Abstract: A method is disclosed for recovering methane from a solid carbonaceous subterranean formation having a production well in fluid communication with the formation and an injection well in fluid communication with the formation. In the method an oxygen-depleted effluent, produced by a cryogenic separator is injected into the formation through the injection well. A first methane-containing gaseous mixture is recovered from the formation through the production well-during at least a portion of the time the oxygen-depleted effluent is being injected into the formation. The first methane-containing gaseous mixture has a first methane-desorbing gas volume percent. The injection of oxygen-depleted effluent is ceased and thereafter a second methane-containing gaseous mixture is recovered from the formation which has a second methane-desorbing gas volume percent which is less than the first methane-desorbing gas volume percent.

Abstract: A method for treating a mixture of gaseous fluids within a solid carbonaceous subterranean formation. In some embodiments, the invention provides for the disposal of a strongly adsorbing gaseous fluid within the formation. In other embodiments, the invention provides a means for fractionating a mixture of gaseous fluids within the formation. In still other embodiments, the invention provides for the recovery of a raffinate from the formation which is enriched in relatively weaker adsorbing gaseous fluids. In still other embodiments, the invention provides for the recovery of methane from the formation.

Abstract: A method is disclosed for recovering methane from a solid carbonaceous subterranean formation having a production well in fluid communication with the formation and an injection well in fluid communication with the formation. In the method an oxygen-depleted effluent, produced by a cryogenic separator is injected into the formation through the injection well. A first methane-containing gaseous mixture is recovered from the formation through the production well during at least a portion of the time the oxygen-depleted effluent is being injected into the formation. The first methane-containing gaseous mixture has a first methane-desorbing gas volume percent. The injection of oxygen-depleted effluent is ceased and thereafter a second methane-containing gaseous mixture is recovered from the formation which has a second methane-desorbing gas volume percent which is less than the first methane-desorbing gas volume percent.

Abstract: A method for disposing of unwanted gaseous fluid components, such as carbon dioxide, oxides of nitrogen, hydrogen sulfide, and oxides of sulfur within a solid carbonaceous subterranean formation, such as a coal seam. The unwanted gaseous fluid components are typically contained in a gaseous process effluent stream which is introduced into the formation.

Abstract: A method for treating a mixture of gaseous fluids within a solid carbonaceous subterranean formation. In some embodiments, the invention provides for the disposal of a strongly adsorbing gaseous fluid within the formation. In other embodiments, the invention provides a means for fractionating a mixture of gaseous fluids within the formation. In still other embodiments, the invention provides for the recovery of a raffinate from the formation which is enriched in relatively weaker adsorbing gaseous fluids. In still other embodiments, the invention provides for the recovery of methane from the formation.

Abstract: A method for improving the recovery of methane from a solid carbonaceous subterranean formation penetrated by a wellbore, the method comprising the steps of introducing a first fluid into the formation which sorbs to the formation, allowing at least a portion of the first fluid to sorb to the formation, introducing a chemically different second fluid into the formation at a pressure higher than the parting pressure of the formation, relieving pressure within the formation to produce shear failure within the formation, and repeating the introduction of second fluid and the relieving of pressure until a desired permeability of the formation is obtained.

Abstract: A method of recovering methane from a solid carbonaceous subterranean formation having a production well in fluid communication with the formation and an injection well in fluid communication with the formation, comprising the steps of passing a gaseous fluid containing at least 60 volume percent nitrogen and at least 15 volume percent oxygen through a membrane separator to produce an oxygen-depleted effluent, pressurizing the oxygen-depleted effluent to a pressure above a reservoir pressure of the solid carbonaceous subterranean formation, injecting the oxygen-depleted effluent into the formation through the injection well, and recovering a fluid comprising methane through the production well.

Abstract: A method is disclosed for using a pressure swing adsorption separator system to provide an oxygen-depleted gaseous effluent for injecting into a suitable solid carbonaceous subterranean formation, such as a coalbed, to enhance the recovery of methane from the formation.

Abstract: A method is disclosed for increasing the production of methane from a solid carbonaceous subterranean formation having a standard initial production rate of a methane-containing gas of X standard cubic feet per unit time. The method comprises the steps of injecting an inert methane-desorbing gas into the formation; terminating injection of the methane-desorbing gas; and thereafter recovering greater than X standard cubic feet per unit time of a methane-containing gas from the formation. In some embodiments, a number of well systems exceeding the number of available inert gas production and injection units can be operated in accordance with the present invention to yield greater methane-containing gas production than would be obtained if the available injection systems were dedicated continuously to particular well systems.

Abstract: A method for reducing the inert gas fraction volume percent present in a methane-containing mixture produced by injecting an inert gas into a solid carbonaceous subterranean formation is disclosed. The method reduces the inert gas fraction by suspending the injection of the inert gas or by reducing a rate of injection of the inert gas. Additional methods are disclosed in which the inert gas volume percent of a gaseous mixture produced from more than one well can be maintained below the inert gas volume percent present in a gas obtained from at least one of the wells.

Abstract: A method of recovering methane from a solid carbonaceous subterranean formation by injecting a fluid that desorbs methane through at least one injection well into a subterranean formation and recovering desorbed methane through at least one production well. The initial rate of injection of the desorbing fluid can be increased without exceeding formation pressure limitations by injecting a preflush fluid having a desorbing efficiency less than a desorbing efficiency of the first fluid. This increase in injection of the desorbing fluid results in an increase in the recovery rate of methane.

Abstract: A method of recovering methane from a solid carbonaceous subterranean formation includes injecting a gas that desorbs methane through an injection well into a subterranean formation and recovering methane from a first and a second production wells, or from a first and a second layer. Areal and/or vertical sweep efficiency of the injected desorbing gas can be increased by selectively restricting the flow of recovered fluids from the first or the second production well with the highest monitored ratio of injected desorbing gas. The restriction of flow forces the desorbing gas into higher permeability areas of the subterranean formation.

Abstract: A method of increasing the rate of methane production from a coal seam includes introducing a desired volume of a gas, that causes coal to swell, into the coal seam adjacent a wellbore, maintaining the coal seam adjacent the wellbore in a pressurized condition for a period of time to permit the gas to contact a desired area of the coal adjacent the wellbore, and relieving the pressure within the coal seam by permitting fluids to flow out from the wellbore at a rate essentially equivalent to the maximum rate permitted by the wellbore and any surface wellbore flow control equipment. Uneven stress fractures should be created in the coal by this method which will increase the near wellbore permeability of the coal seam.

Abstract: Disclosed herein is a method of degasification, wherein gas and water production from a coal field are maintained at high rates regardless of temporary changes in market demand. While all the produced water is disposed, surplus gas is reinjected in coal by converting some of the producers to injectors. When the demand for gas improves, the injection wells are put back on production. Recovery of gas from wells used as injectors is rapid because of increased reservoir pressure and high gas relative permeability near the wellbore.