Unconventional reservoirs have provided a great opportunity to the industry for assuring the continual production of hydrocarbons, particularly in North America. Despite the uptake of output in deep-water assets, the overall declining production trend in land operations from conventional reservoirs required a step-change in production output. Innovations over two decades in drilling and completion paved the way for commercial-scale field development in unconventional settings, starting in the Barnett play in Texas. Long-term performance prediction became a challenge given the steep initial rate decline trend in any individual well. Over time, evolving studies provided solutions to this obstacle, leading to more realistic performance predictions and reserve estimation. This E-book attempts to address two significant points of interest while tackling an unconventional play. Chapter 1 defines reserve and resource and their estimation process in this context. Then, Chapter 2 reviews items related to regulatory guidelines about resource and reserve definitions and categorizations. Besides reserve reporting and standards, the detailed discussion entails operators, regulators, and lending institutions. Items such as tax royalty and PSC contracts, production sharing contracts, risk service agreements also became part of this chapter’s content to provide a holistic picture. Chapter 3 delves into decline-curve analysis or DCA, a bedrock of reserve estimation process for an asset of any origin. Both empirical and analytical methods are discussed which have evolved well over a decade, followed by probabilistic DCA and rate-transient analysis. In this context, discussions appear on frac hits, enhanced recovery with cyclic CO2 injection, and anomalous diffusion in realistic settings. Overall, these and related items attempt to provide a holistic overview of available technology that is in play in the domain of unconventional reservoirs. This book fills an important gap in published information about unconventional reservoirs, synthesizing information scattered through many papers and other documents in the technical literature in one brief and readily accessible document. The authors, Cenk Temizel, Cengiz Yegin, and Shah Kabir, have considerable experience working with this energy source that has revolutionized the world’s energy supply. They ably draw on this experience they explore the key issues that resource evaluators and users must consider.
