Post on 12-Feb-2021
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