Geo-Elektromagnetisme(GF-3242)

GeoGeo--EleElekktromagnetistromagnetismeme((GFGF--32423242))

Dr. Hendra GrandisProgram Studi Teknik GeofisikaFakultas Teknik Pertambangan dan Perminyakan –Institut Teknologi Bandung

Dr. Hendra GrandisDr. Hendra GrandisProgram Studi Teknik GeofisikaFakultas Teknik Pertambangan dan Perminyakan –Institut Teknologi Bandung

Tujuan kuliah dan SilabussingkatTujuanTujuan kuliahkuliah dandan SilabusSilabussingkatsingkat

•• MemberikanMemberikan dasardasar--dasardasar konsepkonsep kelistrikankelistrikan dandanelektroelektro--magnetismemagnetisme sertaserta penerapannyapenerapannya padapadametodametoda--metodametoda eksplorasieksplorasi geofisikageofisika

•• SifatSifat kelistrikankelistrikan material material bumibumi, , resistivitasresistivitas, , metodametoda geolistrikgeolistrik, Induced Polarization (IP), , Induced Polarization (IP), SelfSelf--Potential (SP), Potential (SP), magnetotellurikmagnetotellurik (MT), (MT), controlledcontrolled--source audiosource audio--frequency MT (CSAMT), frequency MT (CSAMT), Transient EM (TEM), Very Low Frequency EM Transient EM (TEM), Very Low Frequency EM (VLF(VLF--EM), Ground Probing Radar (GPR) EM), Ground Probing Radar (GPR)

PustakaPustakaPustaka

•• Reynolds, J.M., An Introduction to Applied and Reynolds, J.M., An Introduction to Applied and Environmental Geophysics, Wiley, 1998.Environmental Geophysics, Wiley, 1998.

•• ZhdanovZhdanov, M.S., Keller, G.V., The , M.S., Keller, G.V., The GeoelectricalGeoelectricalMethods in Geophysical Exploration, Elsevier Methods in Geophysical Exploration, Elsevier 1994.1994.

•• BahanBahan pustakapustaka lain (internet: lain (internet: onon--line course, line course, free software free software dlldll.).)

Metode Geo-elektromagnetikMetodMetodee GeoGeo--elektromagnetikelektromagnetik

MetodMetodee perkiraanperkiraan distribusidistribusi sifatsifat fisikafisika bawahbawahpermukaanpermukaan ((resistivitasresistivitas, , ……) ) dengandengan memanfaatkanmemanfaatkanfenomenafenomena / / medanmedan listriklistrik dandan magnetmagnet

•• DC DC resistivityresistivity, Induced Polarization (IP), Self, Induced Polarization (IP), Self--Potential (SP), Applied Potential, Potential (SP), Applied Potential, ……

•• MagnetotelluricsMagnetotellurics (MT), Controlled(MT), Controlled--Source AudioSource Audio--freq. MT (CSAMT), CSEM freq. MT (CSAMT), CSEM ……

•• Transient EM (TEM), Very Low Freq. EM (VLFTransient EM (TEM), Very Low Freq. EM (VLF--EM)EM)

•• Ground Probing Radar (GPR)Ground Probing Radar (GPR)

Aplikasi Metode GEMAplikasiAplikasi MetodeMetode GEMGEM

•• EksplorasiEksplorasi air air tanahtanah, mineral, , mineral, geotermalgeotermal dandanhidrokarbonhidrokarbon

•• StudiStudi lingkunganlingkungan dandan geoteknikgeoteknik ((dispersidispersipencemarpencemar, , identifikasiidentifikasi obyekobyek bawahbawah--tanahtanah, , ronggarongga, , …… ))

•• PemantauanPemantauan prosesproses rere--injeksiinjeksi sumursumurgeotermalgeotermal dandan sumursumur migasmigas (EOR, enhanced (EOR, enhanced oil recovery) oil recovery)

Metode GeolistrikMetodeMetode GeoGeolistriklistrikI

∆V

C1 C2P1 P2

⊕

pengukuranpengukuran responsrespons medium (medium (bumibumi) ) akibatakibatinjeksiinjeksi arusarus searahsearah (DC)(DC)

