Patent ID: 6763891
Filing Date: 2004-07-20
Classification: E21B

Abstract:
In a wellhead assembly having a production tree with a bore into which a tubing hanger lands and is sealed by a tubing hanger seal, the tubing hanger adapted to be connected to a string of tubing, defining a tubing annulus, the tubing hanger having an axial passage with a lateral production port that registers with a lateral production passage in the tree for the flow of production fluid from the tubing, the improvement comprising:a first portion of a tubing annulus passage extending upward through a portion of the tree from the tubing annulus to an exterior port, the exterior port adapted to be connected to a source of fluid for injection into the tubing annulus; a second portion of the tubing annulus passage extending upward through a portion of the tree from the exterior port to the bore of the production tree above the tubing hanger seal; a lower valve in the first portion of the tubing annulus passage for selectively opening and closing the first portion of the tubing annulus passage; the bore above the tubing hanger seal being free of any additional seals, exposing the tubing hanger above the tubing hanger seal to ambient pressure that exists externally of the tree; and two closure members located in the second portion of the tubing annulus passage outside of the bore of the tree in series with each other, for selectively opening and closing the second portion of the tubing annulus passage.