Patent ID: 7028806
Filing Date: 2006-04-18
Classification: G01V

Abstract:
1. An apparatus for performing acoustic investigations while drilling a borehole in a subsurface geological formation, comprising: a. a longitudinally extending assembly conveyed in said borehole on a drilling tubular, said assembly and said drilling tubular having a drilling fluid flowing trough a longitudinally extending passage in said assembly and said drilling tubular; b. an acoustic transmitter supported by the assembly, said transmitter generating acoustic signals in the assembly, the borehole and the subsurface formation; c. an acoustic receiver spaced apart from the transmitter and supported by the assembly for receiving said acoustic signals; and d. an attenuator located in the assembly between said acoustic transmitter and said acoustic receiver for attenuating said acoustic signals in the assembly within a predetermined frequency range, wherein said attenuator comprises a tubular element of a composite material having a substantially cylindrical outer surface, said outer surface having a plurality of spaced-apart masses having a predetermined spacing, mass and length firmly attached thereto.