Horizontal trajectories of rotary-drilled holes

Technical Report · Fri Jan 01 04:00:00 EST 1988

OSTI ID:6836247

Goodman, T W; Cervik, J

This Bureau of Mines report investigates the horizontal trajectory of boreholes drilled in coalbeds using the rotary drilling technique. Test holes drilled in coalbeds showed that the path of a borehole in the horizontal plane depends on drilling assembly configuration, drill bit rotation, and coalbed geologic features. An assembly that contained an 18-ft (5.5-m) long drill collar and two centralizers had the best horizontal stability evidenced by trajectories that deviated less than 16 ft. (4.9m) from a target at 1,000 ft (305m). Removal of one of the centralizers resulted in a loss of control of hole trajectory in the horizontal plane. Generally, holes tended to turn to the right, presumably because of right-hand rotation of the bit. Deviations from the original bearing line were as much as 200 ft (61 m) or more at a depth of 1,000 ft (305m).

• Research Organization: Bureau of Mines, Pittsburgh, PA (USA)
• OSTI ID: 6836247
• Report Number(s): RI-9177
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
012010* -- Coal
Lignite
& Peat-- Mining-- Planning & Surveying-- (1987-)
BOREHOLES
CAVITIES
COAL DEPOSITS
COAL SEAMS
DEPTH
DIMENSIONS
DIRECTIONAL DRILLING
DRILL BITS
DRILLING
DRILLING EQUIPMENT
EQUIPMENT
ERRORS
GEOLOGIC DEPOSITS
GEOLOGY
MINERAL RESOURCES
NATIONAL ORGANIZATIONS
RESOURCES
ROTARY DRILLING
TECHNOLOGY ASSESSMENT
TRAJECTORIES
US BUREAU OF MINES
US DOI
US ORGANIZATIONS