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8/20/2019 geothermalinnovative-geopressurized
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GEOFAR : Innovative geothermal technologiesLast modifications: 2009-10-14
Supported by
The sole responsibility for the content of this Factsheet lies with the authors. It does not necessarily reflect theopinion of the European Communities. The European Commission is not responsible for any use that may bemade of the information contained therein.
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GEOPRESSURIZED SYSTEMS
GENERAL PRESENTATION
Context
Geopressured resources are deep reservoirs of high-pressured hot water that contain dissolved natural gas. A
geopressured reservoir is formed in sedimentary formations when water percolates into the pores of a layer of
sand. When non-porous shale settles on top, it traps the fluid into the sand layer at very high pressures. Over
millions of years, this pressure increases even more as additional sedimentary layers build on top of the reservoir.
If the sand body in which the water is trapped is large enough, the reservoir can economically produce energy for
quite a long time. An important characteristic of geopressured reservoirs, at least from an energy perspective, is
that they contain dissolved methane, or natural gas. This, therefore, yields three sources of energy that can be
utilized from the reservoir:
1. Hydraulic energy from extreme pressure
2. Heat energy from the fluid
3. Dissolved natural gas
Comparing to other natural gas reservoirs, the amount of dissolved methane in these types of reservoirs is very
small. For the natural gas alone, the reservoir would be uneconomical. However, with two more sources of
energy, their utilization becomes worthwhile.
A geopressured geothermal facility operates on both natural gas and geothermal fuel. It could also be considered
as a geothermal-fossil fuel hybrid system.
State of the art
A successful demonstration plant operated in US in the 1980’s. The Department of Energy built a demonstration
plant in Texas which produced electricity from geopressured resources. Although it run successfully as a
demonstration, it was not considered economic at the time and was dismantled by the US Department of Energy.
Geothermal solution
In the USA, there is a renewed interest in the energy potential of geopressured geothermal resources. Congress
authorized new technology demonstrations for geopressured geothermal systems in 2007.
Resources of this type exist in the North Sea and can be found in deep ponds in Europe.
FOCUSING ON THE GEOTHERMAL SOLUTION
Current status of the solution
Comments
Scientific Project (only on paper or
under preparation)
Demonstration project One demonstration project was built in the 1980’s. Nowadays new
interests are appearing and another demonstration project is
8/20/2019 geothermalinnovative-geopressurized
2/3
GEOFAR : Innovative geothermal technologiesLast modifications: 2009-10-14
Supported by
The sole responsibility for the content of this Factsheet lies with the authors. It does not necessarily reflect theopinion of the European Communities. The European Commission is not responsible for any use that may bemade of the information contained therein.
2 / 3
currently developed in the USA.
Scientific Pilot
Industrial Pilot
Industrial stage
Other?
Advantages
(1, 2, 3, 4
or 5) *
Comments
Environmental
Economical 4 Multi uses of the resources extracted from one well
Social
ScientificallyOthers
* 1(very few advantageous) to 5(totally advantageous)
Advantages against other applications
For the natural gas alone, the reservoir would be uneconomical. However, with two more sources of energy
(including geothermal heat), their utilization becomes worthwhile.
Focusing on Economic Feasibility
- Estimated costsIt is impossible to make generalities about the costs due to the character of the project.
- Impact on profitability
Geopressured geothermal resources have not been tapped since they were successfully demonstrated almost
two decades ago, when oil and gas costs were low. Today’s increasing oil and gas costs make the economics of
geopressured applications look particularly promising.
However, American researchers argue that a fresh approach to geopressured resources is called for. Advanced
technology, coupled with greater need for domestic energy and higher values for both electricity and natural gas,
could result in economical production from the substantial geopressured resource base.
EXAMPLES/CASE STUDIES
Location
Demonstration Project: Pleasant Bayou (Texas, USA)
Technical characteristics of the operation
The US Department of Energy embarked on a project to demonstrate geothermal geopressured resources in the
1980s at Pleasant Bayou in Texas. The original concept as defined in the DOE document was to tap into three
8/20/2019 geothermalinnovative-geopressurized
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GEOFAR : Innovative geothermal technologiesLast modifications: 2009-10-14
Supported by
The sole responsibility for the content of this Factsheet lies with the authors. It does not necessarily reflect theopinion of the European Communities. The European Commission is not responsible for any use that may bemade of the information contained therein.
3 / 3
forms of energy: heat from the geothermal resource (thermal energy), energy from natural gas in the reservoir
(chemical energy), and well head pressure (mechanical energy). Due to cost considerations, in the Pleasant
Bayou demonstration plant only the thermal and chemical energy were captured. Exhaust heat generated from
the onsite burning of the natural gas was recovered to improve cycle efficiency. The one megawatt geothermalgeopressured project was tested in October through December 1989. The demonstration ran January through
May of 1990. The design power plant output was 905 kW, with slightly over half of the power derived from the gas
engine. Though the capacity factor was decreased due to a 3-day plant outage and a 4-week turbine outage, the
overall plant availability was 97.5 percent. During the 121 days of operation, 3,445 MWh of electricity were sold to
Houston Power and Light.
According to experts associated with the project, there were no major technical problems—carbon deposits
accumulated in the exhaust gas heat exchanger, but these were easily removed. Scale inhibitors were used
successfully to control scale in the production well at the facility.
SOURCES AND CONTACTS
http://www.geo-energy.org/publications/reports.asp