广东海洋大学海洋与气象学院 人才引进需求和政策简介€¦ · 学（物理海洋、海洋化学和海洋地质方向）、大气科学（天气动力、海洋气
油ガス田探鉱における海洋電磁法の 適用可能性...3. 海洋電磁法の概要 3.1...
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55 石油・天然ガスレビュー アナリシス 油ガス田探鉱における海洋電磁法の 適用可能性 JOGMEC R&D 推進部 山根 一修 1. はじめに 近年、海底油ガス田の大水深化が急速に進み、メキシ コ湾、西アフリカのアンゴラ沖、ブラジルのカンポスベ イなどでは水深1,500〜2,000mでの石油生産が実用化し つつある。また、水深3,000mを目指した研究開発も盛 んに行われている。こうした背景のもと、海域での探鉱 リスク軽減のための高精度で効率的な探鉱手法の確立が 求められるようになっている。その一つとして、海底で の電磁場観測技術を石油探鉱に適用する試みが2000年以 降、始められ、多くの注目を浴びている。いままで、学 術調査に限られていた海底電磁気観測が石油探鉱に有効 であることが分かるや、OHM（Offshore Hydrocarbon Mapping）社、EMGS（Electromagnetic Geoservices AS）社、AGO（AOA Geomarine Operation）社（現 WesternGeco社）などの海洋電磁法調査会社が、わずか 数年のうちに設立された。 現在、学術調査や石油探鉱で用いられている海洋電磁 法は、主に自然界の電磁場変動を観測するMT法 （Magnetotelluric）と、制御電流源を用いるCSEM法 （Controlled Source ElectroMagnetics）に大別される（図 1）。最近、海洋での電磁法調査に関する文献が、諸外 国の雑誌で見受けられるようになってきた。そこで今回 は、海洋電磁法の簡単な概要のほかに、それらの雑誌で はあまり紹介されていない観測装置などの話題も加えて 当該技術を紹介する。 海洋電磁法の分類 図1 （注）上段：MT法では自然界の電磁場の観測を行う。 （注）下段：CSEM法では人工的に海中で電磁場を発生させる。 出所：Scripps Institution of Oceanography Marine EM Laboratoryホー ムページより 2. JOGMECの電磁法への取り組み JOGMECでは、石油公団当時の1990年代から石油探 鉱を目的にした電磁法の研究を行ってきたが、そのなか でも、北海道、東北地方の日本海側含油第３系を対象と したMT法の調査研究が特筆される。 MT法とは、太陽風や赤道付近で発生した空電現象に 起因する外部磁場擾 じょうらん 乱により、大地にどのような電流が 生じるかを電磁誘導現象に基づいて理解し、大地の比抵 抗構造を推定する調査技術である。MT法は、日本語で は地磁気地電流法と呼ばれていたこともあるが、そもそ も日本で原理が見出され（Rikitake,1950）、その後 Cagniard（1953）によって初期の理論がまとめられた 手法である。自然界に存在する物理現象を信号源として 利用するという点では、一見すると、自然地震などを用 いた地震学のアナロジーが適用できるように見える。し かし、MT法は、さまざまな周波数成分を有する地球外 部の電離圏・磁気圏を起源とする磁場変化が大地に入射 して、大地中を波動としてどのように伝播するかを調べ るのではなく、どのように入射磁場が拡散・減衰してい くかを調べる。 さて、JOGMECのMT法の研究のなかで、高倉他
Transcript of 油ガス田探鉱における海洋電磁法の 適用可能性...3. 海洋電磁法の概要 3.1...
P055-074_.indd1.
MagnetotelluricCSEM Controlled Source ElectroMagnetics 1
MT CSEM Scripps Institution of Oceanography Marine EM Laboratory
562008.3 Vol.42 No.2
3.
