Increased methane production from a subterranean carbonaceous formation using a gaseous oxidant to promote cleat formation

摘要

A method for increasing the production of methane from a subterranean carbonaceous formation, for example containing clay minerals, by injecting a gaseous oxidizing solution into said formation through an injection well. The oxidising agent stimulates chemically the formation of cleats or fractures in a coal formation through which methane can diffuse. As the free surface area of the cleat system increases thus the gas permeability of the seam increases. This results in an increased rate of methane desorption from the formation. The preferred gaseous oxidising agent contains at least one of the group comprising ozone, oxygen, or combinations thereof, with gaseous streams containing between 23 to 35 % oxygen being most preferred. The methane may be recovered through the same well used for injecting the oxidising solution or through a separate recovery well. The oxidant is normally shut-in the well for a selected period before methane collection begins.