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Title: Assessment of the State-Of-The-Art of Numerical Simulation of Enhanced Geothermal Systems

Abstract

The reservoir features of importance in the operation of enhanced geothermal systems are described first (Section 2). The report then reviews existing reservoir simulators developed for application to HDR reservoirs (Section 3), hydrothermal systems (Section 4), and nuclear waste isolation (Section 5), highlighting capabilities relevant to the evaluation and assessment of EGS. The report focuses on simulators that include some representation of flow in fractures, only mentioning other simulators, such as general-purpose programs or groundwater models (Section 6). Following these detailed descriptions, the report summarizes and comments on the simulators (Section 7), and recommends a course of action for further development (Section 8). The references are included in Section 9. Appendix A contains contractual information, including a description of the original and revised scope of work for this study. Appendix B presents comments on the draft report from DOE reviewer(s) and the replies of the authors to those comments. [DJE-2005]

Publication Date:
Research Org.:
GeothermEx, Inc., Richmond, CA; Thunderhead Engineering Consultants, Manhattan, KS; Golder Associates, Redmond, WA
Sponsoring Org.:
USDOE
OSTI Identifier:
860611
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
15 GEOTHERMAL ENERGY; 12 MANAGEMENT OF RADIOACTIVE WASTES, AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; EVALUATION; FRACTURES; GEOTHERMAL SYSTEMS; HYDROTHERMAL SYSTEMS; RADIOACTIVE WASTES; SIMULATION; SIMULATORS; Geothermal Legacy

Citation Formats

None. Assessment of the State-Of-The-Art of Numerical Simulation of Enhanced Geothermal Systems. United States: N. p., 1999. Web.
None. Assessment of the State-Of-The-Art of Numerical Simulation of Enhanced Geothermal Systems. United States.
None. Mon . "Assessment of the State-Of-The-Art of Numerical Simulation of Enhanced Geothermal Systems". United States. doi:. https://www.osti.gov/servlets/purl/860611.
@article{osti_860611,
title = {Assessment of the State-Of-The-Art of Numerical Simulation of Enhanced Geothermal Systems},
author = {None},
abstractNote = {The reservoir features of importance in the operation of enhanced geothermal systems are described first (Section 2). The report then reviews existing reservoir simulators developed for application to HDR reservoirs (Section 3), hydrothermal systems (Section 4), and nuclear waste isolation (Section 5), highlighting capabilities relevant to the evaluation and assessment of EGS. The report focuses on simulators that include some representation of flow in fractures, only mentioning other simulators, such as general-purpose programs or groundwater models (Section 6). Following these detailed descriptions, the report summarizes and comments on the simulators (Section 7), and recommends a course of action for further development (Section 8). The references are included in Section 9. Appendix A contains contractual information, including a description of the original and revised scope of work for this study. Appendix B presents comments on the draft report from DOE reviewer(s) and the replies of the authors to those comments. [DJE-2005]},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Nov 01 00:00:00 EST 1999},
month = {Mon Nov 01 00:00:00 EST 1999}
}

Technical Report:

