Metadata for reports, compilations, maps, documents, publications, theses, related to geothermal, for the states of Delaware, Georgia, Maryland and Virginia. A spreadsheet with 8 worksheets, including information about the template, notes related to revisions of the template, Resource provider information, the data, a field list (data mapping view) and a worksheet with vocabularies for use in populating the spreadsheet (data valid terms). 191 documents are listed.

To prioritize information for archiving and to determine the applicability of the Fenton Hill experience to the future development of Enhanced Geothermal Systems (EGS), an integrated review was made of five categories of Fenton Hill information: hydraulic fracturing data, well logs, seismic data, flow test data and tracer test data. Major experiments were identified, the methods of data collection and analysis were determined, the location and format of the data were determined, and further analyses that would yield information of value to EGS developers were suggested. Such analyses would be directed toward the determination of: I) if and how the state of stress in the reservoir changed during sequential fracturing jobs; 2) how the orientation of fractures changed with depth and location; 3) how the reservoir size increased as fracturing and flow testing operations proceeded; 4) how the hydraulic properties and heat-transfer characteristics of the reservoir varied with changes in operating conditions; and 5) how the Phase II reservoir (the deeper and hotter of the two reservoirs developed) would behave over the long term under various operating conditions.

Under the premise that the behavior of enhanced geothermal systems (EGS) will be dominated by fracture flow, this paper reviews the special features that would be required of any practical numerical simulator for EGS. These features, required in addition to the basic features of conventional geothermal simulators, namely, the ability to handle two-phase fluid flow, heat transfer and tracer transp0l1 in porous and fractured media, are: explicit representation of fractures, change in fracture aperture due to effective stress and shear, thermo-elastic effects, relation between fracture aperture and conductivity, and channeling of fluid flow within fractures. Chemical reaction between water and rock and coupling of the reservoir model with a well bore model would also be desirable features.

An industry-DOE cost-shared project is underway to evaluate the technical feasibility of developing an EGS power generation project on the eastern side of the Desert Peak geothermal field. An existing well (DP 23-1) is the focus of much of the Phase I investigation, including re-interpretation of lithology, acquisition and analysis of a well bore imaging log, conducting and analyzing a step-rate injection test, performing a "mini-frac" to determine the magnitude of the least principal stress, and re-completing the well in preparation for hydraulic stimulation in Phase II. In addition, numerical modeling has been undertaken to estimate heat recovery and make generation forecasts for various stimulated volumes and well configurations.

The Department of Energy's EGS Strategic Plan anticipates that EGS experimentation in the United States will be underway by 2004 in areas within or adjaeent to commerciallydeveloped hydrothermal fields, and that an EGS demonstration plant will begin operating in 2008. Criteria for selecting sites for EGS experimentation focus on enhancing energy recovery at producing fields while advancing the EGS knowledge base incrementally towards a demonstration project. With input from field operators, basic characteristics and information on the type of EGS work that may be undertaken are presented for 15 producing fields and 2 unexploited fields. Six producing fields meet 90 - 100% of the site selection criteria and 9 meet 60 - 70%. The use of EGS techniques to supply an existing facility has the advantages of low cost, support from the geothermal industry and demonstration of applicability to a variety of conversion technologies. This approach seeks to reduce EGS risk and uncertainty, promoting the transition from research to commercial evelopment.

This paper presents an evaluation of the cost of electric power from Enhanced Geothermal Systems (EGS), that is, reservoirs with sub-commercial permeability enhanced by hydraulic stimulation. The parameters in this exercise reflect the conditions encountered at the Desert Peak EGS project in Nevada, but the results should be applicable, at least qualitatively, to any EGS project. The approach taken is to : 1) use numerical simulation to evaluate energy recovery versus time over an assumed 30-year project life for various system configurations (number and spacing of wells, assumptions about stimulation effectiveness, etc; 2) estimate the levelized power cost for each configuration, based on capital cost, O&M cost, the cost of money and inflation rate (using Monte Carlo sampling to address uncertainties); 3) determining the sensitivity of levelized cost to the cost components, interest and inflation rates, and resource characteristics (maximum practical pumping rate, reservoir characteristics, and the depth to thereservoir at the site); and 4) estimating future EGS costs and considering the possible technology improvements that could be made by that time.

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.

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 wellbore 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 shortcircuiting of injected water, a common concern in both EGS and conventional geothermal projects, is significantly reduced by preheating of the injected water.