Full bore internal tieback system and method
In a subsea well assembly having a tubular wellhead housing having a bore, the improvement is described comprising in combination: a counterbore in the bore of the wellhead housing; a tieback profile in the counterbore; a protective sleeve releasably secured in the counterbore and covering the tieback profile, the protective sleeve being movable to expose the tieback profile when it is desired to tieback the subsea well assembly; a tieback funnel which is configured to land on the rim of the wellhead housing when it is desired to tieback the subsea well assembly; and a tieback sleeve carried by the tieback funnel, having a profile on its exterior which is configured to engage the tieback profile in the counterbore after the protective sleeve has been moved to secure the tieback funnel to the wellhead housing, the tieback sleeve having a bore that has a diameter at least equal to the diameter of the bore immediately below the counterbore. A method of drilling and tying back a subsea well is described which includes the steps of installing an outer wellhead housing with conductor pipe extending into the well, then drilling the well to a greater depth, the improvement comprising: providing an inner wellhead housing with a bore, a rim, a counterbore extending downward from the rim, a tieback profile in the counterbore, and a sealing area located below the counterbore; releasably installing a protective sleeve in the counterbore so as to cover the tieback profile; securing a string of casing to the inner wellhead housing and landing the inner wellhead housing in the outer wellhead housing; drilling the well to a greater depth with the protective sleeve located in the counterbore; securing another string of casing to a casing hanger, landing the casing hanger in the inner wellhead housing, cementing the second string of casing in the well, and sealing the casing hanger to the sealing area of the bore of the inner wellhead housing.
- Assignee:
- ABB Vetco Gray Inc., Houston, TX (United States)
- Patent Number(s):
- A; US 5222560
- Application Number:
- PPN: US 7-870021
- OSTI ID:
- 6341829
- Country of Publication:
- United States
- Language:
- English
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