Metode GeolistrikMetodeMetode GeoGeolistriklistrik

Metode GeolistrikMetodeMetode GeoGeolistriklistrik

ResistivityResistivity Sounding (VES)Sounding (VES)

ResistivityResistivity Tomography Tomography (imaging)(imaging)

AplikasiAplikasi metodametodageolistrikgeolistrik dandan IPIPpadapada eksplorasieksplorasi

mineralmineral

33--DDresistivityresistivity

33--DDInduced Induced

PolarizationPolarization

AplikasiAplikasi metodametoda geolistrikgeolistrik untukuntuk

pengujianpengujian kondisikondisi betonbeton

marine and watercourse marine and watercourse resistivityresistivity surveysurvey

OHMMAPPER OHMMAPPER capacitivelycapacitively--coupled coupled resistivityresistivity meter meter

Induksi ElektromagnetikInduksi ElektromagnetikInduksi Elektromagnetik

medanmedan EM EM yg berubah thd yg berubah thd waktu dari pemancarwaktu dari pemancar (Tx)(Tx)

mengmeng--induinduksiksi arus arus Eddy Eddy padapada material bawah material bawah permukaan permukaan ((kkonduondukktortor) )

arus listrik menghasilkanarus listrik menghasilkanmedan medan magnetimagnetikk sesekukundndeerr

medan EM (listrikmedan EM (listrik dandanmagnetmagnet)) diukur oleh diukur oleh penerima (Rx)penerima (Rx)

Magnetotellurik(MT)MagnetotellurikMagnetotellurik(MT)(MT)

1

10

100

1000

AP

P. R

ES

ISTI

VIT

Y (O

hm.m

)

obs. datacalc. data

0.001 0.01 0.1 1 10 100 1000

PERIOD (sec.)

0

45

90

PH

AS

E (d

eg.)

Magnetotellurik(MT)MagnetotellurikMagnetotellurik(MT)(MT)

data data dandan modelmodel

1 10 100 1000

RESISTIVITY (Ohm.m)

10000

1000

100

DE

PTH

(m)

Magnetotellurik(MT)MagnetotellurikMagnetotellurik(MT)(MT)

data data dandanmodelmodel

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

0 5 10 15 20 25 30 35 40

DISTANCE (x 100m)

0

5

10

15

ELEV

ATI

ON

(x 1

00m

)

Resisitivity (Ohm.m)

5

20

50

200

500

3000

10000

App. Resisitivity (Ohm.m)

0 5 10 15 20 25 30 35 40

1

2

3

4

LOG

FR

EQUE

NCY

(Hz)

10

30

70

200

400

1000

3000

hot-spring hot-spring

Marine MT / CSEMMarine MT / CSEM

VLF-EMVLFVLF--EMEM

Georadar / GPRGeoradarGeoradar / GPR/ GPR

pendugaanpendugaan profilprofil dasardasar danaudanau menggunakanmenggunakan GPRGPR

StudiStudi kebocorankebocoranterowonganterowongan

menggunakanmenggunakan GPRGPR

Frequency Domain EMFrequency Frequency Domain Domain EMEM

GeonicsGeonics EMEM--3131terrain conductivity meterterrain conductivity meter

Frequency Domain EMFrequency Frequency Domain Domain EMEM

GeonicsGeonics EMEM--3434terrain conductivityterrain conductivity--metermeter

Time Domain EMTime Domain Time Domain EMEM

GeonicsGeonics EMEM--6161metal detectormetal detector

Time Domain EMTime Domain Time Domain EMEM GeonicsGeonicsTEM57 transmitterTEM57 transmitterPROTEM receiverPROTEM receiver

Time Domain EMTime Domain Time Domain EMEM PhoenixPhoenix--Geophysics Geophysics TT--4 transmitter4 transmitter

V8 universal receiverV8 universal receiver

Airborne EMAirborne Airborne EMEM

Airborne EMAirborne Airborne EMEM

Experience is not what happens to Experience is not what happens to you. Experience is what you do with you. Experience is what you do with what happens to you.what happens to you.

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