dr. hendra grandis geofisika - itb file1 geophysics for geothermal exploration dr. hendra grandis...
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Geophysics for Geophysics for Geothermal ExplorationGeothermal Exploration
Dr. Hendra GrandisDr. Hendra GrandisGeofisika Geofisika -- ITBITB
AgendaAgenda
Basic concept of GeophysicsBasic concept of Geophysics: Review: Review
Geophysical signatures of a geothermal systemGeophysical signatures of a geothermal system
Geophysical methods for geotermal explorationGeophysical methods for geotermal exploration
ExamplesExamples
Discussion, Q/ADiscussion, Q/A
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Basic concepts of GeophysicsBasic concepts of Geophysics
Major task of geophysics is to make quantitative Major task of geophysics is to make quantitative statements about the interior of the earth statements about the interior of the earth ((modelmodel) from observation () from observation (datadata))
Data Data subsurface physical propertysubsurface physical property
Geophysical methods: Geophysical methods:
gravity, magnetics, geogravity, magnetics, geo--electrics, electrics, electromagnetics, seismics, ...electromagnetics, seismics, ...
data data processingprocessing
field field datadata
measurementmeasurement
signal / Earthsignal / Earth’’s Responses Response((observobserved ed parameterparameterss))
Basic concepts of GeophysicsBasic concepts of Geophysics
subsurface subsurface modelmodel
interpretainterpretattiionon
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Basic concepts of GeophysicsBasic concepts of Geophysics
Basic concepts of GeophysicsBasic concepts of Geophysics
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Elements of a geothermal systemElements of a geothermal system
Heat source Heat source (magmatic)(magmatic)
ReservoirReservoir
Cap rockCap rock
Recharge Recharge systemsystem
Isotherms
Smectite Clay
1 KM1:1
PropyliticAlteration in
FracturedGeothermalReservoir
Heat and Gasfrom Magma
Unaltered
BasinClays
ChlorideSpring
Acid SulphateFumarole
(Cumming Geoscience)
Role of GeophysicsRole of Geophysics
Role of geophysics is to identify each element of Role of geophysics is to identify each element of a geothermal systema geothermal system→→ geometrygeometry
→→ lithologylithology
→→ conceptual conceptual modelmodel
Isotherms
Smectite Clay
1 KM1:1
PropyliticAlteration in
FracturedGeothermalReservoir
Heat and Gasfrom Magma
Unaltered
BasinClays
ChlorideSpring
Acid SulphateFumarole
(Cumming Geoscience)
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Role of GeophysicsRole of Geophysics
Exploration of a geothermal system is a multiExploration of a geothermal system is a multi--disciplinary approachdisciplinary approach→→ Geology and GeochemistryGeology and Geochemistry→→ GeophysicsGeophysics→→ Drilling and Reservoir EngineeringDrilling and Reservoir Engineering
Geophysical signaturesGeophysical signatures
Gravity and magneticGravity and magneticss→→ grossgross--structure of a geothermal system structure of a geothermal system
(caldera / rim structure, pull(caldera / rim structure, pull--apart basin or apart basin or shear zone, etc.)shear zone, etc.)
→→ heat source (magmatic intrusion)heat source (magmatic intrusion)
GeoGeo--electricalelectrical→→ cap rockcap rock→→ reservoir zonereservoir zone
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Geophysical signaturesGeophysical signatures
SelfSelf--PotentialPotential→→ fluid movement (upfluid movement (up--flow, inflow, in--flow)flow)→→ fracture zonefracture zone→→ fluid movement (production, reinjection fluid movement (production, reinjection
process)process)monitoringmonitoring -- reservoir managementreservoir management
MicroMicro--seismicseismicss→→ fracture zonefracture zone→→ reservoir changesreservoir changes
Geophysical Techniques Geothermal ExplorationGeophysical Techniques Geothermal Exploration
Standard:Standard: MT, TMT, T--MT, TDEM, GravityMT, TDEM, Gravity
Legacy:Legacy: DipoleDipole--Dipole, Tensor DipoleDipole, Tensor Dipole--BipoleBipole
Special:Special: VES, AMT, CSAMT, SP, HEMVES, AMT, CSAMT, SP, HEMAeromagnetics, Precision Ground MagneAeromagnetics, Precision Ground Magneticstics
Research:Research: Reflection / Refraction SeismicReflection / Refraction SeismicSpecial ApplicationsSpecial Applications
Development:Development: Microgravity, Microearthquake, SubsidenceMicrogravity, Microearthquake, Subsidence
Proprietary:Proprietary: EE--Scan, EScan, E--Map Map
UnreviewedUnreviewed:: AquatrackAquatrack
Suspect:Suspect: Seismic Noise, Low Res Ground Magnetics Seismic Noise, Low Res Ground Magnetics Plausible methods with weak technical Plausible methods with weak technical supportsupport
(Cumming Geoscience)
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Problem / site specificProblem / site specific
Exploration strategyExploration strategy
→→ start with start with ““inexpensiveinexpensive”” or conventional or conventional methods to cover vast area methods to cover vast area (reconnaissance)(reconnaissance)
→→ delineate anomalous zonedelineate anomalous zone
→→ followfollow--up with specialized method for up with specialized method for detailed targetingdetailed targeting
GeophysicGeophysical Survey Designal Survey Design
Development strategyDevelopment strategy
→→ start from a specific area to a larger area, to start from a specific area to a larger area, to explore possibilities from existing (known) explore possibilities from existing (known) information information
GeophysicGeophysical Survey Designal Survey Design
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Typical Typical Geophysical Geophysical SurveySurveyss
Reconnaissance Reconnaissance →→ Gravity Gravity ((and magneticand magnetic))→→ GeoGeo--electrical electrical ResistivityResistivity Sounding and Sounding and
Mapping Mapping
Advanced Advanced →→ MagnetotelluricsMagnetotellurics (MT), Time Domain EM (MT), Time Domain EM
(TDEM)(TDEM)→→ MicroMicro--SeismicsSeismics
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Alteration Alteration –– Resistivity Resistivity
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transmitter generates time transmitter generates time varyingvarying EM fieldEM field
↓↓induces induces Eddy currentsEddy currents in the in the conductor (Earth)conductor (Earth)
↓↓generate secondarygenerate secondarymagnetic fieldmagnetic field
↓↓electric and magnetic fieldselectric and magnetic fieldsare sensed at the receiverare sensed at the receiver
Electromagnetic InductionElectromagnetic Induction
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natural natural electromagnetic fieldelectromagnetic field
MagnetotelluricsMagnetotellurics(MT)(MT)
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MT time seriesMT time series
1E-3 1E-2 1E-1 1E+0 1E+1 1E+2 1E+3
PERIOD (sec.)
