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- Tasks and activities:
- Drilling
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Results 31 - 33 of 33
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1/1/1976 - Reports of InvestigationsThe Bureau of Mines conducted research to determine the effectiveness of long holes drilled in solid virgin coal in degasifying an area of the Pittsburgh coalbed showing that horizontal holes drilled into a virgin coalbed from the bottom of any shaft wi...
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1/1/1975 - Reports of InvestigationsCoal is a soft and brittle material. Drilling rates in the Pittsburgh coalbed using a drag bit exceed 3 ft/min at 2,500-pound thrust. However, maintaining the bit on a horizontal trajectory or parallel to bedding planes to attain lengths of 1,000 feet i...
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3/1/1969 - Technical Progress ReportsThe Bureau of Mines conducted drilling studies in the Pocahontas No. 3, the Pittsburgh, and a western coalbed to establish the gas migration characteristics for each.
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Content source: National Institute for Occupational Safety and Health, Mining Program