GEOTHERMALPOWER

Ken Williamson

General Manager,Geothermal Technology & Services,

Unocal Corporation

WORKSHOP ON SUSTAINABLE ENERGY SYSTEMSNovember 29 - December 1, 2000

Georgia Tech, Atlanta, GA

GEOTHERMALGEOTHERMALPOWERPOWER

Ken WilliamsonKen Williamson

General Manager,General Manager,Geothermal Technology & Services,Geothermal Technology & Services,

Unocal CorporationUnocal Corporation

WORKSHOP ON SUSTAINABLE ENERGY SYSTEMSNovember 29 - December 1, 2000

Georgia Tech, Atlanta, GA

Heat in the EarthHeat in the Earth (Rybach et al., 2000)(Rybach et al., 2000)

!! Stored in the earthStored in the earth 10 103131 J J

!! Beneath continents (

Geothermal Power WorldwideGeothermal Power Worldwide

!! 8 GW8 GWee in 21 nations in 21 nations

!! 50 TWh 50 TWh generated in 1999

! In the last 5 years:– Worldwide increased by 17%

– U.S. decreased 20%

Geothermal Power in U.S.Geothermal Power in U.S.0.38% of Country’s Generation0.38% of Country’s Generation

!! CaliforniaCalifornia 2,294 MW2,294 MW

!! NevadaNevada 196 MW 196 MW

!! HawaiiHawaii 25 MW 25 MW

!! UtahUtah 31 MW 31 MW

!! TOTAL TOTAL 2,400 MW2,400 MW

HIG H ENTHALPY FIELDS & PRO SPEC TSHIG H ENTHALPY FIELDS & PRO SPEC TS

Pacific“Ring of

Fire”

Pacific“Ring of

Fire”

Exploration

“Oil seep” analogy

Geothermal Fields Developed byGeothermal Fields Developed byUnocalUnocal

GeysersGeysers

1100 MW1100 MW

IndonesiaIndonesia

330 MW330 MW

PhilippinesPhilippines

756 MW756 MWSalton SeaSalton Sea

80 MW80 MW

Geothermal BasicsGeothermal BasicsExtracting the Heat CommerciallyExtracting the Heat Commercially

!! Water transports heat to surfaceWater transports heat to surface

!! Naturally fractured rock permits circulationNaturally fractured rock permits circulation

!! Drill to reach at least 200° CDrill to reach at least 200° C

!! Future technology may use man-madeFuture technology may use man-madefracturesfractures

GEOTHERMAL RESOURCE TYPESGEOTHERMAL RESOURCE TYPES

!! Liquid-Liquid-dominateddominated

!! Vapor-Vapor-dominateddominated

!! Low EnthalpyLow Enthalpy

!! Hot Dry RockHot Dry Rock

Example: Vapor-DominatedExample: Vapor-DominatedHigh Enthalpy ResourceHigh Enthalpy Resource

Unocal at The GeysersUnocal at The Geysers1967 -19991967 -1999

380 wells drilled2.5 trillion lbs steam produced124 billion kWh generated

186 million bbl oil equiv.

Example: Liquid-DominatedExample: Liquid-DominatedHigh Enthalpy ResourceHigh Enthalpy Resource

Medan

S u m a t r a

Kalimantan Sulawesi

Jakarta

SALAK PROJECT

330 MW

JAVA

SALAK PROJECT

INDEX MAP

100KM0

SCALE 1:30.000.000

Unocal 330 MW in Java, Indonesia

Liquid-dominated 225 - 310º C

1 - 3 km deep

CROSS-SECTION THROUGH AWIBENGKOK FIELD

During Project Life:

Produce >10 12 lbs steam

Inject 16 billion bbl brine

TurbineandGenerator

Proposed Research TimelineProposed Research Timeline2000 - 20302000 - 2030

»» Optimize exploited geothermal systems &Optimize exploited geothermal systems &reduce development cost of high enthalpy systemsreduce development cost of high enthalpy systems

»» Locally enhance permeability in the tight marginsLocally enhance permeability in the tight marginsof existing systems (EGS)of existing systems (EGS)

»» Explore for and develop “hidden” highExplore for and develop “hidden” highenthalpy systems, with no surface featuresenthalpy systems, with no surface features

»» Develop impermeable systems withDevelop impermeable systems withartificial fracturing (HDR)artificial fracturing (HDR)

-----> Time-----> Time

Optimize exploited geothermalOptimize exploited geothermalsystemssystems

Life Cycle of a Geothermal FieldLife Cycle of a Geothermal Field(Lovekin, 1998)(Lovekin, 1998)

Time ---->

develop maintain decline sustain

MW

OpportunityOpportunity

!! Only a fraction (~20%) of available heat isOnly a fraction (~20%) of available heat iscurrently extracted from a high enthalpycurrently extracted from a high enthalpyreservoirreservoir

