Results 31 - 40 of 67

• Large-Scale Strata Response to Longwall Mining: A Case Study
  1/1/1992 - Reports of Investigations
  This U.S. Bureau of Mines report summarizes a study of large-scale strata response to longwall mining at a western U.S. coal mine. This study utilized surface and subsurface measurements, geologic mapping, in situ stress measurements, and pressure cell...
• Mine Fire Diagnostics Applied to the Carbondale, PA Mine Fire Site
  1/1/1992 - Reports of Investigations
  The U.S. Bureau of Mines applied its mine fire diagnostic method to an abandoned anthracite mine fire site in Carbondale, Lackawanna County, PA.
• In-Mine Test of the Bureau of Mines Preproduction Wireless Survey System
  1/1/1990 - Reports of Investigations
  The Bureau of Mines preproduction wireless survey system (WSS) and its performance during an in-mine test are discussed in this report. The WSS was developed to reduce downhole surveying time in order to increase the efficiency of drilling long horizont...
• Horizontal Trajectories of Rotary-Drilled Holes
  1/1/1988 - Reports of Investigations
  This Bureau of Mines report investigates the horizontal trajectory of boreholes drilled in coalbeds using the rotary drilling technique.
• Effects of Stimulation Treatments on Coalbeds and Surrounding Strata: Evidence from Underground Observations
  1/1/1987 - Reports of Investigations
  Stimulated vertical boreholes are an effective means of removing gas from coalbeds in advance of mining. This Bureau of Mines report examines the coal mine roof damage potential of stimulation treatments. Twenty-two government-sponsored stimulation trea...
• Accurate Directional Borehole Drilling: A Case Study at Navajo Dam, New Mexico
  1/1/1987 - Reports of Investigations
  Describes a project conducted by the Bureau of Mines in which the accurate directional drilling of a borehole was demonstrated with the objective of intercepting a designated target.
• Comparisons Between Cross-Measure Boreholes and Surface Gob Holes
  1/1/1986 - Reports of Investigations
  The Bureau of Mines conducted studies to compare the effectiveness of the cross-measure borehole system with that of surface gob holes on two successively mined retreating longwalls in the Lower Kittanning coalbed. Only the cross-measure system was in o...
• Comparison of Rotary and In-Hole Motor Techniques for Drilling Horizontal Boreholes in Coal
  1/1/1985 - Reports of Investigations
  This Bureau of Mines report describes and compares the procedures, capital investments, and operating costs of rotary and in-hole motor drilling techniques used to drain methane gas from the Pittsburgh coalbed in an underground mine located in southwest...
• Methane Control on Longwalls with Cross-Measure Boreholes (Lower Kittanning Coalbed)
  1/1/1985 - Reports of Investigations
  The cross-measure borehole technique is an effective method of controlling methane liberated by fracturing the roof strata in longwall gobs where overburden is less than 750 ft (229 m). About 71 pct of the methane produced by longwall mining in the Lowe...
• Simulation of Methane Flows in Noncoal Mines
  1/1/1984 - Reports of Investigations
  The Bureau of Mines has successfully tested a method to simulate methane (CH4) flows from face areas through the returns of noncoal mines. This technique involves releasing a small quantity of tracer gas at a working area and sampling for that gas downs...