Spiral Drill Collar
The spiral drill collar, invented
and developed by Fred K. Fox in 1961, prevents or mitigates the
problem of differential pressure wall sticking of drill collars
leading to stuck drill strings, a prevalent problem encountered in
drilling deep, high pressure and deviated wells.
Grooves spiraled around the outer
surface of the collar interrupt contact of the collar with the wall
of the bore hole. In subsequent years, the spiral concept has been
expanded to casing, liners, wash pipe, and heavy weight drillpipe.
Spiral collars are used worldwide to this day in virtually all
moderate to deep offshore and onshore wells and in all deviated and
pioneering efforts of the following individuals and companies who
contributed to the development of this technology:
Fred K. Fox