Method for plugging gas migration channels in the cement annulus of a wellbore using high viscosity polymers

Abstract From the Canadian patent

A process for mitigating the effects of gas migration through channels in a cement sheath in a hydrocarbon production well by injecting a mixture of a carrier fluid with a dissolved polymer into the sheath and dropping the polymer out of solution to form polymers to plug the channels. The process utilizes the phase transition parameters of the mixture coupled with well conditions and/or injection parameters to cause the polymer to drop out of solution within the gas migration channels. The mixture can be injected through well perforations in the producing zone or perforations made in the wellbore adjacent the gas migration zone or directly into the cement sheath at the wellhead.