Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Figures Only Full Text Full Text (PDF) Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Rodríguez, R. Articles by Rodríguez, H. R. Search for Related Content GeoRef GeoRef Citation

Applying the mise-à-la-masse method to coal mining problems

GECOH Exploration Inc., Lexington, Kentucky, U.S.

Corresponding author: fax 1-606-258-9139

The first 20% of the full text of this article appears below.

In the United States, coal companies are required by law to leave behind safety barriers (coal block at least 300 ft thick) separating the old mine works from current operations or a coal outcrop because of the potential of huge unexpected inflows of methane gas and water or blowouts. However, this can be difficult when the old mine works, usually belonging to another company, were inaccurately mapped and/or poorly documented. When reliable surveying is in doubt, a company's normal response will be expensive surface drilling to verify the old mine works shown on their maps. Drilling also will have a degree of uncertainty because it provides only one-dimensional data and not a two-dimensional plan view.

Mise-à-la-masse (MALM) can assist the drilling program in finding the estimated boundaries of old flooded mine workings and also can be used as a reconnaissance tool or for determining coal barrier thicknesses, structural and depositional pinchouts, and mapping coal continuity. The energy source and electrode spacing can be adjusted to meet requirements regarding resolution and target depths.

	The method

 
An external electrical current is directly introduced to the coal seam, producing an electric field that travels cylindrically in all directions along the seam. The focusing effect results from the fact that coal is at least an order of magnitude more conductive than roof and floor rocks (e.g., shales, limestones, or sandstones). This is further enhanced when the old mine works are flooded, making the media even more conductive and the application of this method more feasible.

MALM uses a four-electrode system and pole-dipole arrangement. One current electrode is set directly in the coal outcrop (C1) and the second (C2) at the far field to mimic a pole point source. The electric field generated in the coal seam can be mapped . . . [Full Text of this Article]