Horizontal trajectories of rotary-drilled holes. Report of Investigations/1988
Technical Report
·
OSTI ID:6640649
The 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 (4.9 m) from a target at 1,000 ft (305 m). 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 (305 m).
- Research Organization:
- Bureau of Mines, Pittsburgh, PA (USA). Pittsburgh Research Center
- OSTI ID:
- 6640649
- Report Number(s):
- PB-89-104087/XAB; BM-RI-9177
- Country of Publication:
- United States
- Language:
- English
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