Abstract: An insert apparatus for use in a test formation for a downhole nuclear spectroscopy tool includes an outer liner, and an inner liner defining a cylindrical borehole having a diameter such that the downhole nuclear spectroscopy tool is receivable therein. There is fill material between the outer liner and the inner liner, the material including a formation base material and an elemental standards material. The outer liner, the inner liner, and the fill material are configured such that an elemental standard measurement derived from a test using the insert apparatus is equivalent to an elemental standard measurement from a selected formation.

Abstract: A pressure compensation system for a wellbore instrument coupled to a drill string includes a shaft rotatably mounted with respect to an instrument housing. A lubrication chamber included in the instrument has at least one bearing for rotatably supporting the shaft. The lubrication chamber includes a face seal coupled on one face to the shaft and on another face to the housing. A pressure compensator establishes hydraulic communication between the lubrication chamber and the interior of the drill string. The compensator includes a barrier to fluid movement between the lubrication chamber and the interior of the drill string. The barrier enables pressure communication therebetween. The compensator includes a pressure communication port extending between the barrier and a portion of the shaft exposed to the interior of the drill string.

Abstract: An insert apparatus for use in a test formation for a downhole nuclear spectroscopy tool includes an outer liner, and an inner liner defining a cylindrical borehole having a diameter such that the downhole nuclear spectroscopy tool is receivable therein. There is fill material between the outer liner and the inner liner, the material including a formation base material and an elemental standards material. The outer liner, the inner liner, and the fill material are configured such that an elemental standard measurement derived from a test using the insert apparatus is equivalent to an elemental standard measurement from a selected formation.

Abstract: A pressure compensation system for a wellbore instrument coupled to a drill string includes a shaft rotatably mounted with respect to an instrument housing. A lubrication chamber included in the instrument has at least one bearing for rotatably supporting the shaft. The lubrication chamber includes a face seal coupled on one face to the shaft and on another face to the housing. A pressure compensator establishes hydraulic communication between the lubrication chamber and the interior of the drill string. The compensator includes a barrier to fluid movement between the lubrication chamber and the interior of the drill string. The barrier enables pressure communication therebetween. The compensator includes a pressure communication port extending between the barrier and a portion of the shaft exposed to the interior of the drill string.