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Basin-Scale Analysis, Management Tools, and Options for Produced Water from Tight-Gas Sand Reservoirs, Uinta Basin, Utah


The production and disposal of water from tight-sand gas reservoirs in the eastern Uinta Basin, Utah, and elsewhere affects the economics of gas resource development and has recently become a topic of much public debate because produced water is the largest-volume waste stream associated with these unconventional gas plays. Managing produced water can be a significant cost fraction of the value of the gas extracted, so there is an economic incentive to minimize this waste stream, and/or generate revenue from treating and reusing produced water in hydrocarbon production or other applications. Balancing the water-use needs and produced-water disposal requirements associated with shale/tight-sand gas development creates significant material handling challenges to both industry and regulators. These challenges are complicated by an operating environment where many individual producers of varying sizes exist within a field, each with varying water needs and production, and a production timescale of decades for the basin as wells play out and new ones are completed. Over 328 BCFG and nearly 50 million bbls of water were produced from the Uinta Basin in 2012. The major tight-gas sand reservoirs in the basin are the Tertiary (Eocene) Wasatch Formation and several formations in the Cretaceous Mesaverde Group. Potential uses for the produced water from these formations include water flooding for secondary recovery, drilling mud formulation, hydraulic fracturing fluid for well completion, and future oil shale production. In addition, some produced water has potential for geothermal energy production. Our study consists of four major components: (1) compilation and analysis of past and new information on the thickness, structure, depth, lithology, water quality, and temperature of all aquifer/reservoir units in the basin from the surface (alluvial) down through the Jurassic Glen Canyon Group; (2) statistical analysis of water production quantity and quality to identify and forecast volume trends for each discrete tight-sand gas-producing interval; (3) development of alluvial aquifer sensitivity/vulnerability models to potential contamination from fluids associated with tight-sand gas development; and (4) an evaluation of the existing infrastructure for produced water management/reuse and recommendations for best management practices and the energy generation potential of geothermal-produced waters.