Abstract: The wellhead assembly has a production tree with multiple safety barriers. A tubing hanger lands and seals in the bore of the tree. The tubing hanger has a lateral production flow passage that registers with a lateral passage in the tree. A tubing annulus passage extends upward from the tubing annulus to an exterior port. A second portion of the tubing annulus passage extends upward from the exterior port into the bore above the tubing hanger seal. The external port may be used for gas injection. If so, two closure members are located in the upper portion of the tubing annulus above the seal. The upper closure member may be either a check valve or a removable plug.

Abstract: A subsea well has a tubing hanger which has an annulus bore and a production bore. A check valve is located in the annulus bore. A running tool runs the tubing hanger on a monobore riser such as a drill string while holding the check valve in the open position. After setting and testing, the running tool is lifted and a blowout preventer is closed around the landing string. The operator monitors the choke and kill line of the drilling riser, which will be in communication with the check valve. If the check valve is leaking, an annulus plug may be installed in the annulus bore. The installation of the annulus plug may be handled by using a retrieval tool configured to align the annulus bore with the landing string passage. A wireline tool may be lowered through the landing string and retrieval tool to retrieve the check valve and install the plug. Alternately, the check valve may remain in the tubing hanger and the plug is set in the annulus bore above it.

Abstract: A subsea well has communication passages to enable annulus pressure between the inner and intermediate strings of casing to be monitored at the surface. The communication passages include a passage through the upper casing hanger. This passage registers with a passage through the tubing hanger assembly. The passage in the tubing hanger assembly registers with a passage in the tree assembly. The passage in the tree assembly has an outlet at the exterior of the tree assembly, where it connects to a communication line that extends to production equipment at the surface.