!! Smart injection management could greatlySmart injection management could greatlyincrease efficiency and longevityincrease efficiency and longevity

!! The Salak “natural laboratory” presents aThe Salak “natural laboratory” presents aunique opportunity to examine fractured-unique opportunity to examine fractured-system behaviorsystem behavior

ChallengeChallenge

!! Reservoirs have km-scale fracturing:Reservoirs have km-scale fracturing:»» hard to map permeability at km-scalehard to map permeability at km-scale

»» heat transfer properties poorly knownheat transfer properties poorly known

»» current models inadequatecurrent models inadequate

!! Injected liquids are channeled along fracturesInjected liquids are channeled along fracturesand heat sweep is inefficientand heat sweep is inefficient

Re se a rc h:Re se a rc h:

C ha ra c te rize p e rm e a b ility a nd he a tC ha ra c te rize p e rm e a b ility a nd he a ttra nsfe r in fra c ture d syste m stra nsfe r in fra c ture d syste m s

Image Log: Salak Well FMIImage Log: Salak Well FMI

12

U1,2,3

U4,5,6

0 1 Km

Salak Tracer pathways

AWI 4-1 TRACER RETURNS AT AWI 1 WELLS

0 .0

0 .5

1 .0

1 .5

2 .0

2 .5

3 .0

3 .5

- 2 0 0 20 40 60 80 10 0

Elapsed Tim e s ince Dye Injection on 1/8/99, day

Co

nce

ntr

atio

n, p

pb

1-3

1-4

1-5

1-6

1-7

Tracer Returns at Salak

Proposed Research:Proposed Research:Designer tracer cocktailsDesigner tracer cocktails

!! average path temperatureaverage path temperature

!! maximum path temperaturemaximum path temperature

!! surface contact area along flow pathsurface contact area along flow path

SALAK NUMERICAL MODEL FEATURES

WESTERNOUTFLOW

NORTHERN OUTFLOW

SOUTHERN OUTFLOW

SHALLOWEASTERN RESERVOIR

DEEP WESTERNRESERVOIR

Technical Challenge:Technical Challenge:

Combine sparse, complexCombine sparse, complexdata to predict heat sweep indata to predict heat sweep innaturally fractured systemsnaturally fractured systems

Reduce development cost of highReduce development cost of highenthalpy systemsenthalpy systems

Reducing development costsReducing development costs

!! Drilling TechnologyDrilling Technology

!! Energy Conversion TechnologyEnergy Conversion Technology

ChallengesChallenges

!! Need active continuous drillingNeed active continuous drillingprograms to create improvements inprograms to create improvements indrillingdrilling

!! Geothermal industry too small to attractGeothermal industry too small to attractresearch in service companiesresearch in service companies

!! Geothermal turbines are not designedGeothermal turbines are not designedand built in the U.S.and built in the U.S.

OpportunitiesOpportunities

!! SandiaSandia and developers collaborate in and developers collaborate indrilling technologydrilling technology

!! Remarkable drilling improvements haveRemarkable drilling improvements haveoccurred - more are possibleoccurred - more are possible

Drilling Cost Reduction at SalakDrilling Cost Reduction at Salak

75

64

44

27

0

10

20

30

40

50

60

70

80

Units 1 & 2 1995 1996 1997

DAYS PER WELLAWIBENGKOK EXPANSION

GeothermalGeothermal

The BenefitsThe Benefits

Power Plant COPower Plant CO22 Emissions Emissions

0100200300400500600700800900

1000

CO

2 (k

g/M

Wh

) Coal

Oil

Natural Gas

UnocalGeothermal

Fossil fuel data from Goddard and Goddard (1990)Unocal data includes The Geysers

Capacity FactorsCapacity Factors

Source: DOE/Energy Information Agency: data for 1996Source: DOE/Energy Information Agency: data for 1996

0

20

40

60

80

100

WindWind SolarSolar Conv.Conv. AverageAverage Biomass/Biomass/ FossilFossil GeothermalGeothermal

HydroHydro MSWMSW

PercentagePercentage

U.S. Government RoyaltiesU.S. Government Royalties

0

50

100

150

200

W ind Solar Biomass G eothermal

$ Millions$ Millions

ConclusionsConclusions

!! Ultimate geothermal resource is hugeUltimate geothermal resource is huge

!! Present research focus should be:Present research focus should be:–– extend life of existing fields,extend life of existing fields,

–– reduce cost of developing new high enthalpyreduce cost of developing new high enthalpyprojectsprojects

!! Artificially stimulated systems (HDR/EGS)Artificially stimulated systems (HDR/EGS)hold greatest opportunity in the long termhold greatest opportunity in the long term

!! HDR/EGS research should focus onHDR/EGS research should focus ontechnology which can be tested in existingtechnology which can be tested in existingfieldsfields

The End