Imaging a defect in layered media with different shaped interfaces using reverse time migration without velocity...

Area of Science:

• Geophysics
• Acoustic Imaging
• Non-destructive Testing

Background:

• Accurate defect detection in layered media is crucial for structural integrity assessment.
• Conventional methods often require prior knowledge of interface geometry and acoustic velocity, limiting their applicability.

Purpose of the Study:

• To develop and validate a Reverse Time Migration (RTM) based method for defect imaging in layered media without requiring a priori information.
• To accurately reconstruct the interface geometry and determine the acoustic velocity of the lower medium.

Main Methods:

• Utilizing RTM to obtain a high-resolution image of defects.
• Reconstructing the interface geometry from the RTM image.
• Determining the acoustic velocity of the lower medium by minimizing the variance of defect position distribution from scattered echoes.
• Reconstructing the velocity model and performing RTM for defect imaging.

Main Results:

• The proposed RTM method successfully imaged defects in layered media with horizontal, tilted, and circular arc interfaces.
• Reconstructed interface geometry, lower medium acoustic velocity, and defect locations closely matched actual values.
• High accuracy in defect localization and imaging was achieved without prior knowledge of the velocity model.

Conclusions:

• The RTM method provides an effective, data-driven approach for accurate defect characterization in layered media.
• This technique overcomes limitations of traditional methods by eliminating the need for a priori velocity information.
• The validated method holds significant potential for non-destructive evaluation and material characterization.