Wells – Submerged well – Testing
Reexamination Certificate
1998-10-02
2001-02-13
Lillis, Eileen D. (Department: 3673)
Wells
Submerged well
Testing
C166S348000
Reexamination Certificate
active
06186237
ABSTRACT:
TECHNICAL FIELD
This invention relates in general to subsea wellheads, and in particular to a tubing hanger having a production passage, an annulus passage, and a retrievable check valve in the annulus passage.
BACKGROUND ART
A common method of completing a subsea well involves installing a high pressure wellhead housing at the sea floor. Multiple strings of casing will be supported at the wellhead housing and extend into the well. Then a tubing hanger with a string of tubing and other downhole equipment such as a packers, will be run into the casing and landed in the wellhead housing. The steps of drilling through the high pressure wellhead housing, running the casing and running the tubing are performed through a drilling riser and blowout preventer.
The tubing hanger running tool will normally be attached to a dual completion riser which has one conduit in communication with a production bore in the tubing hanger and another conduit in communication with an annulus bore in the tubing hanger. The production and annulus bores are parallel to and offset from each other. Tubing annulus communication is needed for certain operations during completion. After the tubing string has been landed and the tubing hanger set, the operator runs plugs on wireline through the completion riser conduits, one plug sealing the annulus bore and the other plug sealing the production bore.
The operator then removes the dual string completion riser and the drilling riser along with the blowout preventer. The operator then runs a Christmas tree, landing the tree on the wellhead housing and completing the well. The wireline plug(s) in the production bore and annulus are removed for production.
It is expensive for a drilling rig to have a dual string completion riser in addition to a drilling riser. It would be preferable to be able to run the dual bore tubing hanger through the drilling riser on a single monobore conduit such as a string of drill pipe. Running on a drill string, however, does not readily allow a wireline plug to be installed in the annulus bore in the tubing hanger, because the drill string bore is aligned with the production bore. Tubing hangers with various valves for the annulus have been proposed, but have not been used extensively because of reliability concerns. Check valves have been used in the tubing hanger annulus bore in the past, but are not in general use because of reliability concerns and because of the inability of being able to test from above prior to removing the blowout preventer.
DISCLOSURE OF INVENTION
In this invention, the tubing hanger has a check valve located in the annulus bore. The running tool runs the tubing hanger on a monobore string while holding the check valve in the open position. After setting and testing, the running tool is lifted and the 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.
In one embodiment, the installation of the annulus plug is handled by retrieving the running tool. A retrieval tool is lowered into engagement with the tubing hanger. The retrieval tool is configured to align the annulus bore with the drill string passage. A wireline tool will be lowered through the drill string to retrieve the check valve and install the plug.
In the other embodiment, the check valve remains in the tubing hanger and the plug is set in the annulus bore above it. The check valve is retained in the open position.
REFERENCES:
patent: 3800869 (1974-04-01), Herd et al.
patent: 3847215 (1974-11-01), Herd
patent: 4223738 (1980-09-01), Boutet et al.
patent: 4474236 (1984-10-01), Kellet
patent: 4958686 (1990-09-01), Putch
patent: 5143158 (1992-09-01), Watkins et al.
patent: 5769162 (1998-06-01), Bartlett et al.
patent: 2291085A (1996-01-01), None
patent: 2311545 (1997-10-01), None
patent: 2311544A (1997-10-01), None
patent: WO 97/11253 (1997-03-01), None
Bridges Charles D.
Voss, Jr. Robert K.
ABB Vetco Gray Inc.
Bradley James E.
Felsman, Bradley, Vaden, Gunter & Dillon L.L.P.
Lagman Frederick L.
Lillis Eileen D.
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