A Logging While Drilling system which has a cavity in its collar wall for holding its instrumentation package

摘要

An LWD system which comprises: a drill collar wall 12 defined by an inner collar surface, and an outer collar surface; and a cavity (13, fig. 2a) in the drill collar wall, which the cavity opens at the outer collar surface. The system has an instrument package 31 that is disposed in the cavity (13, fig. 2a). A source holder cavity is provided in the instrument package. The system has a source 30 of radiation that is affixed to a source holder (132, fig. 4) which is removably mounted within the source holder cavity. The source holder cavity may be lined with an insert 32, whereby the insert is threaded to receive the source holder. The mechanical strength of the threads within the source holder cavity may be improved by the source holder material. The package framework 31 may comprise high Z material 37. The framework may have a pathway 34 in its high Z material 37 that extends radially from the source 30 outward thereby forming a collimator window. This window may be filled with a low Z material. The collimator window may make an acute angle with the major axis of the collar.