Patent ID: 6877566

Claim:
A method for causing pressure variations in a wellbore which is in fluid communication with a subject formation, the method utilizing a valve device comprising a valve mechanism and an associated fluid passage, the wellbore extending between an upper surface end and the subject formation, at least the valve mechanism of the valve device and a lower end of the fluid passage being positioned within the wellbore, wherein the valve device may be actuated between an open position and a closed position, the wellbore being provided with a sealing device positioned in the wellbore above a lower end of the subject formation, wherein the sealing device is associated with the valve device such that when the valve device is in the closed position, the wellbore is sealed below the sealing device, the method comprising: (a) allowing a fluid from the subject formation to enter the wellbore below the sealing device while the valve device is in the closed position so that a pressure in the wellbore below the sealing device is increased, wherein the subject formation is comprised of a coal seam, wherein the wellbore has a perimeter, wherein the wellbore comprises a section which extends within the subject formation, wherein a casing extends substantially around the perimeter of the wellbore and substantially throughout the section of the wellbore which extends within the subject formation, and wherein at least a portion of the casing is perforated or cut; (b) actuating the valve device to the open position to allow the fluid to pass through the fluid passage toward the surface end of the wellbore; (c) actuating the valve device to the closed position after a predetermined delay following actuation of the valve device to the open position; and (d) repeating step (a) and the steps following step (a).