APPARATUS AND METHOD FOR MINIMIZING WEAR AND WEAR RELATED MEASUREMENT ERROR IN A LOGGING-WHILE-DRILLING TOOL

摘要

A tool is presented for making density measurements of a formation surrounding a wellbore, comprising a collar housing in a drill string. The housing has at least one first section with a first outer diameter, and at least one sensing section (150) with a second outer diameter (138) located proximate the at least one first section. The second outer diameter is smaller than the first outer diameter. A radioactive source (112) is disposed in the sensing section of the housing. At least two detectors (114, 116) are disposed in the sensing section and spaced from the radioactive source (112) and are positioned to detect radiation resulting from gamma rays emitted by the source.