3.1
MT MTkm MT
Cox, 1986 CSEM CSEM MT CSEMMT CSEM
57
Martin Sinha 19801990CSEM 1999
DASI CSEMDASI 1,000A SN DASI CSEM 1990 StatoilStatoilHydro CSEMSea Bed LoggingSBL200011 DASI Eidesmo ,2002200111StatoilShell CSEM
2
1980
1984
1985
1988
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1993
19944
199510
199810
200011
20011
20017
200111
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20028
200210
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20036
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tube wave
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10-15V/Am2
ρ f
δ≈503√ fHzρ δ 1e0.37
3.3 CSEM
O 2 PC MMT24 MMT24 PersistorCF1 CPU M M T 2 4 P i c o D o s Motocross A/D/ 24 GMR GPSGPS GPS
5
3 12 kHz
20msec km WesternGeco Edgetech
m -Ag-AgCl 6
m10m MT μV V μV10-
2
61
CSEM Schlumberger-EMIMT cm1.3m Schlumberger-EMI
http://marineemlab.ucsd.edu/
3.3.3 CSEMMT 6 m
5
http://marineemlab.ucsd.edu/
SUESI
CSEM
CSEM8
(FFT
duty CSEM CSEM × yaw 10 1,500m/s±% CSEM S/N
CSEM MT MTCSEM
4.2
9
JOGMEC
-20,000 -10,000 0 10,000 20,000
-20,000 10,000 0 10,000 20,000
/ ^ /^
1E-4 1E-5
ill-posed
10
/
2.5 CSEMMT 2.5 CSEM 122.5km 1.0Ωm25m30Ωm 2.5km km 15Ωm 0.1Hz 0.3Hz 1.5km
2000, Mitsuhata2002 2.5
CSEM CSEM10
Smith1996Newman and Alumbaugh1995
Sugeng ,1999 Zhdanov
12
0.0 - - - - - -
D ep th (m )
D ep th (m )
D ep th (m )
D ep th (m )
D ep th (m )
0.3 1.0 3.0 10.0 20.0 Resistivity
67
WEB 13EMGS CSEM
5. CSEM
http://www.emgs.com/_assets/media/files/46-36lores.pdf
http://www.ohmsurveys.com/dataanalysis17.php
Srnka2005
24 .25Hz 70Ωm0.52.0Ωm
4EMGS16
Amundsen2004http://www.emgs.com/_assets/documents/0511_o-g_journal.pdf
6.2 EMGSElectromagnetic Geoservices
6.
xy EMGS xy Siemens
6.3 O H M O f f s h o r e H y d r o c a r b o n
Mapping
air waveOHM2004 air wave 12120m
6.4 PGSPetroleum Gas Services
PGS2007 MTEM MTEM2004 MTEMMulticomponent Transient EMCSEM Ziolkowski
CSEM
OHM
CSEM 1 23
(1)
(2)
7.
