Patent attributes
A subsurface annular safety barrier including a tubing disposed within a wellbore casing forming a casing-tubing annulus to allow fluid flow from and/or to a subterranean formation, and an annular barrier carried by the tubing and positioned in the casing-tubing annulus proximate the top of a formation, separating communication between the formation and the upper portion of the casing-tubing annulus above the annular barrier, wherein the annular barrier is set in an open position to allow fluid communication between the formation and the upper portion of the casing-tubing annulus and operationally activatable, without mechanical manipulation of a pipe string, to a closed position to prevent undesired fluid flow between the formation and upper portion of the casing-tubing annulus.
