Tubing hanger and wellhead housing with mating tubing annulus passages

Abstract

A subsea wellhead assembly has a tubing annulus path that extends partly through the tubing hanger and partly through the wellhead housing. A tubing hanger tubing annulus passage extends through part of the tubing hanger from a lower port on the lower end of the tubing hanger to an upper port on the exterior surface of the tubing hanger below the tubing hanger seal. A wellhead housing tubing annulus passage within the sidewall of the wellhead housing has a lower end at the bore below the tubing hanger seal and an upper end at the bore above the tubing hanger seal. A valve is mounted to the wellhead housing and accessible by an ROV from the exterior for opening and closing the inner wellhead housing tubing annulus passage.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a vertical sectional view illustrating a wellhead assembly constructed in accordance with this invention

FIG. 2 is a enlarged vertical sectional view of a portion of the wellhead assembly of FIG. 1.

Claims

1. A wellhead assembly, comprising: a wellhead member having a tubular sidewall defining a bore;a tubing hanger landed in the bore for supporting a string of tubing, the tubing hanger having a production passage for fluid communication with the interior of the string of tubing;a tubing hanger seal surrounding the tubing hanger and sealing an exterior surface of the tubing hanger to the bore;a tubing hanger tubing annulus passage extending alongside the production passage from a lower port on a lower portion of the tubing hanger to an upper port on the exterior surface of the tubing hanger below the tubing hanger seal; anda wellhead member tubing annulus passage within the sidewall of the wellhead member, having a lower end at the bore below the tubing hanger seal for communication with the upper port of the tubing hanger tubing annulus passage and an upper end at the bore above the tubing hanger seal.

2. The wellhead assembly according to claim 1, further comprising: a valve mounted to the wellhead member for opening and closing the wellhead member tubing annulus passage.

3. The wellhead assembly according to claim 2, further comprising: an ROV actuator on the valve to enable the valve to be opened and closed by an ROV.

4. The wellhead assembly according to claim 1, further comprising: a cavity formed in the wellhead member in communication with the wellhead member tubing annulus passage; anda valve mounted in the cavity for opening and closing the wellhead member tubing annulus passage.

5. The wellhead assembly according to claim 1, further comprising: a production tree mounted on top of the wellhead member, the production tree having a production passage;an isolation sub extending from the production passage into sealing engagement with the production passage in the tubing hanger for communicating well fluid from the tubing to the production passage in the tree; anda production tree tubing annulus passage within the tree and having a lower end adjacent the isolation sub for communicating with the upper end of the wellhead member tubing annulus passage.

6. The wellhead assembly according to claim 1, further comprising: a casing hanger landed in the bore of the wellhead member for supporting a string of casing; and whereinthe lower portion of the tubing hanger extends into the casing hanger.

7. The wellhead assembly according to claim 1, wherein the wellhead member comprises: an inner wellhead housing; and wherein the wellhead assembly further comprises:an outer wellhead housing, the inner wellhead housing landing within the outer wellhead housing and protruding above.

8. The wellhead assembly according to claim 1, further comprising: an annular gallery area between the exterior surface of the tubing hanger and the bore of the wellhead member in fluid communication with the upper port of the tubing hanger tubing annulus passage and the lower end of the wellhead member tubing annulus passage.

9. A wellhead assembly, comprising: an outer wellhead housing secured to a first string of casing;an inner wellhead housing having a lower portion landed in the outer wellhead housing and secured to a second string of casing, the inner wellhead housing having a tubular sidewall defining a bore;a casing hanger landed in the bore of the inner wellhead housing and secured to a third string of casing;a tubing hanger landed in the bore of the inner wellhead housing, the tubing hanger having a lower end extending into the casing hanger and secured to a string of tubing, the tubing hanger having a production passage extending from the lower end to an upper end of the tubing hanger for flowing well fluid from the string of tubing;a tubing hanger seal surrounding the tubing hanger and sealing an exterior surface of the tubing hanger to the bore above the casing hanger;a tubing hanger tubing annulus passage extending alongside the production passage in the tubing hanger from a lower port on the lower end of the tubing hanger to an upper port on the exterior surface of the tubing hanger above the casing hanger and below the tubing hanger seal;an inner wellhead housing tubing annulus passage extending vertically within the sidewall of the inner wellhead housing, having a lower end at the bore below the tubing hanger seal for communication with the upper port of the tubing hanger tubing annulus passage and an upper end at the bore above the tubing hanger seal; anda valve mounted to the inner wellhead housing and accessible from an exterior of the inner wellhead housing for opening and closing the inner wellhead housing tubing annulus passage.

