Skip to main content
U.S. Department of Energy
Office of Scientific and Technical Information

Bi-center bits for drilling and underreaming moving salt

Conference ·
OSTI ID:7076133
This paper describes the design and use of a bicenter bit while drilling/underreaming a moving salt zone. The bit was based on the end of a 16 in. underreamer to drill an 11-3/8 in. pilot hole. When rotation was stopped, the bi-center design allowed the bit to gauge only 10-5/8 in., eliminating all pilot hole drag. Consequently, drilling/underreaming a thick, fast moving salt zone was accomplished efficiently without any indication of getting stuck in the pilot hole. Fast moving salt formations require special drilling techniques. Recently, a method for drilling and underreaming at the same time was developed. Although successful, the original method required clearing the bit from the pilot hole after drilling only six inches or being on bottom for six minutes. This was necessary to insure that the salt had not moved in far enough to stick the bit in the pilot hole. Even with this ''six-inch or six-minute'' limit, pilot hole drag always ranged between 10,000 lbs and 100,000 lbs with a constant potential of becoming stuck. Additionally, this method resulted in lengthy drilling times through the salt. The bi-center bit described herein, substantially improved drillin/underreaming: pilot hole drag was eliminated, bit sticking was non-existent and conventional ''drilling ahead'' was possible without clearing the pilot hole.
OSTI ID:
7076133
Report Number(s):
CONF-861080-
Country of Publication:
United States
Language:
English

Similar Records

Jet leaching tool accurately underreams salt sections
Journal Article · Sun Feb 05 23:00:00 EST 1995 · Oil and Gas Journal; (United States) · OSTI ID:6634983

A method for drilling moving salt formations - Drilling and underreaming concurrently
Journal Article · Fri Aug 01 00:00:00 EDT 1986 · SPE (Society of Petroleum Engineers) Drill. Eng.; (United States) · OSTI ID:5302720

Application of bicenter bits in well-deepening operations
Journal Article · Sat Jun 01 00:00:00 EDT 1991 · SPE (Society of Petroleum Engineers) Drilling Engineering; (United States) · OSTI ID:5676444