Patent attributes
A work string locatable in a borehole so as to form an annulus around the work string and a method of depressurizing the annulus are provided. The work string includes a packer expandable radially out from the work string to seal the annulus and a packer sub positioned below the packer including a sub body and a check valve in the body and operable to permit fluid in the annulus to flow into the work string and prevent fluid in the work string from flowing into the annulus. The check valve is operable to open and permit fluid in the annulus to flow into the work string upon exertion of a predetermined minimum pressure on the check valve by the fluid in the annulus. The method includes providing the work string in the borehole and depressurizing the annulus by permitting fluid in the annulus to flow through the check valve.