| 講演要旨(和文) | | 音波検層波形データを利用して高分解能な減衰特性を導出する方法論は近年その有効性が示されてきている。本研究では、これまで有効性が示されてきたMMFS(modified median frequency shift)法の分解能とSN比を向上させる手法を提案する。音波検層におけるデータ取得方法は、反射法地震探査においてCMP点を形成する点で類似しており、MMFS法を適用する際にCMP的アプローチ発想を導入することによりデータ加算効果を狙うことができる。また、地震波インターフェロメトリを適用することにより、発振器と受振器の間隔を短縮することが可能となり分解能向上を期待することができる。また、SN比と分解能のトレードオフ関係を調整する方法についても提案する。提案手法を数値実験データならびに実フィールド音波検層波形データに適用し、その有効性を示す。 |
|
|
| | 講演要旨(英文) | | Recent attenuation measurements from sonic waveforms have proven the effectiveness in investigating the detailed correlation between the observed high-resolution sonic attenuation estimates and physical properties in a target zone. In the present paper, to further improve the performance of the MMFS (modified median frequency shift) method, we proposed an attenuation estimation method for sonic waveforms by combining CMP approach and SI. The proposed methods were applied to synthetic and field sonic waveforms acquired in carbonate rocks to examine and compare the applicability of the proposed methods with that of the conventional MMFS method both in depth resolution and stability of attenuation results. The proposed methods provide higher depth resolution attenuation estimates in comparison with the MMFS method because the transmitter-receiver distance controlling the depth resolution can be shortened by SI. Our numerical experiments also find the trade-off between the resolution and accuracy of attenuation estimates and imply the optimum selection of receiver pairs used for more stable attenuation analysis. Finally, by preliminarily applying the proposed methods to field sonic data, we demonstrate the advantages of the proposed method in the resolution of attenuation estimates and these observations correlate with those of numerical tests. |
|
|
|
| |
|