The Role of Wrench Faults and Fractures in Creating “Sweet Spots” in Tight Gas Exploration and Production at Rulison Field, Colorado
Thomas L. Davis, Robert D. Benson, 2013. "The Role of Wrench Faults and Fractures in Creating “Sweet Spots” in Tight Gas Exploration and Production at Rulison Field, Colorado", Application of Structural Methods to Rocky Mountain Hydrocarbon Exploration and Development, Constance N. Knight, Jerome J. Cuzella, Leland D. Cress
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Study of a regional three-dimensional seismic data set by Cumella and Ostby (2003) indicated the potential existence of wrench faults in the southern Piceance Basin, Colorado. Although the faults could be inferred to cut through the productive interval, no direct observation was possible until the Reservoir Characterization Project (RCP) conducted a multicomponent seismic study at Rulison Field. This study confirms the existence of faults and coduments their importance in creating fracture zones critical to higher expected ultimate recovery (EUR) well production within the field. Three-dimensional seismic data were acquired at Rulison Field by RCP to investigate whether zones of high fracture density within the Mesaverde reservoir interval could be detected. Three time-lapse, multicomponent seismic surveys were acquired in 2003, 2004, and 2006. The study confirmed the existence of wrench faults, documented zones of high fracture density, and observed pressure depletion within these zones. Wrench faults and fracture zones play an important role in the creation of “sweet spots” associated with wells of high EUR. Sweet spot identification with multicomponent seismic data can improve the economics of tight gas exploration and production.
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With increasing industry emphasis on developing “unconventional” tight gas reservoirs and on enhancing recovery from existing fields, geologists are facing diverse challenges in the applications of structural geology. Identifying fracture characteristics within petroleum systems is essential. Understanding the timing of tectonics and the formation of structures is important, as these factors strongly influence hydrocarbon generation, migration, entrapment, and preservation. The purpose in publishing this collection of key papers is to aid future workers in addressing complex interrelationships between structural geology and hydrocarbon exploration and development. The first four chapters of this book focus on structural concepts and techniques. The second part of this book is a collection of Rocky Mountain fault and fracture studies. These well documented studies are valuable reference materials for all petroleum geologists.