Enhanced bandwidth transducer for well integrity measurement

摘要

A single critically damped acoustic stack yields a wide frequency range as an acoustic transmitter or as an acoustic transducer having particular use in well integrity determination. The critically damped present acoustic stack utilizes a plurality of stacked acoustic elements such as piezoelectric ceramics that are energized in two manners, providing different center frequencies; each producing a respective center frequency of 100% bandwidth to yield an acoustic stack having a total bandwidth exceeding the bandwidth of an acoustic element or the bandwidth of the plurality of acoustic elements. One manner of energizing is to pulse only one of the acoustic elements. The other manner is to pulse a first acoustic element the pulse a second acoustic element after a delay equal to the amount of time it takes for the first pulse to reach the face of the second acoustic element. The acoustic elements are bonded together and onto a critically damped backing of tungsten. The assembly is retained in a housing that is preferably made of PEEK. The acoustic stack is primarily used in pulse-echo analysis of metal casing wall thickness and cement bond quality detection of wells.

主权项

1. An acoustic transmitter comprising:
a housing; a backing disposed in the housing and formed of a material having high acoustic attenuation properties; a first acoustic element disposed in the housing and mounted to the backing; a second acoustic element disposed in the housing and mounted to the first acoustic element; a first positive electrical lead connected to a face of the first acoustic element that is adjacent to the backing; a negative electrical lead connected to a second face of the first acoustic element that is distal to the backing, and to a face of the second acoustic element that is adjacent to the second face of the first acoustic element; and a second positive electrical lead connected to a second face of the second acoustic element that is distal to the face of the second acoustic element; wherein the first and second acoustic elements are connectable to a source to energize the first and second acoustic elements in two manners to provide a bandwidth larger than the bandwidth of the center frequency of either the first or second acoustic element in which only one of the first and second acoustic elements is energized, and in which the first acoustic element is energized then the second acoustic element is energized after energizing the first acoustic element.