Low-Energy Processes for Unconventional Oil Recovery fills a gap in the oil and gas literature. Today in our globalized society, the oil industry has to demonstrate how oil recovery can be done responsibly over the life-cycle of the project, clearly articulating the energy efficiency as well as carbon dioxide (CO₂) and environmental footprints of the chosen recovery processes. There is no silver bullet solution, and Industry, Academia, and Governments must collaborate to pursue avenues to reduce greenhouse gas (GHG) emissions by improving energy efficiency from “well” to “wheels.” The produced CO₂ can also be sequestered, but the evaluation of carbon capture and storage requires careful analysis of the additional CO₂ budgets and total energy balances.

World unconventional and heavy-oil production amounts to some 10 million B/D or almost 10% of global oil supply. Two million B/D of this is produced by means of steam injection processes using either cyclic steam stimulation, steamdrive or steamflood, or steam-assisted gravity drainage (SAGD). Many projects are on the drawing board, but need improved energy efficiency and lower CO₂ footprint to enable project sanction.

The subject has been under much research and development over the last decade and is still undergoing many developments. As such, this monograph by Reza Fassihi and Anthony (Tony) Kovscek presents a state-of-the-art analysis. Both authors have published extensively on a broad range of enhanced-oil-recovery (EOR) subjects and are recognized as experts in the subjects covered.

Dr. Fassihi is a distinguished advisor with BHP Petroleum in Houston and is responsible for subsurface technical assurance on global projects. Before this, he was the unconventional technology manager with BP. He has more than 35 years of experience in petroleum research, development and reservoir management, including waterflood and EOR projects. He has authored/co-authored more than 40 peer-reviewed papers on a broad range of petroleum engineering and research topics. He holds a PhD degree in petroleum engineering from Stanford University.

Dr. Kovscek is a professor at Stanford University since 1996 and is the Keleen and Carlton Beal Professor as well as the current chair of the Energy Resources Department. His PhD research was in chemical engineering at the University of California at Berkeley. He has authored more than 125 peer-reviewed publications, mainly focusing on enhanced-recovery processes for unconventional resources.

The authors bring together their complementing expertise to provide the reader with an in-depth discussion of a range of alternative recovery techniques. Most recovery methods are focused on heavy-oil recovery, but some have applications in light oil reservoirs as well. With the recent industry drive and focus to recover hydrocarbons from tight rock and shale resources, a chapter has also been devoted to shale oil recovery to be fully aligned with the scope of this book.

The following is a brief outline of the topics covered:

• Chapter 1 discusses the challenges of heavy-oil production. Worldwide occurrence of unconventional resources is presented by category and the importance of oil mobility is explained. A range of recovery technologies is introduced, and examples are provided of energy efficiency and CO₂ emissions.

• Chapter 2 describes technical aspects of the oil extraction methods that can be applied in unconventional oil recovery. Amongst others, it includes primary recovery, steam-based processes, polymer flooding, solvent injection, and air injection. Screening tools are provided.

• Chapter 3 is devoted to fluid and rock properties, including thermal properties and wettability. The role of oil-phase constituents and the complexity of reservoir fluid characterization are explained in detail. Several useful correlations are provided.

• Chapter 4 provides primary heavy-oil recovery tools with cold heavy-oil production. It includes a discussion on cold heavy-oil production with sand (CHOPS) and describes the importance of foamy oil behavior. Several CHOPS case studies are presented.

• Waterflooding and its derivatives, such as polymer flooding, are the subject of Chapter 5. The importance of these techniques is growing with polymer flooding being applied within ever greater oil viscosity reservoirs with tuned injection schedules. The viscosity reducing potential of emulsions in aqueous flooding techniques is also described. The chapter is concluded with a discussion on CO₂ water-alternating-gas (WAG).

• Chapter 6 builds on Prats’ monograph on thermal recovery and Butler’s work on SAGD with a thorough treatment of steam injection and enhancements with steam additives. Energy efficiency and CO₂ emissions are calculated, and the improvement potential of solvent addition to steam in terms of recovery and energy efficiency is described. Recent field cases with solvent or diluent addition to steam are provided.

• Chapter 7 provides the reader with an in-depth and state-of-the-art description of air-injection techniques. It includes heavy-oil in-situ combustion and high-pressure air injection; the latter is focused on lighter oils in tight reservoirs. Oxidation kinetics and the different oxidation and cracking regimes are discussed in detail, together with laboratory techniques and field examples. The importance of selection of the right reservoirs for air injection is emphasized, with screening and forecasting tools provided. The modeling challenge is also discussed and calculation of energy efficiency and GHG emission is included. Associated field experience is described with several relevant cases, and important safety and operational aspects are clarified in detail.

• Alternative sources to heat the reservoir are introduced in Chapter 8. External heat sources, such as nuclear energy or solar heating, as well as in-situ techniques with electromagnetic heating and in-situ upgrading are presented. Energy efficiencies are compared and improvement options provided.

• In Chapter 9, important reservoir simulation challenges are covered. In a thorough discussion, complex aspects of reservoir simulation are explained in an easy to understand manner, and the intricacies in application to the complex recovery techniques that are discussed in this book are elaborated upon.

• Chapter 10 informs the reader about process facilities and operation as well as integration aspects. Important surface-facility technologies are presented with their operational parameters. The impact of the choice of the process on the energy balance and emissions is of course also covered.

• Chapter 11 describes the unconventional shale resources in terms of reservoir characterization, production mechanisms, and methods of enhancing liquid-rich shale oil recovery. Many methods discussed here are at a research phase and, hence, their field applicability is still uncertain. But, operators are working toward maturing these technologies.

I consider this publication as a significant contribution to the petroleum industry and recommend its use as a professional reference to help guide EOR project design and as a training tool for petroleum engineering schools.

Assen, The Netherlands

Johan van Dorp,

Shell Group principal technical expert for thermal EOR (2008–2016)