We would like to thank several colleagues for their contributions to the development of this text. Tom Hewitt (now at Stanford University) introduced us to the usefulness of fractional-flow concepts in understanding immiscible-displacement processes while Paul Willhite was on sabbatical leave at Chevron Oil Field Research Corporation (now Chevron Production Technology Company). Fred Poettmann, one of our editors from the SPE Textbook Committee, provided problems from his EOR course at the Colorado School of Mines and also critical comments on each chapter. He passed away before he had an opportunity to use the text in his EOR class, a goal that he reminded us of through continual encouragement to finish the book. Fred Stalkup, the second editor for the text, provided valuable information for the chapter on miscible displacement. Several unknown external reviewers reviewed each chapter. We appreciate their comments, which contributed much to the text.

We are also indebted to many on the staffs at the University of Kansas and at the Society of Petroleum Engineers (SPE) in Dallas, who helped us in the completion of the text. At the University of Kansas, Ruth Sleeper and Shari Gladman prepared some of the text and Vera Sehon, Megan Gannon, and Jim Busse of the Center for Research Incorporated prepared graphics for several chapters and provided emergency repairs to other figures. The writing of this book spanned several years and several editors at SPE. We appreciate the editorial work of Flora Cohen, Carla Atwal, and Holly Hargadine. We also appreciate the review by our colleague, Shapour Vossoughi, and a number of students who took the course at the University of Kansas.

For the second edition, revisions made to Chapters 5 through 8 were reviewed by several colleagues at other institutions. These include Randy Seright (New Mexico Institute of Mining and Technology), Gary Pope (University of Texas at Austin), George Hirasaki (Rice University), and Sayed Farouq Ali (University of Calgary). Field case histories of application of miscible-flooding processes (Chapter 6) were provided by several individuals. These include Lanny Schoeling, Mark Linroth, Steve Pennell, and Reza Barati (Kinder Morgan Company) for assistance in data gathering and reviewing the material for the Scurry Area Canyon Reef Operations Committee (SACROC) Unit field case; Gary F. Teletzke (Exxon Mobil Upstream Research Company) for his review and guidance of the Means San Andres Unit field case; Charles A. Peterson and Bob Schwager (Devon Energy Company), who provided more-recent data and information resulting from field monitoring in discussion of the Madison reservoir CO₂ project, which is based almost exclusively on Peterson et al. (2012); and Nick Valenti and Travis Melster (Quantum Resources) for review of the write-up and for providing current field data for the Jay/Little Escambia Creek (LEC) Field N₂ Miscible-Flood Project.

Finally, we especially acknowledge the SPE staff responsible for managing and editing the book throughout the process leading to publication. Jane Eden, Editorial Service Manager, oversaw and guided the project. Her extensive interaction with the authors was very helpful. Judith Mathis, Senior Staff Editor, who was responsible for editing the manuscript, did a superb job in requiring consistency and accuracy in the text, and clear imaging of figures and tables. She and Jane were clearly dedicated to producing a book of high quality. Recognition is also given to David Grant, Digital Publishing Manager, for the excellent cover design.

G. Paul Willhite

Don W. Green

November 2017