Rotary drilling holes in coalbeds for degasification

Details

• Personal Author:
  Aul, George N. ; Cervik, Joseph ; Fields, H. H.
• Corporate Authors:
  United States. Bureau of Mines
• Description:
  "Coal 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 is difficult. This Bureau of Mines report presents a drill string configuration that can be guided through the coalbed. The angle of the borehole is measured periodically and by proper combinations of bit thrust and rotational speed (r/min), bit trajectory can be lifted or dropped to keep the bit in the coalbed. An example of a hole drilled to 2,126 feet is presented to show levels of thrust and rotational speed used to lift or drop the bit, the seemingly unexplainable events that occur, and the strategy used during drilling. Thrust levels during drilling range from 600 to 2,500 pounds. Hydraulic motors powered by a 30-hp, 440-volt motor provide ample power for drilling horizontal holes 2,000 feet long." - NIOSHTIC-2
  
  NIOSHTIC no. 10000710
  
  
• Subjects:
  Coal Coal Mining Engineering Explosions Methane Mining Occupational Health Safety
• Series:
  Mining Publications
• Subseries:
  Report of Investigations
• Document Type:
  Text
• Genre:
  Report
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  21 numbered pages
• NIOSHTIC Number:
  nn:10000710
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:b464190d3e42722e52548cf081e6d8f1d88cc69d736bb3db4b620502f123f370a52c3db4cfe5922bed56b96a4764cb3b78290d447b003701dee0d114c700fd92
• Download URL:
  https://stacks.cdc.gov/view/cdc/9242/cdc_9242_DS1.pdf
• File Type:
  [PDF - 1.69 MB ]