SONIC LOGGING TOOL INCLUDING RECEIVER AND SPACER STRUCTURE

摘要

A formation logging tool having a substantially continuous central mandrel with regularly spaced mass blocks disposed thereon, at least some of the mas s blocks carrying sensors such as receivers. By adopting this structure, the tool can be made to behave as a mass-spring structure and its flexural and extensional behaviour controlled such that its dispersion curve does not extend into the dispersion curve of the formation to be logged. The structur e can be applied to the whole of the logging tool or just to the receiver section and/or any spacer section between the receiver and the transmitter section.