	US 7,516,784 B2
	In-situ method of coal gasification
James Q. Maguire, 1515 W. Main, Norman, Okla. 73069 (US)
Filed on Sep. 04, 2007, as Appl. No. 11/849,842.
Application 11/849842 is a continuation of application No. 11/445356, filed on Jun. 01, 2006, granted, now 7,264,049.
Application 11/445356 is a continuation in part of application No. 11/074150, filed on Mar. 07, 2005, granted, now 7,198,107.
Claims priority of provisional application 60/571183, filed on May 14, 2004.
Prior Publication US 2007/0295503 A1, Dec. 27, 2007
This patent is subject to a terminal disclaimer.
Int. Cl. E21B 43/30 (2006.01)

U.S. Cl. 166—245

11 Claims

1. A method for enhancing in-situ coal gasification of subterranean coal by providing a network of fractures in a subterranean formation containing seams of coal, the method comprising the steps of:

providing a substantially vertically disposed borehole;

providing a plurality of substantially horizontally disposed boreholes in fluid communication with the substantially vertically disposed borehole, wherein at least one substantially horizontally disposed borehole is a fracturing borehole, at least one substantially horizontally disposed borehole is an injection borehole and at least one substantially horizontally disposed borehole is a production borehole;

selectively preventing fluid communication between the substantially vertically disposed borehole and the at least one substantially horizontally disposed injection borehole and the at least one substantially horizontally disposed production borehole;

introducing an initial quantity of liquified gas into the at least one substantially horizontally disposed fracturing borehole such that the liquified gas communicates with the subterranean formation;

permitting the quantity of liquified gas to vaporize in a portion of the at least one substantially horizontally disposed fracturing borehole whereby a resulting increase in pressure in the at least one substantially horizontally disposed fracturing borehole forms fractures in the subterranean formation;

introducing an additional quantity of liquified gas into the at least one substantially horizontally disposed fracturing borehole;

permitting the additional quantity of liquified gas to vaporize in the at least one substantially horizontally disposed fracturing borehole whereby a resulting increase in pressure in the at least one substantially horizontally disposed fracturing borehole forms additional fractures in the subterranean formation.