Reverse time migration imaging method for cased-hole structure based on ultrasonic pitch-catch measurement

US12345150B2 · kind B2 · utility

Assignee

• University of Electronic Science and Technology of China · CN

Inventors

• Hua Wang · Shanghai, CN
• Meng Li · Taipei, TW

Key dates

• Filing date: Oct 9, 2022
• Grant date: Jul 1, 2025
• Expiry date: Jul 5, 2043

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y02A90/30
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A reverse time migration imaging method for cased-hole based on ultrasonic pitch-catch measurement, including: calculating a theoretical dispersion curve; expanding original Lamb data of two receivers into array waveform data based on phase-shift interpolation; establishing a two-dimensional migration velocity model including density, P-wave velocity and S-wave velocity of a target area; generating and storing a forward propagating ultrasonic wavefield for each time step; reversing a time axis; generating and storing a reversely propagating ultrasonic Lamb wavefield for the two receivers after phase-shift interpolation; calculating envelopes of the forward propagating ultrasonic Lamb wavefield and the reversely propagating ultrasonic Lamb wavefield; applying a zero-lag cross-correlation imaging condition to obtain reverse time migration imaging results; and applying Laplace filtering to suppress low-frequency imaging noises in the imaging results.