Ultrasonic logging methods and apparatus for automatically calibrating measures of acoustic impedance of cement and other materials behind casing
US7755973B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Feb 21, 2008 |
| Grant date | Jul 13, 2010 |
| Priority date | — |
| Expiry date | Feb 21, 2028 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01V1/44
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Methods and apparatus for in situ, continuous, automatic, and real-time acoustic impedance calibration of a transducer in an acoustic logging system. By taking the frequency characteristics of the ultrasonic transducer which are present in the internal casing reflection and convolving them with the frequency characteristics of the casing being logged, a theoretical model is created with a theoretical acoustic impedance fluid producing a theoretical free pipe signal at each measure point. The measured signal is then compared to the theoretical free pipe signal thereby yielding a calibrated acoustic impedance value for at each measure point. The only model employed is in the theoretical calculation of spectrum characteristics of free pipe.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.