Results 31 - 39 of 39

• Longwall Gob Degasification With Surface Ventilation Boreholes Above the Lower Kittanning Coalbed
  1/1/1976 - Reports of Investigations
  Methane emission from two surface gob-degasification boreholes was measured by the Bureau of Mines. The investigation took place during mining of a 3,200-foot longwall panel in the Lower Kittanning coalbed in central Pennsylvania. The first hole was 500...
• Commercial-Quality Gas From a Multipurpose Borehole Located in the Pittsburgh Coalbed
  1/1/1975 - Reports of Investigations
  This report describes a multipurpose borehole used for both degasification and the production of commercial-quality gas. The multipurpose borehole was drilled into a barrier pillar, and seven horizontal degasification holes and one pressure point hole w...
• Rotary Drilling Holes in Coalbeds for Degasification
  1/1/1975 - Reports of Investigations
  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 i...
• Two-Phase Flow in Coalbeds
  1/1/1975 - Reports of Investigations
  This report reviews experimental evidence indicating a relative permeability effect that causes the flow of methane to increase with time when a coalbed is degassed by boreholes.
• Hydraulic Stimulation Increases Degasification Rate of Coalbeds
  1/1/1975 - Reports of Investigations
  Coal degasification boreholes drilled from the surface have been successfully hydraulically stimulated to increase the flow of gas from the coal. This Bureau of Mines report describes the hydraulic stimulation procedure for a coalbed, the equipment requ...
• Effect of a Surface Borehole on Longwall Gob Degasification (Pocahontas No. 3 Coalbed)
  1/1/1972 - Reports of Investigations
  The use of a partially slotted 6.5-Inch-inside-diameter vertical pipe to remove methane from a longwall gob area at a depth of 2,260 feet in the Pocahontas No. 3 Coalbed was investigated. The value of gas removed by such a pipe under free-flow condition...
• Behavior of Coal-Gas Reservoirs
  5/1/1969 - Technical Progress Reports
  Gas occurs in coalbeds in an adsorbed and a free gas state. Adsorbed gas is stored in the micropore structure and its transport is governed by Fick's law. The free gas occurs in the fracture system and flows according to Darcy's law. These two modes of ...
• Use of Vertical Boreholes for Assisting Ventilation of Longwall Gob Areas
  3/1/1969 - Technical Progress Reports
  An experimental degasification program using a vertical borehole and vacuum pump to drain gas from the gob area of a longwall panel was successful at Bethlehem Mines Corporation, Cambria Division, No. 33 coal mine. Sixty-one million cubic feet of methan...
• Removing Methane (Degasification) from the Pocahontas No. 4 Coalbed in Southern West Virginia
  1/1/1963 - Reports of Investigations
  Tests were conducted in the Pocahontas No. 4 coalbed in southern West Virginia to determine if successful degasification techniques, developed during an earlier study in the Pittsburgh coalbed, would effectively remove methane from those usually more ga...