Process for recovering methane gas from subterranean coalseams
AssigneeMethane Drainage Ventures
InventorWalter L. Richards
Life of this patent
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Abstract
A process provides for the recovering of methane gas from subterranean coalseams having sloughing, or caving, characteristics. A borehole is drilled in a generally horizontal direction into a subterranean coalseam and as the drilling progresses, a flushable borehole cake is formed on and in the walls of the horizontal borehole. The borehole cake prevents contemporaneously sloughing, or caving, of the boreholes during the drilling operation. A perforated liner may be inserted into the horizontal borehole and the borehole cake is then flushed out in order to allow methane gas present in the coalseam to enter the liner from which it is collected.
Claims27
A process for recovering methane gas from subterranean coal seams having sloughing, or caving, characteristics, said process comprising the steps of:
- drilling a generally horizontal borehole into a subterranean coal seam;
- forming a flushable borehole cake on and in the wall of the horizontal borehole as it is drilled;
- inserting a perforated liner into the horizontal borehole;
- flushing the borehole cake out of the horizontal borehole;
- and
- collecting methane gas from the liner.
A process for recovering methane gas from a subterranean coalseam having sloughing, or caving, characteristics, said process comprising the steps of:
- drilling a generally horizontal borehole into a subterranean coalseam;
- pumping a slurry, comprising mud solids and water, into the horizontal borehole as drilling progresses in order to form a temporary mud cake on the horizontal borehole wall, said temporary mud cake being formed as the mud solids are deposited on the horizontal borehole wall as the water seeps into the horizonal borehole wall;
- inserting a perforated liner into the horizontal borehole;
- flushing the temporary mud cake out of the horizontal borehole;
- collecting methane gas seeping into the liner through the perforations therein.
A process for recovering methane gas from subterranean coalseams having sloughing, or caving, characteristics, said process comprising the steps of:
- drilling a generally horizontal borehole into a subterranean coalseam using a drill pipe;
- pumping a slurry, comprising Bentonite mud solids and water, down the center of the drill pipe as drilling progresses in order to both lubricate the driling and to form a temporary mud cake on and in the horizontal borehole wall, said temporary mud cake being formed and the slurry returns to the horizonal borehole opening through an annulus defined by the drill pipe and the borehole wall, and the water therein seeps into the horizontal borehole wall;
- inserting a perforated liner into the horizontal borehole;
- pumping fluid down the center of the perforated liner in order to flush the temporary mud cake out of the horizontal borehole;
- and
- thereafter;
- conducting methane gas, collected by the perforated liner, to the horizontal borehole opening.
A process for forming a generally horizontal borehole into a subterranean coalseam comprising the steps of:
- drilling a generally horizontal borehole into a subterranean coalseam;
- forming a flushable borehole cake on and in the wall of the horizontal borehole as it is drilled;
- inserting a perforated liner into the borehole for flushing the flushable borehole cake out of the horizontal borehole;
- and
- flushing the flushable borehole cake out of the horizontal borehole after drilling is completed.
Dependencies are inferred from the claim text.