Sedimentary Rocks and Depositional Environments
Sedimentary rocks and their depositional environments are fundamental to all aspects of petroleum geoscience, including evaluation of the petroleum system, exploration, field appraisal, reservoir characterisation and development, and solving production issues. Equally, they are fundamental to the study of stratigraphy, mineral resources, water resources and global environmental change.
Sediments deposited in rivers and deserts, deltas and deep-sea fans, coasts, shelves and contourite drifts, bioherms and carbonate platforms, all differ significantly in their rock properties, diagenetic character, heterogeneity and architecture. Such differences are key to understanding their behaviour as source rocks, migration pathways, reservoir rocks and seals, in both conventional and unconventional hydrocarbon systems.
This course is designed to give the participant a succinct, state-of- the-art, overview of sediments, sedimentary rocks and their principal characteristics, thereby providing a broad understanding of the range of sedimentary environments and the rocks they comprise. It covers clastic, carbonate, evaporite and volcaniclastic sediments, and the full range of settings in which they are deposited – including continental, shallow marine and deepwater depositional environments. Careful consideration is given to the principal diagnostic features of sediments from the main environments – in the field, in cores/boreholes, and in modern systems. Rock features include sedimentary structures, ichnofacies, textures, composition, petrophysical characteristics, and biogenic/organic content. For each environment, selected wireline logs will be examined, and the overall rock geometry or architectural elements discussed. A series of case studies will illustrate a range of hydrocarbon fields and plays from each of the main depositional environments.
The presentations are fully illustrated with high quality colour images of sediments and sedimentary rocks from a wide range of modern, ancient and subsurface examples. Where possible the course can be run in conjunction with examination of cores in the lab, and/or with field work, in order to better illustrate key features.
The course will build on the handbook Sedimentary Rocks in the Field (Stow, 2005) and the new edition in preparation, Sedimentary Rocks in the Field and Core (Stow and Gerard, 2021). Each participant will receive a copy of the latest revised edition of this book as well as a full set of the PowerPoint presentations.
Upon completion of the course, participants will be able to:
- UNDERSTAND the economic and environmental significance of sedimentary rocks
- APPRECIATE the full range of sedimentary rocks and their key differences
- RECOGNISE the nature and origin of the principal sediment characteristics
- DISTINGUISH between types of sedimentary rocks – modern, ancient and subsurface
- EVALUATE sediments in terms of the processes and environments of deposition
- ASSESS and interpret facies associations, sequences and architectural elements
- FOCUS on source, reservoir and seal properties of different sediment types
- RESOLVE clearly and simply between different depositional environments in the subsurface
- GAIN an astute understanding of what questions to ask and what analyses to make
- BECOME a better 21st century sedimentologist
Unit 1: Introduction and Overview.
- Course aims and content
- Classification and properties of sedimentary rocks
- Interpretation of depositional environments
- Methods of study: field, core and laboratory
- Significance: resources, water and the environmental record
Unit 2: Principal characteristics of sedimentary rocks.
- Introduction and facies concept
- Bedding and lamination
- Primary structures: erosional and depositional
- Secondary structures: post-depositional deformation & dewatering
- Biogenic structures: trace fossils, bioturbation, ichnofabrics and ichnofacies
- Chemogenic sedimentary structures
- Sediment texture and fabric: grain size, sorting, grain fabric
- Sediment composition and colour
- Principal diagenetic changes: physical and chemical
Unit 3: Siliciclastic sedimentary rocks
- Conglomerates: definition, types, characteristics, classification, occurrence
- Sandstones: definition, types, characteristics, classification, occurrence
- Mudrocks: definition, types, characteristics, classification, occurrence
- Hydrocarbon significance: source, reservoir and seal
Unit 4: Biogenic sedimentary rocks
- Carbonate rocks: definition, types, characteristics, classification, occurrence
- Cherts and siliceous sediments: definition, types, characteristics, classification, occurrence
- Phosphorites: definition, types, characteristics, classification, occurrence
- Coal: definition, types, characteristics, classification, occurrence
- Hydrocarbon significance: source, reservoir and seal
Unit 5: Chemogenic sedimentary rocks
- Evaporites: definition, types, characteristics, classification, occurrence
- Ironstones: definition, types, characteristics, classification, occurrence
- Soils, paleosols and duricrusts: definition, types, characteristics, classification, occurrence
Unit 6: Volcaniclastic sedimentary rocks
- Definition, range of types and classification
- Principal sedimentary characteristics and occurrence
- Hydrocarbon significance: source, reservoir, seal and correlation
Unit 7: Interpretations and depositional environments
- Building blocks: facies characteristics and models
- Vertical sequences and cycles, wireline log characteristics
- Lateral trends and geometry
- Architectural elements and facies associations
- Sequence stratigraphy and bounding surfaces
- Controls, rates and preservation
Unit 8: Depositional environments summary
- Principal characteristics of each of the main depositional environments
- Hydrocarbon case studies from each of the main depositional environments
Case studies and exercises throughout course. Optional special topics – to be discussed in advance. Potential for core session in core lab and/or for complementary field work.
The course is designed for all geologists, geophysicists and petroleum engineers involved in exploration and development. Project managers and senior management would also benefit from such a course as a refresher.
- Boggs S., 2009 (Second edition). Petrology of Sedimentary Rocks, Prentice Hall.
- Leeder M.R., 2011 (Second edition). Sedimentology and Sedimentary Basins: From Turbulence to Tectonics, Blackwell Science.
- Maynard J.B., Potter P.E., Depetris P.J., 2005. Mud and Mudstones: Introduction and Overview, Springer.
- Reading H.G., editor, 1996 (3rd edition) Sedimentary Environments and Facies, Blackwell.
- Selley R.C., 2000. Applied Sedimentology, Academic Press, San Diego.
- Stow D.A.V., 2005. Sedimentary Rocks in the Field, CRC Taylor & Francis Group.
About the Instructor
Professor Dorrik Stow FRSE is a leading specialist and internationally renowned expert in sedimentary systems, with over 40 years experience in modern, ancient and subsurface sediments. He has a particular interest in deepwater hydrocarbons, including numerous joint research projects with industry, individual consultancies, short course and field course organisation. His extensive record of scientific publications includes over 300 scientific papers and reports, numerous books and edited volumes. He has also worked closely on continental, shallow water, deltaic and carbonate systems from across the world.
Professor Stow is a lively, interesting and highly informed instructor. He is a seasoned presenter to audiences large and small, specialist and generalist. He is able to draw upon a great wealth of experience and examples to fully illustrate his presentations, and utilizes short course exercises for further instruction. His teaching and instruction has been highly acclaimed at all levels. He has worked with many different oil and gas companies in the provision of in-house or collective courses, field and core workshops, and in collaborative research projects.
His recent text Sedimentary Rocks in the Field (Manson, 2005) is a must-have for students and professional geologists alike, while Oceans: An Illustrated Reference (Oxford University Press and University of Chicago Press, 2004) and, more recently, Vanished Ocean (Oxford University Press, 2010) are written as popular science. He has worked both in industry and university and is currently Emeritus Professor (Petroleum Geoscience) at Heriot Watt University (Edinburgh, UK), Distinguished Professor at the China University of Geoscience (Wuhan, China), and Leverhulme Emeritus fellow. Professor Stow has been an enthusiastic lecturer and speaker throughout the world, on everything from deep-sea turbidites to the Lost Tethys Ocean.