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  • The current and near-term state of the art of high-temperature (250-365/sup 0/F, 121-185/sup 0/C) geothermal downwell pumps was assessed by investigating the causes of failure of more than 70 lineshaft and electric submersible pumps. Recent developments in novel downwell pumping technology were also reviewed. These data were used to estimate the likely near-term availability factor of high-temperature downwell pump systems. In an industry survey completed in April 1983, it was found that both lineshaft and electric submersible pumps have encountered repeated and severe difficulties when pumping fluids above 250/sup 0/F (120/sup 0/C) in geothermal wells. Sixty-three percent of the lineshaftmore » and 83% of the electric submersible pumps failed. The average run life was less than two months. However, both lineshaft and electric submersible pumps have undergone recent developments that strongly suggest that a significant improvement has occurred. Near-term lives were estimated based on engineering judgment in light of recent developments. It was concluded that near-term and electric submersible pumps will have a probable average run life of 6-12 months in resources up to 365/sup 0/F (185/sup 0/C). Statistical modeling showed that if average run lives reach 6-12 months as expected, then the near-term pumping technology is capable of providing reliable brine supply to a large geothermal binary plant.« less
  • The state-of-the-art of geothermal liquid waste disposal is reviewed and surface and subsurface disposal methods are evaluated with respect to technical, economic, legal, and environmental factors. Three disposal techniques are currently in use at numerous geothermal sites around the world: direct discharge into surface waters; deep-well injection; and ponding for evaporation. The review shows that effluents are directly discharged into surface waters at Wairakei, New Zealand; Larderello, Italy; and Ahuachapan, El Salvador. Ponding for evaporation is employed at Cerro Prieto, Mexico. Deep-well injection is being practiced at Larderello; Ahuachapan; Otake and Hatchobaru, Japan; and at The Geysers in California. Allmore » sites except Ahuachapan (which is injecting only 30% of total plant flow) have reported difficulties with their systems. Disposal techniques used in related industries are also reviewed. The oil industry's efforts at disposal of large quantities of liquid effluents have been quite successful as long as the effluents have been treated prior to injection. This study has determined that seven liquid disposal methods - four surface and three subsurface - are viable options for use in the geothermal energy industry. However, additional research and development is needed to reduce the uncertainties and to minimize the adverse environmental impacts of disposal. (MHR)« less
  • Existing state-of-the-art technologies for removal of hydrogen sulfide are discussed along with a comparative assessment of their efficiencies, reliabilities and costs. Other related topics include the characteristics of vapor-dominated and liquid-dominated resources, energy conversion systems, and the sources of hydrogen sulfide emissions. It is indicated that upstream control technologies are preferred over downsteam technologies primarily because upstream removal of hydrogen sulfide inherently controls all downstream emissions including steam-stacking. Two upstream processes for vapor-dominated resources appear promising; the copper sulfate (EIC) process, and the steam converter (Coury) process combined with an off-gas abatement system such as a Stretford unit. For liquid-dominatedmore » systems that produce steam, the process where the non-condensible gases are scrubbed with spent geothermal fluid appears to be promising. An efficient downstream technology is the Stretford process for non-condensible gas removal. In this case, partitioning in the surface condenser will determine the overall abatement efficiency. Recommendations for future environmental control technology programs are included.« less
  • The purpose of this report is to lay the groundwork for an emerging process to assess U.S. geothermal resources that might be suitable for development as Enhanced Geothermal Systems (EGS). Interviews of leading geothermists indicate that doing that will be intertwined with updating assessments of U.S. higher-quality hydrothermal resources and reviewing methods for discovering ''hidden'' hydrothermal and EGS resources. The report reviews the history and status of assessment of high-temperature geothermal resources in the United States. Hydrothermal, Enhanced, and Hot Dry Rock resources are addressed. Geopressured geothermal resources are not. There are three main uses of geothermal resource assessments: (1)more » They inform industry and other interest parties of reasonable estimates of the amounts and likely locations of known and prospective geothermal resources. This provides a basis for private-sector decisions whether or not to enter the geothermal energy business at all, and for where to look for useful resources. (2) They inform government agencies (Federal, State, local) of the same kinds of information. This can inform strategic decisions, such as whether to continue to invest in creating and stimulating a geothermal industry--e.g., through research or financial incentives. And it informs certain agencies, e.g., Department of Interior, about what kinds of tactical operations might be required to support such activities as exploration and leasing. (3) They help the experts who are performing the assessment(s) to clarify their procedures and data, and in turn, provide the other two kinds of users with a more accurate interpretation of what the resulting estimates mean. The process of conducting this assessment brings a spotlight to bear on what has been accomplished in the domain of detecting and understanding reservoirs, in the period since the last major assessment was conducted.« less