(3)
CSEM CSEM CSEM
CSEM air wave air waveair wave air wave air wave 17100m semi-log 0.3ΩmΩm
0.3Hz air wave
8. CSEM
JOGMEC
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722008.3 Vol.42 No.2
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Aki, K., and Richards, P., 1980, Quantitative seismology Theory and Method, W. H. Freeman and Company, 695-717. Amundsen, H. E.F., Johansen, S., and Rosten, T., 2004, A Sea Bed Logging (SBL) calibration survey over the Troll gas fi eld, 66th EAGE Conference & Exhibition. Badea, E.A., Everett, M.E., Newman, G.A., and Biro, O., 2001, Finite-element analysis of controlled-source electromagnetic induction using Coulomb-gauged potentials: Geophysics, 66, 786-799. Cagniard, L., 1953, Basic theory of the magnetotelluric method of geophysical prospecting, Geophysics, 18, 605-635. Chave, A., and Cox, C, S., 1982, Controlled electromagnetic sources for measuring electrical conductivity beneath the oceans, Journal of Geophysics, 87, 5327-5338. Chave, A., Constable, S., and Edwards, N, 1991, Electromagnetic Methods in Applied Geophysics, Vol.2, Chapter 12: Soc. Expl. Geophysics. Constable, S., A. Orange, G.M. Hoversten, and H.F. Morrison, 1998, Marine magnetotellurics for petroleum exploration Part 1. A seafl oor instrument system, Geophysics, 63, pp. 816-825. Cox, C.S., Constable,S., Chave, A.D., and Webb, S., 1986, Controlled source electromagnetic sounding of the oceanic lithosphere, Nature, 320, 52-54. Eidesmo, T., Ellingsrud, S., Macgregor, L. M., Constable., Sinha, M. C., Johansen, S. E., Kong, F. N., and Westerdahl, M. 2002, Sea Bed Logging (SBL), a new method for remote and direct identifi cation of hydrocarbon fi lled layers in deepwater areas, First Break, 20, March, 144-152. Key, K. W., 2003, Application of broadband marine magnetotelluric exploration to a 3D salt structure and a fast-spreading ridge, Ph. D. Thesis, University of California, San Diego. Filloux, J. H., 1977, Ocean-fl oor magnetotelluric sounding over North Central Pacfi c, Nature, 269, 297-301. Mitsuhata, Y., 2000, 2-D electromagnetic modeling by finite-element method with a dipole source and topography: Geophysics, 65, 465-475. Mitsuhata, Y., Uchida, T. and Amano, H., 2002, 2.5-D inversion of frequency-domain electromagnetic data
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198919982000 2007711JOGMEC
generated by a grounded-wire source: Geophysics, 67, 1753-1768. Newman, G.A., and Alumbaugh, D.L., 1995, Frequency-domain modeling of airborne electromagnetic responses using staggered finite differences: Geophys. Prosp., 43, 1021-1042. Rikitake, R., 1950, Electromagnetic induction within the earth and its relation to the electrical state of the earth’s interior, Bull. Earthq. Res. Inst., 28. Srnka, L. J., Carazzone, J.J., and Willen, D. E., 2005, Remote Reservoir Resistivity Mapping – Breakthrough Geophysics for the Upstream, Offshore Technology Conference. Smith, J.T., 1996, Conservative modeling of 3-D electromagnetic fields: Geophysics, 61, 1308-1324. Sugeng, F., Raiche, A., and Rijo, L., 1993, Comparing the time-domain EM response of 2D and elongated 3D conductors excited by rectangular loop source: J. Geomag. Geoelectr., 45, 873-875. Sugeng, F., Raiche, A., and Xiong, Z., 1999, An edge-element approach to modeling the 3D EM response of complex structures with high contrasts: The Second International Symposium on Three-Dimensional Electromagentics (3DEM-2), University of Utah, Salt Lake City, October 26-29. , , ,1994, MT , , 47, 24-35. , , , 1995, MT, , 48, 356-371. , , , , 1997, MT , , 62, 59-68. Ward, S. H., and Hohmann, G. W., 1988, Electromagnetic theory for geophysical applications, in Nabighian, M.N., ed., Electromagnetic methods in applied geophysics – Theory: Soc. Expl. Geophysics. Wright, A., Ziolkowski, A., and Hobbs, B., 2002, Hydrocarbon detection and monitoring with a multicomponent transient electromagnetic (MTEM) survey, The Leading Edge, 21, 852-864.
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MagnetotelluricCSEM Controlled Source ElectroMagnetics 1
MT CSEM Scripps Institution of Oceanography Marine EM Laboratory
562008.3 Vol.42 No.2
3.
