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Drilling a horizontal coalbed methane drainage system from a directional surface borehole.

Authors
Oyler-DC; Diamond-WP
Source
Pittsburgh, PA: U.S. Department of the Interior, Bureau of Mines, RI 8640, 1982 Jan; :1-50
NIOSHTIC No.
10002321
Abstract
Three long horizontal holes were drilled from a directionally drilled surface hole at the Emerald Mine near Waynesburg, Pennsylvania. The purpose was to adapt the technique of directional drilling for use in draining methane from coalbeds. A 504-m (1,652-ft) long, 76-mm (3-in) diameter, circular arc pilot hole was drilled, using a downhole mud motor, to enter the Pittsburgh coalbed at a vertical depth of 350 m (1,000 ft). The hole was reamed to 222 mm (8-3/4 in) and was cased to a measured depth of 486 m (1,595 ft). Three 76-mm (3-in) diameter horizontal drainage holes were then drilled, totaling 2,909 m (9,544 ft) of horizontal hole. Improvements in drilling methods increased the average drilling rate from 20.4 M (67 ft) to 64.9 M (213 ft) per day. The cost of drilling the directional and horizontal holes (using a government-owned drill rig) was $1,169,530, a figure inflated by inexperience and by delays caused by lost-circulation problems and fishing operations. An estimated total drilling cost of $960,000 (including rental of a drill rig) for an improved system, was determined by a detailed cost analysis. Initial gas and water production from November 1979 through May 1980 was low because of caving of the horizontal holes drilled in shale near the bottom of the casing.
Keywords
Mine-gases; Mining-industry; Methanes; Methane-drainage; Methane-control; Explosive-gases; Explosive-atmospheres; Underground-mining; Coal-mining; Control-technology; Engineering-controls
CAS No.
74-82-8
Publication Date
19820101
Document Type
IH; Report of Investigations
Fiscal Year
1982
NTIS Accession No.
NTIS Price
Identifying No.
RI-8640
NIOSH Division
PRC
Source Name
Pittsburgh, PA: U.S. Department of the Interior, Bureau of Mines, RI 8640
State
PA
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