Natural analogs for enhanced heat recovery from geothermal systems

PDF Version Also Available for Download.

Description

High-temperature hydrothermal systems are physically and chemically zoned with depth. The energy input is from a magmatic zone, intruded by igneous bodies, that may also contribute variable amounts of magmatic fluid to the system. The heat source is directly overlain by a section of rocks, that due to their elevated temperature, respond to stress in a ductile fashion. The ductile zone is, in turn, overlain by a section of rocks that respond to stress in a brittle fashion, where water is able to circulate through fractures (the geothermal reservoir) and will be termed the hydrothermal circulation zone. Ancient and modern ... continued below

Physical Description

43-49

Creation Information

Nielson, Dennis L. January 24, 1996.

Context

This article is part of the collection entitled: Office of Scientific & Technical Information Technical Reports and was provided by UNT Libraries Government Documents Department to Digital Library, a digital repository hosted by the UNT Libraries. More information about this article can be viewed below.

Who

People and organizations associated with either the creation of this article or its content.

Provided By

UNT Libraries Government Documents Department

Serving as both a federal and a state depository library, the UNT Libraries Government Documents Department maintains millions of items in a variety of formats. The department is a member of the FDLP Content Partnerships Program and an Affiliated Archive of the National Archives.

Contact Us

What

Descriptive information to help identify this article. Follow the links below to find similar items on the Digital Library.

Description

High-temperature hydrothermal systems are physically and chemically zoned with depth. The energy input is from a magmatic zone, intruded by igneous bodies, that may also contribute variable amounts of magmatic fluid to the system. The heat source is directly overlain by a section of rocks, that due to their elevated temperature, respond to stress in a ductile fashion. The ductile zone is, in turn, overlain by a section of rocks that respond to stress in a brittle fashion, where water is able to circulate through fractures (the geothermal reservoir) and will be termed the hydrothermal circulation zone. Ancient and modern high-temperature geothermal systems show a predictable sequence of evolutionary events affecting these stratified zones. Metamorphic core complexes are uplifts, formed in highly extended terrains, that expose fossil brittle-ductile transition zones. Formerly ductile rocks have had brittle fractures superimposed on them, and meteoric hydrothermal systems are associated with the brittle fracturing. Porphyry copper deposits typically evolve from magmatic to meteoric hydrothermal systems. At the Larderello geothermal system, the brittle- ductile transition has been mapped using reflection seismology, and the zone has been penetrated by the San Pompeo 2 well where temperatures >420°C were encountered. Although neo-granitic dikes have been penetrated by drilling in the Larderello area, the brittle- ductile transition is largely above the inferred plutonic heat source. In the Geysers system, in contrast, the present steam system has been superimposed on young plutonic rocks and the inferred brittle-ductile transition is present at a depth of about 4.7 km within the plutonic rocks. As hydrothermal reservoirs are depleted, or surface facilities are restricted by environmental considerations, interest will turn to the deeper portions of known systems. Japan already has an aggressive program to develop Deep-seated and Magma-Ambient resources. This program, as well as others that develop methods for the mining of heat past the stage of primary production, will be termed Enhanced Heat Recovery (EHR). Examples of the evolution of natural systems suggest the methods by which deep geothermal systems can be exploited. The key to the exploitation of deep geothermal systems is successful injection of water into rocks above the brittle-ductile transition, producing steam, cooling the rocks and driving the brittle-ductile transition to deeper levels. Under this scenario, injection wells may be more expensive and require more thoughtful planning than production wells.

Physical Description

43-49

Subjects

Source

  • Proceedings, Twenty-First Workshop on Geothermal Reservoir Engineering, Stanford University, Stanford, CA, January 22-24, 1996

Language

Item Type

Identifier

Unique identifying numbers for this article in the Digital Library or other systems.

  • Report No.: SGP-TR-151-7
  • Grant Number: None
  • Office of Scientific & Technical Information Report Number: 889706
  • Archival Resource Key: ark:/67531/metadc884557

Collections

This article is part of the following collection of related materials.

Office of Scientific & Technical Information Technical Reports

Reports, articles and other documents harvested from the Office of Scientific and Technical Information.

Office of Scientific and Technical Information (OSTI) is the Department of Energy (DOE) office that collects, preserves, and disseminates DOE-sponsored research and development (R&D) results that are the outcomes of R&D projects or other funded activities at DOE labs and facilities nationwide and grantees at universities and other institutions.

What responsibilities do I have when using this article?

When

Dates and time periods associated with this article.

Creation Date

  • January 24, 1996

Added to The UNT Digital Library

  • Sept. 21, 2016, 2:29 a.m.

Description Last Updated

  • Dec. 8, 2016, 8:45 p.m.

Usage Statistics

When was this article last used?

Congratulations! It looks like you are the first person to view this item online.

Interact With This Article

Here are some suggestions for what to do next.

Start Reading

PDF Version Also Available for Download.

Citations, Rights, Re-Use

Nielson, Dennis L. Natural analogs for enhanced heat recovery from geothermal systems, article, January 24, 1996; United States. (digital.library.unt.edu/ark:/67531/metadc884557/: accessed October 19, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.