3.1
MT MTkm MT
Cox, 1986 CSEM CSEM MT CSEMMT CSEM
57
Martin Sinha 19801990CSEM 1999
DASI CSEMDASI 1,000A SN DASI CSEM 1990 StatoilStatoilHydro CSEMSea Bed LoggingSBL200011 DASI Eidesmo ,2002200111StatoilShell CSEM
2
1980
1984
1985
1988
1989
1993
19944
199510
199810
200011
20011
20017
200111
20021
20022
20026
20028
200210
200211
20036
20042
200412
tube wave
0 2,000 4,000 6,000 8,000 10,000 12,000
10
10
10
10
10
10
10
10
10
10
-7
-8
-9
-10
-11
-12
-13
-14
-15
-16
10-15V/Am2
ρ f
δ≈503√ fHzρ δ 1e0.37
3.3 CSEM
O 2 PC MMT24 MMT24 PersistorCF1 CPU M M T 2 4 P i c o D o s Motocross A/D/ 24 GMR GPSGPS GPS
5
3 12 kHz
20msec km WesternGeco Edgetech
m -Ag-AgCl 6
m10m MT μV V μV10-
2
61
CSEM Schlumberger-EMIMT cm1.3m Schlumberger-EMI
http://marineemlab.ucsd.edu/
3.3.3 CSEMMT 6 m
5
http://marineemlab.ucsd.edu/
SUESI
CSEM
CSEM8
(FFT
duty CSEM CSEM × yaw 10 1,500m/s±% CSEM S/N
CSEM MT MTCSEM
4.2
9
JOGMEC
-20,000 -10,000 0 10,000 20,000
-20,000 10,000 0 10,000 20,000
/ ^ /^
1E-4 1E-5
ill-posed
10
/
2.5 CSEMMT 2.5 CSEM 122.5km 1.0Ωm25m30Ωm 2.5km km 15Ωm 0.1Hz 0.3Hz 1.5km
2000, Mitsuhata2002 2.5
CSEM CSEM10
Smith1996Newman and Alumbaugh1995
Sugeng ,1999 Zhdanov
12
0.0 - - - - - -
D ep th (m )
D ep th (m )
D ep th (m )
D ep th (m )
D ep th (m )
0.3 1.0 3.0 10.0 20.0 Resistivity
67
WEB 13EMGS CSEM
5. CSEM
http://www.emgs.com/_assets/media/files/46-36lores.pdf
http://www.ohmsurveys.com/dataanalysis17.php
Srnka2005
24 .25Hz 70Ωm0.52.0Ωm
4EMGS16
Amundsen2004http://www.emgs.com/_assets/documents/0511_o-g_journal.pdf
6.2 EMGSElectromagnetic Geoservices
6.
xy EMGS xy Siemens
6.3 O H M O f f s h o r e H y d r o c a r b o n
Mapping
air waveOHM2004 air wave 12120m
6.4 PGSPetroleum Gas Services
PGS2007 MTEM MTEM2004 MTEMMulticomponent Transient EMCSEM Ziolkowski
CSEM
OHM
CSEM 1 23
(1)
(2)
7.
