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US 5,862,866 AGranted
Double walled insulated tubing and method of installing same
AssigneeRoxwell International Limited
InventorJohann Springer
Life of this patent
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AssigneeRoxwell International Limited
InventorJohann Springer
Estimating the term…
A double walled insulated tubing string (46) adapted to be hung from a well head (58) has an inner tubing string (21) formed of plural inner tubes and a radially outer tubing string (22) formed of plural outer tubes, the strings being independent of one another apart from axially fixing the strings relative to one another at the top end of the tubing string, although axial fixation may also be provided at the lower end of the tubular strings if desired. An annular insulating gap (30) between the tubing strings (21, 22) is hermetically sealed at both opposing ends and may be evacuated. Inner and outer tubing strings may be run into a well using conventional oil well drilling technology and there is no mechanical connection between the inner and outer tubing strings (21, 22), especially at connections of the respective inner and outer lengths of tube. To maintain the inside of the outer tubing string (22) free from formation liquids before the inner tubing string (21) is run into the well and sealed against the outer string at its lower end, a temporary plug (31) initially closes the lower end of the outer string and is de-activated before liquid can flow through the thermally insulated dual tubing string (46).
A double walled insulated tubing string adapted to be hung from support means, said tubing string comprising inner and outer tubes with a thermally insulating gap between said inner and outer tubes, said tubing string comprising plural lengths of outer tubes mechanically connected together by force transferring means to form an outer tubing string and plural lengths of inner tubes mechanically joined together by further force transferring means to form an inner tubing string, said inner and outer tubing strings being discrete and separate from one another over substantially the whole lengths thereof so that said insulating gap is continuous from an upper end of the tubing string to a bottom end of the tubing string, and seal means located at a bottom end of the tubing string sealing between said inner and outer tubing strings thereby closing said insulating gap at said bottom end of the tubing string.
A method of installing a double walled insulating tubing string including the steps of:
A method of installing a double walled insulating tubing string including the steps of:
A double walled insulated tubing string adapted to be hung from a support means, said tubing string comprising inner and outer tubes with a thermally insulating gap between said inner and outer tubes, said tubing string comprising plural lengths of outer tubes mechanically connected together to form an outer tubing string and plural lengths of inner tubes mechanically joined together to form an inner tubing string, said inner and outer tubing strings being discrete and separate from one another over substantially the whole lengths thereof, and a removable sealing means provided at a lower end of the outer tubing string to prevent liquid ingress into the inner tubing string.
Dependencies are inferred from the claim text.