ACOUSTIC ISOLATOR FOR DOWNHOLE APPLICATIONS

摘要

A plurality of heavy mass irregularities (54, 56, 58) attached to an inner wall (60) of the drill collar (52) attenuate waves traveling through the collar. The plurality of heavy mass irregulariti es (54, 56, 58) are spaced and sized for the maximum attenuation of acoustic pulses in a predetermined frequency range. The mass irregularities may be rings secured to the inner surface (60) of the collar by neck pieces (62), extending outwardly from the outer circumference of the ring. The mass irregularities may be made of steel or tungsten and are between six and ten in number. The spacing of the irregularities may lie between twelve and fourteen centimeters. A center pipe (64) may be included to isolate the irregularities from the fluid flow associated with the drilling operation. The pipe may be of a soft material such as rubber to reduce transfer of acoustic noise along the drill string.