초록 ▼

A concentric insulating tubular conduit member for use in forming a conduit string, such as a tubing string in a subterranean well, is disclosed. Each individual concentric conduit comprises an outer tubing and an outwardly flared inner tubing welded to the outer tubing at the end of the flared sect

A concentric insulating tubular conduit member for use in forming a conduit string, such as a tubing string in a subterranean well, is disclosed. Each individual concentric conduit comprises an outer tubing and an outwardly flared inner tubing welded to the outer tubing at the end of the flared section. The inner tubing member is formed from an initially straight cylindrical member having enlarged ends and, when outwardly flared, the flared ends, although stretched, have a thickness at least equal to the nominal thickness of the inner tubular member. Insulation may be contained within the annular cavity between the inner and outer tubing members and between inner and outer coupling members at the juncture between adjacent tubing sections.

대표청구항 ▼

A concentric walled tubular conduit forming a tubular string in a subterranean well to transport a fluid between the surface and a subterranean producing formation in an oil well, the temperature of the fluid being greater than the surrounding temperature in the well, comprising: an outer tubular me

A concentric walled tubular conduit forming a tubular string in a subterranean well to transport a fluid between the surface and a subterranean producing formation in an oil well, the temperature of the fluid being greater than the surrounding temperature in the well, comprising: an outer tubular member prestressed in compression and having threads on each end thereof; an inner tubular member prestressed in tension, and concentrically received within and spaced from the inner periphery of said outer tubular member; insulating material surrounding said inner tubular member; said inner tubular member having both of its ends outwardly flared and respectively welded directly to the inner surface of the outer tubular member adjacent the threaded ends; each end of said inner tubular member being thereby rigidly sealably secured to the adjacent ends of said outer tubular member to define a sealed cavity between said tubular members; the rigidly welded, flared ends comprising means for transmitting forces due to differential thermal expansion and contraction along the entire length of the inner and outer tubular members between the outer and inner tubular members, differential thermal expansion forces being transmitted through the flared ends and the welds; both ends of the inner tubular conduit being respectively welded to the inner surface of the outer tubular conduit at a position intermediate the length of the threads on each end thereof.