Almost three decades have passed since the early exploration of the north Texas, Barnett shale. The Barnett serves as an example study for the shale life cycle. Operators in North America have used the Barnett-shale development as a roadmap for the exploration of new shale plays like the Marcellus, Haynesville, and Eagle Ford, as well as others. Each new shale play is unique in nature with respect to geologic setting, lithology, and production mechanism. It is useful to have a defined strategy for the discovery, development, and decline phases of each individual shale play. The roadmap to shale well-completion designs should include the following key factors:
Fracability: capability of the reservoir to be fracture stimulated effectively
Producibility: capability of the completion plan to sustain commercial production
Sustainability: capability of the field development to meet both economic and environmental constraints
This paper reviews the evolution and development of completion practices of the major US shale reservoirs in the last two decades and presents a roadmap for effective completion practices for shale stimulation. The completion roadmap uses the history of 16,000 shale frac stages in the Barnett, Woodford, Haynesville, Antrim, and Marcellus shales. Following the map through specific decision points will alter the path for individual shales. These decision points will be influenced by geologic, geochemical, and geomechanical information gathered along the way. The path toward a commercially viable shale play from the early asset- evaluation phase to the late asset maintenance-and-remediation phase evolves from a series of decision trees throughout the process.
Information presented in this paper provides a completion engineer with better understanding of the factors involved in shale- play stimulation and provides a methodical approach to select appropriate and optimum solutions that have evolved during the last two decades.