(3)
CSEM CSEM CSEM
CSEM air wave air waveair wave air wave air wave 17100m semi-log 0.3ΩmΩm
0.3Hz air wave
8. CSEM
JOGMEC
0 2,500 5,000 7,500 10,000 12,500 15,000
0 2,500 5,000 7,500 10,000 12,500 15,000
1,000
800
600
400
200
0
1,500 1,000 500 200 100
1,500 1,000 500 200 100
0 2,500 5,000 7,500 10,000 12,500 15,000
0 2,500 5,000 7,500 10,000 12,500 15,000
1,000
800
600
400
200
0
1,500 1,000 500 200 100
1,500 1,000 500 200 100
722008.3 Vol.42 No.2
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Aki, K., and Richards, P., 1980, Quantitative seismology Theory and Method, W. H. Freeman and Company, 695-717. Amundsen, H. E.F., Johansen, S., and Rosten, T., 2004, A Sea Bed Logging (SBL) calibration survey over the Troll gas fi eld, 66th EAGE Conference & Exhibition. Badea, E.A., Everett, M.E., Newman, G.A., and Biro, O., 2001, Finite-element analysis of controlled-source electromagnetic induction using Coulomb-gauged potentials: Geophysics, 66, 786-799. Cagniard, L., 1953, Basic theory of the magnetotelluric method of geophysical prospecting, Geophysics, 18, 605-635. Chave, A., and Cox, C, S., 1982, Controlled electromagnetic sources for measuring electrical conductivity beneath the oceans, Journal of Geophysics, 87, 5327-5338. Chave, A., Constable, S., and Edwards, N, 1991, Electromagnetic Methods in Applied Geophysics, Vol.2, Chapter 12: Soc. Expl. Geophysics. Constable, S., A. Orange, G.M. Hoversten, and H.F. Morrison, 1998, Marine magnetotellurics for petroleum exploration Part 1. A seafl oor instrument system, Geophysics, 63, pp. 816-825. Cox, C.S., Constable,S., Chave, A.D., and Webb, S., 1986, Controlled source electromagnetic sounding of the oceanic lithosphere, Nature, 320, 52-54. Eidesmo, T., Ellingsrud, S., Macgregor, L. M., Constable., Sinha, M. C., Johansen, S. E., Kong, F. N., and Westerdahl, M. 2002, Sea Bed Logging (SBL), a new method for remote and direct identifi cation of hydrocarbon fi lled layers in deepwater areas, First Break, 20, March, 144-152. Key, K. W., 2003, Application of broadband marine magnetotelluric exploration to a 3D salt structure and a fast-spreading ridge, Ph. D. Thesis, University of California, San Diego. Filloux, J. H., 1977, Ocean-fl oor magnetotelluric sounding over North Central Pacfi c, Nature, 269, 297-301. Mitsuhata, Y., 2000, 2-D electromagnetic modeling by finite-element method with a dipole source and topography: Geophysics, 65, 465-475. Mitsuhata, Y., Uchida, T. and Amano, H., 2002, 2.5-D inversion of frequency-domain electromagnetic data
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2
3
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8
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10
198919982000 2007711JOGMEC
generated by a grounded-wire source: Geophysics, 67, 1753-1768. Newman, G.A., and Alumbaugh, D.L., 1995, Frequency-domain modeling of airborne electromagnetic responses using staggered finite differences: Geophys. Prosp., 43, 1021-1042. Rikitake, R., 1950, Electromagnetic induction within the earth and its relation to the electrical state of the earth’s interior, Bull. Earthq. Res. Inst., 28. Srnka, L. J., Carazzone, J.J., and Willen, D. E., 2005, Remote Reservoir Resistivity Mapping – Breakthrough Geophysics for the Upstream, Offshore Technology Conference. Smith, J.T., 1996, Conservative modeling of 3-D electromagnetic fields: Geophysics, 61, 1308-1324. Sugeng, F., Raiche, A., and Rijo, L., 1993, Comparing the time-domain EM response of 2D and elongated 3D conductors excited by rectangular loop source: J. Geomag. Geoelectr., 45, 873-875. Sugeng, F., Raiche, A., and Xiong, Z., 1999, An edge-element approach to modeling the 3D EM response of complex structures with high contrasts: The Second International Symposium on Three-Dimensional Electromagentics (3DEM-2), University of Utah, Salt Lake City, October 26-29. , , ,1994, MT , , 47, 24-35. , , , 1995, MT, , 48, 356-371. , , , , 1997, MT , , 62, 59-68. Ward, S. H., and Hohmann, G. W., 1988, Electromagnetic theory for geophysical applications, in Nabighian, M.N., ed., Electromagnetic methods in applied geophysics – Theory: Soc. Expl. Geophysics. Wright, A., Ziolkowski, A., and Hobbs, B., 2002, Hydrocarbon detection and monitoring with a multicomponent transient electromagnetic (MTEM) survey, The Leading Edge, 21, 852-864.
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