Access to sustainable, affordable water, energy and food are some of the major technological challenges of the 21^st century. How do we manage precious and scarce water resources, while preventing pollution? How do we extract the most of our remaining supplies of conventional oil and gas? How can we extract, safely, shale gas and oil? Can we collect and store carbon dioxide in the subsurface to prevent atmospheric emissions and help avoid dangerous climate change? Can we manage to provide sufficient energy for a growing world’s population with an aspiration for improved prosperity? An understanding of these challenges involves multiphase flow in porous media – the flow of water, oil and gas with associated pollutants – underground in geological formations. 

The subject of multiphase flow in porous media is undergoing a revolution, not just as a result of its many important applications, but because of developments in our quantitative understanding of how fluids are arranged and move, combined with the ability to image fluids at the micron-scale inside rocks. 

This course will apply concepts of multiphase flow in porous media to understand and design recovery from oil and gas reservoirs. This is one of the major challenges referred to above – at present we recover only around one third of the oil from fields we have discovered. How can we improve this to the 50-60% now achievable with the best engineering methods, and beyond?

This course will describe how different methods can be used to:

• assess the development potential of oil and gas reservoirs;

• identify principal displacement mechanisms controlling performance;

• predict recovery and oil-in-place;

• understand reservoir simulation methods. It is assumed that you already know about hydrocarbon phase behaviour, reservoir simulation and the principal reservoir drive mechanisms. You will also need to know Darcy’s law and the meaning of relative permeability and fractional flow, although these are described again in these notes. The emphasis will be on learning fundamentals with some time taken to cover basic concepts. I will not repeat details that are well covered in other textbook, or which are not strictly relevant to this course. Furthermore, these notes will not illustrate the concepts with field examples: this is better left to project work or indeed industrial experience. This is not a manual for reservoir engineers, but a teaching tool to establish the fundamentals.

1. Introduction to the oil industry – its history and stages of production.

2. Societal context: population, global production and climate change.

3. Oil terminology and definitions, recovery factor and reservoir pressure regimes.

4. Material balance for oil and gas reservoirs, including analysis for natural water drives, solution gas drives, compaction drives and gas cap expansion.

5. Decline curve analysis, including harmonic and hyperbolic decline.

6. Darcy’s law and dispersive transport.

7. Capillary pressure and the configuration of multiple fluids in the pore space.

8. Multiphase flow and relative permeability.

9. Displacement mechanisms including the Buckley-Leverett and Welge analysis for analytic oil recovery calculations.

10. Analytic solutions for imbibition.

Coursework

Tutorial questions are included at the end of these notes, as well as past examination papers. These questions will be used to test your knowledge and understanding of the material presented in lectures. Some of the questions will be done in class, others are for homework and others are for revision. Answers to some of the questions, where appropriate, will be given during the class. I will set a previous year’s examination as a homework exercise on which I can provide feedback, as mentioned above.

Recommended books

1. Fundamentals of Reservoir Engineering, L. P. Dake, Elsevier, (1991), ISBN 0-444-41830-X.

   This is the best book for the whole class and describes material balance, phase behaviour and Buckley-Leverett analysis.

2. Petroleum Engineering Principles and Practice, J. S. Archer and C. G. Wall, Graham and Trotman, (1986), ISBN 0-86010-665-9.

   This book was co-authored by John Archer, a Professor of Reservoir Engineering at Imperial who later was Vice-Chancellor of Heriot-Watt University.

3. Applied Petroleum Engineering, B. C. Craft and M. F. Hawkins, Prentice Hall, (1991), ISBN 0-13-039884-5.

   Excellent on material balance, but has a very practical focus with little explanation of the methods used.

4. Waterflooding, G. P. Willhite, Society of Petroleum Engineers, (1986), ISBN 1-55563-005-7.

   Another good textbook, but does not cover all the material in this class.

5. The Reservoir Engineering Aspects of Waterflooding, F. F. Craig, Jr., Society of Petroleum Engineers, (1971), ISBN 0-89520-202-6.

6. Enhanced Oil Recovery, L. W. Lake, Prentice Hall, Englewood Cliffs, (1989) 500 pages.

   This is a truly excellent and detailed book – one of the very best in petroleum engineering. It does cover much of the material in these notes, but – for improved oil recovery – at a level of detail which is much greater than we have time for in this course.

7. Groundwater, R. A. Freeze and J. A. Cherry, Prentice Hall, Inc, Englewood Cliffs, (1979).

   This is a standard hydrology text, but does not cover multiphase flow, and does not have a focus on oil recovery.

8. Porous Media: Fluid Transport and Pore Structure, F. A. L. Dullien, Academic Press, San Diego, 2^nd Edition, (1992).

   This is a fabulous research reference book that covers much of the scientific material in these notes and contains a lot of experimentally-based physical insight into multiphase flow.

9. Dynamics of Fluids in Porous Media, J. Bear, Dover Publications, Inc, New York, (1972).

   A classic in its field – indeed it help establish the subject of flow in porous media as a discipline. Very mathematical, but contains a lot of useful information.

10. Capillary and Wetting Phenomena: Drops, Bubbles, Pearls, Waves, P-G de Gennes, F. Brochard-Wyart and D. Quéré, Springer (2002).

    The first author is the charismatic, and now sadly deceased, physics Nobel Prize winner, Pierre-Giles de Gennes. A fascinating book, packed full of interesting analysis, but not directly relevant to flow in porous media. Acquire a French accent, light up a Gaulois, wave your hands and voilá – brilliant insights into physics!

11. Multiphase flow in permeable media: a pore-scale perspective, M J Blunt, Cambrdige University Press (2017).

    This is my own recently-published book that covers the material on multiphase flow in these notes in more detail.
    

The course will be presented in lectures and examined both as a written exam (80%) and as an assessed exercise, which will be the 2016 exam (or another assignment described in class) – you will need to complete all five questions (20%). There will be no oral examination. In addition optional past examination papers can be attempted for revision.