Method and apparatus for the acoustic investigation of a casing cemented in a borehole
US5216638A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Apr 20, 1990 |
| Grant date | Jun 1, 1993 |
| Priority date | — |
| Expiry date | Apr 20, 2010 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2291/044
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Method for determining at least one characteristic of a casing cemented in a borehole, such as cement bond and casing thickness, from a reflected acoustic signal S(t) obtained by directing an acoustic pulse at a substantially normal incidence towards a radial sector of the wall of the casing, the pulse stimulating thickness resonance within the walls of the casing. The method according to the invention comprises the steps of: determining a first time window corresponding to a first portion of signal S(t) including the initial reflection from the casing and subsequent acoustic returns due to resonance, determining a second time window corresponding to a second portion of signal S(t) mainly including the initial reflection from the casing, and determining the casing characteristic from information related to resonance contained in the first time window while normalizing the information by information contained within the second time window.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.