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Society of Petroleum Engineers Distinguished Lecturer Programwww.spe.org/dl
Heat Mining at The Geysers Geothermal Field Using Reclaimed Wastewater
Marina Voskanian, P. E.California State Lands CommissionSociety of Petroleum
Engineers Distinguished Lecturer Programwww.spe.org/dl
The views expressed in this presentation are those of the author, and do not necessarily reflect those of the State Lands Commission or its staff.
Overview• History
• Need for innovative solutions
• Government-industry collaboration
• Two injection projects
• Effect on induced seismicity
• Environmental benefits
• Worldwide applications2
(1000 MWe)
The Geysers Geothermal Field
3
The Geysers Geothermal Field History
• Discovered in 1847
• Largest geothermal field in the world
• Peak field development in 1987 generating 1500 Megawatts
• Steep production decline:Reservoir pressureSteam source
4
• 450 wells • 50 injection wells• 18 power plants
• 1000 Megawatt capacity • Equivalent to 60% of the power
demand for the Coastal Region
Current Status
The Geysers Geothermal Field
5
Geothermal Heat Mining System
H2O
Surface Power Plant
Microseismic Monitoring
Fractured Reservoir
Deep Wells
Injection Well
Production Well
6
Additional Water Injection
• Need for pressure maintenance
• Plant condensate not sufficient for heat mining • Injection reduces Non-Condensable Gas production
(NCG)
• Tracer tests confirm water injection supplements steam production
7
Government-Industry Collaboration
• Need for discharge of treated sewage water:• Lake County• City of Santa Rosa• Other Municipalities
• Environmental benefits of disposing effluent water into the Geysers
• Partnership between public and private sectors
8
Two Injection Projects
• Southeast Geysers Effluent Pipeline (SEGEP)
• Santa Rosa Geysers Recharge Pipeline (SRGRP)
9
The Geysers Geothermal Resource Area with the Lake County and Santa Rosa Injection Zones
10
Southeast Geysers Effluent Pipeline Project (SEGEP)
• Delivered lake water and secondary treated water from Lake County Sanitation District
• Increased field wide mass replacement from 28% to 50%
• Benefit estimated at 69 MWe of additional power
11
Santa Rosa Recharge Geysers Pipeline (SRGRP)
• Delivered tertiary treated water from treatment plant from City of Santa Rosa for injection
• Benefit estimated at 85 MWe of additional power
• Increased mass replacement to 85%
• Remaining water used for:• Agriculture• Urban irrigation
12
Combined Generation History of All Calpine Geysers Plants- GWh
0
1,000
2,000
3,000
4,000
5,000
6,000
7,000
8,000
9,000
10,000
01/01/91
01/01/92
12/31/92
12/31/93
01/01/95
01/01/96
12/31/96
12/31/97
01/01/99
01/01/00
12/31/00
12/31/01
01/01/03
01/01/04
12/31/04
12/31/05
01/01/07
01/01/08
12/31/08
12/31/09
01/01/11
Year
Ann
ual G
ener
atio
n, G
Wh
Entire Geysers FieldGain = 154 mw
Extrapolation at 3% harmonic based on 99-2000 data
Calpine Fieldwide Benefits
13
Calpine Geysers Production and Injection History
14
5,6
7,89,10
1112
13,14 17
18Son
20, 16
WFFBC
Aid
0
50
100
150
200
250
1969 1971 1973 1975 1977 1979 1981 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 2003 2005 2007 2009 2011
BIL
LIO
N P
OU
ND
S
CALPINE GEYSERS PRODUCTION AND INJECTION HISTORY
TOTAL PRODUCTION CONDENSATE CREEK SEGEP SRGRP
Cal
Water Injection Management• Where to inject?• How much to inject?
InjectionProduction
15
Injection Management Techniques
• Fracture characterization
• Heat mining modeling
• Reservoir temperature/pressure• Production decline
• NCG concentration
• Location and operational efficiencies
• Proximity to power plant and water pipeline
16
Induced Seismicity
• Seismically active prior to injection
• Public concern with increasing micro-earthquakes (MEQ)
• Ongoing monitoring by two seismic arrays:United States Geological SurveyLawrence Berkeley National Laboratory
17
Effect of Water Injection on Seismic Activity
18
Water Injection and Induced Seismicity
19
Summary of “Earthquake Potential” Studies
• Earthquakes cannot be predicted
• Earthquake magnitudes depend on surface area of fault that can slip
• Large earthquakes occur mainly in large faults
• No large faults mapped at The Geysers
• It is extremely unlikely that injection activities at The Geysers will lead to large earthquakes
20
Environmental BenefitsClean Energy
13 million gal/day of recycled water injection
100 megawatts
1 million barrels of oil per year
100,000 households21
Environmental BenefitsClean Energy
49 million liters/day of recycled water injection
100 megawatts
119 million liters of oil per year
100,000 households21
ConclusionWorldwide Application
• Successful application of petroleum engineering tools
• Sustained steam production through heat mining
• Additional power generation and revenue
• Identifying opportunities for environmental benefits
• Successful government-industry collaboration
22
Any Questions
23
Society of Petroleum Engineers Distinguished Lecturer Programwww.spe.org/dl
26
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Induced Seismicity Potential in Energy Technologies
Published byNational Academy of Sciences
http://www.nap.edu/catalog.php?record_id=13355#orgs
