GAS FLOW AROUND A BOREHOLE IN A COAL BED AND ITS APPROXIMATE EXPRESSIONS - 1. THE CASE OF A BOREHOLE WITHIN A BOUNDED CIRCULAR AREA.

THIS PAPER PRESENTS AN EASY METHOD FOR CALCULATING BOTH THEAPPROXIMATE DISTRIBUTION OF GAS PRESSURE AND THE GAS FLOW RATE THROUGH A BOREHOLE WITH A BOUNDED CIRCULAR AREA UNDER CONSIDERATION OF ABSORBED GAS. IT WAS FOUND THAT THE GAS DRAINAGE PERIOD IS LONGER IF ABSORBED GAS WAS TAKEN INTO ACCOUNT AND A LARGER BOREHOLE CANNOT SHORTEN THE PERIOD SO MUCH. THESHORTENING OF BOREHOLES INTERVAL IS MORE EFFECTIVE FOR THE PURPOSE. IN JAPANESE WITH ENGLISH ABSTRACT.