Determining the impedance of material behind a casing in a borehole
US7689362B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 8, 2005 |
| Grant date | Mar 30, 2010 |
| Priority date | — |
| Expiry date | Sep 8, 2025 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01V1/48
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method for estimating an impedance of a material behind a casing wall in a borehole, the method comprises exciting the casing wall with an acoustic pulse, and measuring by means of a transducer an experimental acoustic waveform (W) reflected from the casing wall. The method further comprises initializing an impedance parameter (Zin), computing an inverse casing response (Rcas−1) as a function of the impedance parameter (Zin) and a casing thickness parameter (Casin), and deconvoluting the experimental acoustic waveform with the inverse casing response to obtain a transducer response (T). An iterative loop is performed, comprising the computing of an inverse casing response and the deconvoluting of the experimental acoustic waveform by varying the impedance parameter until the transducer response becomes compact in the time domain. The estimated impedance (Zcem) is obtained from the impedance parameter when the transducer response is compact.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.