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Horizontal trajectories of rotary-drilled holes.

Authors
Goodman-TW; Cervik-J
Source
Pittsburgh, PA: U.S. Department of the Interior, Bureau of Mines, RI 9177, 1988 Jan; :1-11
NIOSHTIC No.
10006100
Abstract
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. (4.9 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).
Keywords
Surface-mining; Surface-properties; Underground-mining; Mining-industry; Coal-mining; Structural-analysis; Room-and-pillar-mining
Publication Date
19880101
Document Type
IH; Report of Investigations
Fiscal Year
1988
NTIS Accession No.
PB89-104087
NTIS Price
A03
Identifying No.
RI-9177
NIOSH Division
PRC
Source Name
Pittsburgh, PA: U.S. Department of the Interior, Bureau of Mines, RI 9177
State
PA
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