| 講演要旨(和文) | | 微動アレイ探査の石油・天然ガス調査への適用性を調べるために、対象地域の概略構造を広域的かつ簡便に把握できるとする視点（概査法）と坑井データを利用しながら高分解能に構造解釈できるとする視点（精査法）から多面的に検証した。庄内平野における微動アレイ調査の仕様や適用限界、および、コストを検討した結果、重要な探鉱対象である青沢玄武岩相当の構造形態を３次元的に把握することを目的とした稠密微動アレイ調査が提案できた。SPAC法の中間成果である位相速度曲線は、拘束条件がない地点では誤差が生じる。特に、高次モード混入の対応に関して、解析者の意識や判断に左右されており、統一的な方法論の確立が求められる。微動アレイデータを多点の単点微動データとして利用することが可能であり、3成分観測によるV/Hスペクトルは、石油・天然ガス貯留層の直接検知法として発展する可能性が残されている。 |
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| | 講演要旨(英文) | | From the viewpoint of earthquake engineering and civil engineering, the microtremor array survey is considered as a relatively convenient method for S-wave velocity. To investigate the feasibility for the oil and gas prospecting, the microtremor array survey was tested in and around Amarume, Yamagata Prefecture, Japan and its technical applicability was rigorously examined. As a result this method is considered as a cost effective tool which can grasp the long-wavelength structure of target layer. Because the inversion method does not give a unique solution, the analysis involves some interpretation by processors and it may cause an analytical error. The integrated analysis combined with the gravity data is thought as an effective way to decrease such an error and to improve the accuracy of underground structure. Recently several applications of microtremors are reported for the oil and gas prospecting in foreign countries, suggesting significant correlation between Low Frequency (LF) attributes and the distribution of oil and gas reservoir. Our study indicates that their proposed seismic attributes show no clear indication in Amarume oil field so far but there still remains the possibility of V/H spectrum obtained by 3-component observations as a direct hydrocarbon indicator. |
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