| 講演要旨(和文) | | 坑井を用いた反射法地震探査では坑井内震源のエネルギーの問題で探査範囲が制限される。そのため震源を地表に設置することが考えられるが、本研究ではKirchhoff の積分定理から解釈される結果を応用して坑井受振データを仮想震源として用いることができることを示し、それにリバースタイムマイグレーションを適用することにより受振データのみから直接地下構造をイメージングする方法を、合成記録を用いた例により紹介する。 |
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| | 講演要旨(英文) | | We apply a novel method to the imaging of well-seismic data. In this approach, we utilize observations as virtual source function.We first derive a presentation from the Kirchhoff integral which suggests us that we can use observations themselves as virtual source function for imaging purpose, and then investigate this suggestion via numerical experiments. Because the virtual source function spreads both over time and space, we adopt the reverse-time migration method. In the reverse-time migration, the spreading source function is naturally incorporated into source wavefield marching and subsurface structure is imaged via cross-correlation between the source wavefield marched forward in time and the receiver wavefield marched backward in time. These aspects are the advantages of the method over the ray theory base ones where the virtual source function is restricted to the point source. In the numerical experiments we attempt to image subsurface structures both for cross-well geometry and VSP geometry. Through these experiments we find the novel method yields correct subsurface images with little artifacts. |
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