10. The wellhead assembly according to claim 9, further comprising: an annular gallery area between the exterior surface of the tubing hanger and the bore of the inner wellhead housing in fluid communication with the upper port of the tubing hanger tubing annulus passage and the lower end of the inner wellhead housing tubing annulus passage.

11. The wellhead assembly according to claim 9, further comprising: an ROV actuator on the valve to enable the valve to be opened and closed by an ROV.

12. The wellhead assembly according to claim 9, further comprising: a cavity formed in the sidewall of the inner wellhead housing in communication with the inner wellhead housing tubing annulus passage; and whereinthe valve is mounted in the cavity.

13. The wellhead assembly according to claim 9, further comprising: a production tree mounted on top of the inner wellhead housing, the production tree having a production passage;an isolation sub extending from the production passage in the tree into sealing engagement with the production passage in the tubing hanger for communicating well fluid from the tubing to the production passage in the tree; anda production tree tubing annulus passage within the tree and having a lower end adjacent the isolation sub for communicating with the upper end of the inner wellhead housing tubing annulus passage.

14. The wellhead assembly according to claim 13, further comprising: a dual concentric production riser connected to the tree and extending to a production facility, the production riser having an inner conduit that communicates with the production passage in the tree, the production riser having an outer conduit that defines an annulus between the inner and outer conduits that communicates with the tree tubing annulus passage.

15. A method of drilling and completing a subsea well, comprising: (a) providing a tubing hanger having a production passage, a tubing hanger seal, a tubing hanger tubing annulus passage extending from a lower portion of the tubing hanger upward to an upper port on the exterior of the tubing hanger below the tubing hanger seal;(b) providing a wellhead housing having a bore and a wellhead housing tubing annulus passage with a lower end and an upper end, both terminating at the bore;(c) with a drilling vessel, installing a wellhead housing at the sea floor, connecting a drilling riser to the wellhead housing and drilling through the riser and the wellhead housing to a selected depth;(d) running a string of casing through the riser and landing a casing hanger in the wellhead housing;(e) securing the tubing hanger to a string of production tubing, lowering the tubing hanger and production tubing through the drilling riser, landing the tubing hanger in the bore of tile wellhead housing, and sealing the exterior of the tubing hanger to the bore with tile tubing hanger seal located between the lower and upper ends of the wellhead housing tubing annulus passage; and(f) Circulating fluid from the drilling vessel along a flow path defined by a tubing annulus surrounding the production tubing, the tubing hanger tubing annulus passage, and the wellhead housing tubing annulus passage.

16. The method according to claim 15, wherein: step (b) further comprises mounting a valve in the wellhead housing tubing annulus passage; and wherein the method further comprises:closing the valve after step (f).

17. The method according to claim 16, wherein the step of closing the valve is performed with an ROV.

18. The method according to claim 15, further comprising after step (e) and before step (f), disconnecting the drilling riser from the wellhead housing, landing a production tree on the wellhead housing, and performing step (f) by circulating through passages in the tree.

19. The method according to claim 15, wherein comprising after step (e) and before step (f): disconnecting the drilling riser from the wellhead housing;landing a production tree on the wellhead housing, the production tree having a production passage and an annulus passage, each having access at an upper end of the tree;connecting a dual concentric riser to the production tree, with an inner conduit in communication with the production passage and an outer conduit in communication with the annulus passage; thenpumping down one of the conduits and returning fluid up the other of the conduits to perform step (f).

20. The method according to claim 19, further comprising producing production well fluid through the tubing, the production passages in the tubing hanger and the tree and up the inner conduit of the dual concentric riser.