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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

An

nu

al 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