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Results 21 - 30 of 39
1/1/1985 - Reports of InvestigationsThis 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...
1/1/1985 - Reports of InvestigationsThe 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...
1/1/1984 - Reports of InvestigationsMethane-drainage holes must be completely filled by grout before mining to prevent the emission of large quantities of gas during mine-through, which would constitute an explosion hazard. In November 1980, seven horizontal holes at the multipurpose bore...
Probability of Encountering Coalbed Discontinuities During Vertical and Horizontal Borehole Drilling1/1/1982 - Reports of InvestigationsProbabilities of encountering coalbed discontinuities during vertical or horizontal drilling in a specific coalbed can be estimated based on analysis of mined-out areas of the coalbed where the size, shape, orientation, and distribution of discontinuiti...
9/1/1981 - Contract reportsThe purpose of this project was to enhance the Bureau of Mine's Cableless Electronic Survey System use to aid in the drilling of long boreholes in coal as part of the methane drainage program. The system that was ultimately developed was field tested an...
1/1/1980 - Reports of InvestigationsThe use of vertical surface degasification boreholes with bleeder systems and the use of a timbered bleeder system to degasify gob areas were studied by the Bureau of Mines. This report describes three gob degasification studies conducted in the Pittsbu...
9/1/1978 - Contract reportsThis report describes the feasibility test of an electromagnetic method for locating boreholes, with or without casing, that have been drilled in conjunction with mining operations but without precisely known locations with respect to the tunnel.
1/1/1978 - Reports of InvestigationsThe Bureau of Mines has developed hardware for electromagnetic (EM) detection and location of miners trapped in underground coal mines. This report describes a technique for using the developed equipment for locating uncased boreholes underground.
1/1/1978 - Reports of InvestigationsThe Bureau of Mines examined the wellbore of a vertical gas drainage well in the Mary Lee coalbed to determine the results of specific completion procedures in coal. A jet-slotting tool was used to cut four vertical slots through the casing about 1 ft b...
1/1/1977 - Reports of InvestigationsThe Bureau of Mines evaluated the hydraulic stimulation of a gob degasification borehole to determine if this procedure would aid in degasifying a longwall panel.