient inclus dans in the document page count, their la pagination, il n'y aura aucun contenu removal does not represent any loss manquant. of content from the thesis. Canada UNIVERSITY OF REGINA FACULTY OF GRADUATE STUDIES AND RESEARCH SUPERVISORY AND EXAMINING COMMITTEE Mark Anthony Urban, candidate for the degree of Master of Science in Geology, has presented a thesis titled, Sedimentoiogy, Diagenetic History and Reservoir Characterization of the Coronach Member, Herald Formation, Wiliiston Basin, SE Saskatchewan, in an oral examination held on May 5, 2010. 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. Malcolm Wilson, Office of Energy and Environment Supervisor: Dr. Hairuo Qing, Department of Geology Committee Member: Dr. Guoxiang Chi, Department of Geology Committee Member: Dr. Donald Kent, Adjunct Professor, Department of Geology Chair of Defense: Dr. Daoyong (Tony) Yang, Faculty of Engineering and Applied Science Abstract The Coronach Member of the Herald Formation (late Maysvillian to early Richmondian) in southeastern Saskatchewan was deposited on a gently-sloping, shallow- water ramp, which was part of a larger, vast epicontinental sea that covered most of Laurentia in the Late Ordovician. Sabkha-type evaporites and intertidal stromatolitic boundstones characterize the upper ramp facies, whilst the lower ramp consists of subtidal skeletal wackestones to red algal-green algal-stromatoporid reef mounds or biostromes. The succession portrays a shallowing-up and brining-up carbonate-evaporite cycle similar to the modern Abu Dhabi Sabkha of the Persian Gulf. The Coronach Member can be divided into five facies based on the depositional and diagenetic settings. In upwards succession they are: 1) an anoxic subtidal setting, 2) an oxygenated, shallow-water subtidal setting, 3) a penesaline intertidal setting, 4) a hypersaline supratidal (sabkha) setting, and 5) an exposed diagenetic caliche horizon. Initial deposition of the Coronach Member began with a deepening event that resulted in deposition of basal, organic-rich rocks that are very similar to kukersites from the Yeoman Formation (Edenian to Maysvillian). These shallow-water, photosynthesizing alginites are succeeded by shallow to very shallow-water, dominantly algal-reef mounds and skeletal rudstones/grainstones. Reef mounds display a consistent vertical ecological zonation similar to modern reef systems. Rising salinity, due to increasing restriction or reduced energy, is indicated by a drop in skeletal diversity and abundance with deposition of Planolites-bunowed mudstones. These were deposited in a lagoonal environment. A tidal flat system containing tidal channels, beach ridges, levees, and variable forms of stromatolites prograded overtop of subtidal sediments. i Stromatolites are composed of cyanobacteria, which trapped mainly storm-deposited peloidal sediment by the process of agglutination. Stromatolitic forms include a wide range from domal to smooth and flat. Salinity continued to rise with deposition of gypsum and anhydrite in a sabkha-type setting. Nodular anhydrite was emplaced in the capillary zone by highly-evaporated marine waters and refluxing brines. Locally, saline ponds led to rare bedded anhydrite. Reflux brines also led to complete dolomitization of the intertidal and supratidal sediments. As regression continued, either due to sediment infill of the basin or falling sea-level, supratidal rocks were subjected to prolonged exposure. Diagenetic alteration of these sediments led to formation of a caliche horizon. Early dolomitization of intertidal stromatolites has led to a zone with the highest porosity. Reservoirs in this facies make for prolific producers on the United States side of the Williston Basin. Production on the Saskatchewan side however, has not been recorded in the Coronach Member, which is a function of 1) lower porosity and permeability, 2) slightly thinner reservoirs, 3) increased distance from thermally-mature source rocks, 4) hydrodynamic flushing of stratigraphic traps, 5) a shorter deep- exploration period, and 6) smaller structural traps. The Coronach Member does have potentially large reserves in Saskatchewan, as observed from consistent oil-staining and porous rock in core. Exploration should focus on existing structural traps where Red River reservoirs are already producing, or other structures related to basement highs that can be found using two- and three-dimensional seismic. Existing Coronach reservoirs in north-eastern Montana occur mere kilometres from the Saskatchewan border, emphasizing the possible presence of hydrocarbon accumulations in the northern half of the Williston Basin. ii Acknowledgments I would like to thank Dr. Hairuo Qing for his supervision and direction of this thesis, the workers at the Geological Subsurface Laboratory in Regina and at the North Dakota Geological Survey lab in Grand Forks, and Talisman Energy for facilities and information support, especially the library staff. An NSERC Discovery Grant (155012) and the Ministry of Energy and Resources, under the Geoscience Research and Student Training Program, provided financial support for the research. The author is greatly indebted to John Lake (Lake Geological Services, Inc.), Dr. Jean-Yves Chatellier (Talisman Energy), Hugh Reid (Reid & Associates, Inc.) and Dr. Brian Pratt (University of Saskatchewan) for discussions on various topics. Also, the members of the 'Carbonate Liars Club' were a great resource for insights and suggestions. Lastly, I would like to thank my wife for her patience and support over the last few years. iii Table of Contents Page Abstract i Acknowledgements iii Table of Contents iv List of Figures vi List of Plates vii List of Tables viii List of Abbreviations ix 1.0 Introduction 1 2.0 Geological Setting 8 2.1 Structural Setting of the Williston Basin 8 2.2 Lower Paleozoic Stratigraphy 13 2.3 Palaeogeographical Setting 21 2.4 Red River Petroleum System 23 2.5 Williston Basin Hydrodynamics 24 3.0 Previous Work 28 4.0 Methods 31 5.0 Facies Descriptions and Interpretation 35 5.1 Lake Alma Anhydrite 38 5.1.1 Lake Alma Anhydrite Interpretation 41 5.2 Lake Alma Dolomudstones 44 5.2.1 Structures 44 5.2.2 Grains 49 5.2.3 Matrix 50 5.2.4 Diagenesis 51 5.2.5 Lake Alma Dolomudstone Summary and Interpretation 52 5.3 Facies 1 56 5.3.1 Structures 56 5.3.2 Grains 58 5.3.3 Matrix 58 5.3.4 Facies 1 Summary and Interpretation 58 5.4 Facies 2 62 5.4.1 Skeletal Grains 62 5.4.2 Non-skeletal Grains 79 5.4.3 Primary Structures 81 5.4.4 Matrix 83 5.4.5 Facies 2 Summary and Interpretation 84 5.5 Facies 2 Upper Contact 98 5.6 Facies 3 98 5.6.1 Primary Structures 101 5.6.2 Matrix and Grains 106 5.6.3 Facies 3 Summary and Interpretation 106 5.7 Facies 4 123 5.7.1 Primary Structures 123 5.7.2 Matrix 123 5.7.3 Facies 4 Summary and Interpretation 125 5.8 Facies 5 129 5.8.1 Matrix and Grains 130 5.8.2 Facies 5 Summary and Interpretation 130 5.9 Summary of Depositional Environment 136 5.9.1 Modern Depositional Analogues 148 iv 6.0 Diagenesis: Description, Geochemistry and Interpretation 155 6.1 Anhydrite 155 6.1.1 Anhydrite 1 Description and Interpretation 155 6.1.2 Anhydrite