1E+0
1E+1
1E+2
1E+3
APP
. RES
ISTI
VITY
(Ohm
.m)
0
45
90
PHA
SE (d
eg.)
1E-3 1E-2 1E-1 1E+0 1E+1 1E+2 1E+3
PERIOD (sec.)
obs. data
calc. data
1E+0 1E+1 1E+2 1E+3
RESISTIVITY (Ohm.m)
1E+2
1E+3
1E+4
1E+5
DEP
TH (m
)
11--D MT smooth modelingD MT smooth modeling
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22--D and 3D and 3--D interpretation of MT data D interpretation of MT data in the in the BajawaBajawa geothermal field Flores, Indonesia geothermal field Flores, Indonesia (Uchida et al., 2002)(Uchida et al., 2002)
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22--D and 3D and 3--D interpretation of MT data D interpretation of MT data in the in the BajawaBajawa geothermal field Flores, geothermal field Flores, Indonesia (Uchida et al., 2002)Indonesia (Uchida et al., 2002)
KarahaKaraha--TelagaTelaga BodasBodas
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The The KarahaKaraha--TelagaTelaga BodasBodasGeothermal System, Indonesia Geothermal System, Indonesia ((RaharjoRaharjo et al., 2002)et al., 2002)
NorthNorth--trending high trending high follows ridge axisfollows ridge axis
Circular gravity high near Circular gravity high near TelagaTelaga BodasBodas
22--D D modellingmodelling
The The KarahaKaraha--TelagaTelaga BodasBodasGeothermal System, Indonesia Geothermal System, Indonesia ((RaharjoRaharjo et al., 2002)et al., 2002)
NorthNorth--trending high trending high follows ridge axisfollows ridge axis
Circular gravity high near Circular gravity high near TelagaTelaga BodasBodas
22--D D modellingmodelling
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The The KarahaKaraha--TelagaTelaga BodasBodasGeothermal System, Indonesia Geothermal System, Indonesia ((RaharjoRaharjo et al., 2002)et al., 2002)
The The KarahaKaraha--TelagaTelaga BodasBodasGeothermal System, Indonesia Geothermal System, Indonesia ((RaharjoRaharjo et al., 2002)et al., 2002)
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Repeat SP measurements at the Repeat SP measurements at the SumikawaSumikawa geothermal field, Japan geothermal field, Japan (Matsushima et al., WGC 2000)(Matsushima et al., WGC 2000)
Using surface SP to monitor underground fluid flow Using surface SP to monitor underground fluid flow -- an example from a an example from a HDR stimulation (HDR stimulation (DarnetDarnet et al., EAGE 64th Conference, 2002)et al., EAGE 64th Conference, 2002)
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SP monitoring during the hydraulic fracturing using the TGSP monitoring during the hydraulic fracturing using the TG--2 well 2 well (Kawakami & (Kawakami & TakasugiTakasugi, EAGE 56th Conference, 1994), EAGE 56th Conference, 1994)
Field setField set--up of Fluid Flow up of Fluid Flow Tomography, i.e. SP Tomography, i.e. SP monitoring integrated with monitoring integrated with misemise--àà--lala--massemasse (MAM) (MAM) measurementmeasurement
Reservoir monitoring by a Reservoir monitoring by a 44--D electrical technique D electrical technique (Ushijima et al., The (Ushijima et al., The Leading Edge, vol. 18 no. Leading Edge, vol. 18 no. 12, 1999)12, 1999)
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Hot dry rock (HDR) hydraulic Hot dry rock (HDR) hydraulic fracturing experiment, fracturing experiment, OgachiOgachiElectric Power Industry, Akita Electric Power Industry, Akita PerfecturePerfecture, Japan, Japan