Charles P Borsos

US Patent:

20090133930, May 28, 2009

Filed:

Nov 27, 2007

Appl. No.:

11/945542

Inventors:

Richard E. Thorp - Shanghai, CN
Raju M. Eason - Stafford TX, US
Charles Borsos - Sugar Land TX, US

Assignee:

SCHLUMBERGER TECHNOLOGY CORPORATION - SUGAR LAND TX

International Classification:

E21B 21/08

US Classification:

175 25

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.