LOGGING TOOL WITH A PARASITIC RADIATION SHIELD AND METHOD OF LOGGING WITH SUCH A TOOL

摘要

It is described a logging tool for underground formations surrounding a borehole, comprising an elongated body along a major axis; a collar disposed peripherally around said body having a collar wall defined by an inner and an outer surface; a radiation emitting source arranged to illuminate the earth formation surrounding the borehole; at least one radiation detector arranged to detect radiation reflected by the earth formation resulting from illumination by the source; at least one source collimation -window and one detector collimation window through which the earth formation is illuminated and radiation is detected; and characterized in that it further comprises at least one radiation shield located between said inner collar surface and the outer surface of the tool, said radiation shield positioned so as to eliminate parasitic radiation that has not traversed the outer collar.