海底電磁探査の近年の進歩とメタンハイドレート検出への適用
スポンサーリンク
概要
- 論文の詳細を見る
Marine electromagnetic (EM) sounding methods were developed originally for imaging the deep mantle, partial melt below mid-oceanic ridges, active faults in the crust around subduction zones, etc. Recently, marine EM sounding has been applied extensively for oil, gas, and methane hydrate exploration. In this paper, we introduce various marine EM sounding methods and case studies. Natural fluctuations of EM fields from the ionosphere can be observed on the seafloor using ocean-bottom electromagnetometers (OBEMs), and the marine magnetotelluric sounding method can be applied for imaging the deep structure (> several km below the seafloor). However, the natural signal is less powerful in the higher frequency band and provides less resolution for near-seafloor structures. A high-frequency controlled electromagnetic source on/near/below the seafloor is necessary for evaluating the shallow structure. Marine controlled-source EM (CSEM) sounding using a horizontal electric dipole, towed near the seafloor and sending an electric signal, and OBEMs as receivers settled on the seafloor is widely used for oil and gas exploration, and occasionally for methane hydrate explorations. A vertical electric dipole is also used for magnetometric resistivity (MMR) sounding when exploring hydrothermal systems around ridges. On the other hand, both sources and receivers attached to a cable can be towed near the seafloor for a continuous survey. Towed-CSEM sounding with a time-domain analysis is used especially for methane hydrate exploration. Another type of towed-CSEM with magnetic signal obtains porosity information on near-seafloor sediments. A deep-towed marine DC resistivity survey has been applied near the seafloor, and successfully imaged shallow methane hydrate distributions in sedimentary layers. Thus, various marine EM soundings can illuminate sub-seafloor methane hydrate, and are useful for discussing the accumulation/dissolution process of methane hydrate and the potential of methane hydrate as a new energy resource.
- 社団法人 東京地学協会の論文
- 2009-10-25
著者
-
笠谷 貴史
海洋研究開発機構
-
後藤 忠徳
京都大学大学院工学研究科
-
後藤 忠徳
Jamstec
-
Goto Tada‐nori
Japan Agency For Marine Sci. And Technol.(jamstec) Kanagawa Jpn
-
Goto Tada-nori
Institute For Research On Earth Evolution Japan Agency For Marine Science And Technology (jamstec)
-
Goto Tada-nori
Japan Agency For Marine-earth Science And Technology
-
Goto Tada-nori
Japan Agency Of Marine-earth Science And Technology
-
Goto Tadanori
Department Of Environmental Earth Sciences Aichi University Of Education
-
Goto Tadanori
Research Center For Earthquake Prediction Disaster Prevention Research Institute Kyoto University
-
桜井 紀旭
東京大学大学院新領域創成科学研究科
-
高木 亮
日本海洋掘削株式会社
-
Goto T
Aichi Univ. Education Aichi Jpn
-
笠谷 貴史
海洋研究開発機構 地球内部ダイナミクス領域
関連論文
- 海底電磁探査の近年の進歩とメタンハイドレート検出への適用
- 福島県沖海洋MT法調査とそのインバージョン解析
- Long-Term Monitoring Using Deep Seafloor Boreholes Penetrating the Seismogenic Zone
- 伊豆東方沖地震に誘発された相模湾初島沖の海底地すべり
- 日本海メタンハイドレート地域における海底曳航式電気探査調査
- 四国中央構造線地下構造の総合物理探査
- 研究集会「アスペリティのマッピングとモニタリング (EARS : Exploration of Asperities and Reflectors System)」シンポジウム報告
- 八代海干潟でのVLF-MT探査による湧水検出
- 八代海海底湧水地域でのVLF-MTとSP観測
- 電磁気学的な流体の分布と移動の解明 : 南海トラフを例として