DRILL PIPE/CASING PROTECTOR

摘要

A drill pipe/casing protector is mounted on a drill pipe that rotates within a well bore or a casing cemented in a well bore in which drilling operations are conducted. The drill pipe/casing protector comprises a protective sleeve preferably made from a compressible material secured to the exterior of the drill pipe to rotate with the drill pipe during normal drilling operations and to contact the casing and thereby prevent damaging contact between the drill pipe and the casing. The sleeve rotates with the drill pipe during normal drilling operations in which there is an absence of contact between the sleeve and the casing, but the sleeve stops rotating or rotates very slowly while allowing the drill pipe to continue rotating within the sleeve, upon frictional contact between the sleeve and casing. One or more thrust bearings rigidly affixed to the drill pipe maintain the sleeve in a fixed axial position on the drill pipe during contact between the sleeve and the casing. The relative rotation between the sleeve and drill pipe during contact reduces torque on the rotary drill pipe compared with a conventional protector rigidly affixed to and rotatable with the drill pipe. The sleeve includes spaced apart longitudinal grooves and wedged I.D. faces between the grooves for circulating drilling fluid through the space between the sleeve and rotary drill pipe for maintaining a fluid film in the space to reduce frictional drag between the rotating drill pipe and the sleeve when the sleeve stops rotating. The thrust bearings likewise to reduce induced torque by pumping fluid through a series of ramps and slots to lubricate and support the sleeve.