An Alternative and Modular Approach to Enhanced Geothermal Systems

Basic Information
Author: Horne, R.N., Butler, S.J., Granados, E.E., and Sanyal, S.K.
Description:This paper describes a low-risk, low-cost and modular alternative to the conventional Hot Dry Rock or Enhanced Geothermal Systems (EGS). In this approach, which we have named the Earth Energy Extraction System (Triple-E System), the injected fluid is allowed to get preheated in the injection well bore before reaching the reservoir; this preheating is achieved through injection in ultra-slim diameter wells (2.5 to 7.5cm) and by keeping the rate of injection very low (on the order of 10 liters per second). The injected fluid then heats up further as it travels to the production well through pores and fractures in the rock.The injection wells are terminated close to and at a shallower level than the top of the productive interval in the production well. This approach avoids the two main technical limitations associated with conventional EGS: (a)creating a significant reservoir volume by artificial fracturing; and (b) fluid loss control. This approach reduces dependence on the occurrence of natural permeability that limits the scope of conventional geothermal technology.The risk of cooling of the production well by short circuiting of injected water, a common concern in both EGS and conventional geothermal projects, is significantly reduced by preheating of the injected water.
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Organization Name: Arizona Geological Survey
Street: 416 W. Congress St. Ste. 100
City: Tucson
State: Arizona
Zip: 85701
Phone: 520-770-3500
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North Bounding Latitude: 42.1364596585
South Bounding Latitude: 32.219233665
East Bounding Longitude: -113.704413794
West Bounding Longitude: -125.130195044