Publication | Closed Access
An Analysis of Power Generation Prospects from Enhanced Geothermal Systems
170
Citations
0
References
2005
Year
Unknown Venue
EngineeringEnergy EfficiencyEnergy ConversionHydrologic EngineeringWell StimulationPower Generation ProspectsEarth ScienceReservoir EngineeringFluid PropertiesPower PlantEnergy GenerationHydraulic StimulationPower GenerationElectrical EngineeringReservoir SimulationGeothermal SystemsRock PropertiesGeothermal Power StationsHydrothermal SystemSustainable EnergyEnergy TransitionCivil EngineeringGeothermal SystemGeomechanicsGeothermal DrillingGeothermal EnergyHydrothermal Geochemistry
Enhanced Geothermal Systems (EGS), also called hot dry or hot fractured rock, are low‑permeability reservoirs such as the Desert Peak site with 210 °C, 2 % porosity, and 1 mD permeability, and the study’s findings are broadly applicable to similar projects. The study analyzes the power‑generation potential of hydraulically stimulated EGS reservoirs with subcommercial permeability. The authors numerically simulate net electrical power output over 20–30 years for doublet, triplet, and five‑spot EGS configurations, modeling the stimulated zone as a double‑porosity system with constant hydraulic properties while varying thickness, fracture spacing, permeability, and injector‑producer spacing.
This paper presents an analysis of power generation prospects from Enhanced Geothermal Systems (EGS), specifically, reservoirs with subcommercial permeability enhanced by hydraulic stimulation. EGS is also known as “hot dry rock” or “hot fractured rock” systems. The performance under consideration here is the net electrical power delivered as a function of time over the 20-to-30 year life of a power plant. Although the parameters in this exercise generally reflect conditions encountered at the Desert Peak EGS project in the State of Nevada, United States, the conclusions are applicable, at least qualitatively, to any EGS project. The analysis relies on numerical simulation of three types of EGS set-ups: (a) doublet (an injection and production well pair), (b) triplet (an injector flanked by a production well on each side), and (c) five-spot (an injector at the center and a production well at each corner of a square). Desert Peak EGS site is a low-permeability fringe of a hydrothermal system with a temperature of 210°C and preenhancement porosity and permeability values of 2% and 1 millidarcy, respectively. The stimulated volume within the system is modeled as a double-porosity system (that is, matrix blocks separated by fractures), and the hydraulic characteristics of the reservoir are assumed to remain constant following enhancement. The assumed thickness of the stimulated zone was varied from 150 to 1,200m, and a range of fracture spacings (from 0.33 to 300m) and fracture permeabilities (from 1 to 100 millidarcy) following enhancement was considered. The spacing between the injector and producers was also varied.