Method and device for acoustic examination of the piping cemented in a borehole.

摘要

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, said pulse stimulating thickness resonance within the walls of the casing. The method according to the invention comprises the steps of : defining 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, defining a second time window corresponding to a second portion of signal S(t) only including the initial reflection from the casing, and determining said casing characteristic from information related to resonance contained in said first time window while normalizing said information by information contained within said second time window.