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U.S. Department of Energy
Office of Scientific and Technical Information

Insulating tubular conduit apparatus

Patent ·
OSTI ID:6961829

This patent describes 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. The conduit comprises 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 the outer tubular member; and insulating material surrounding the inner tubular member. The inner tubular member has 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 the inner tubular member is thereby rigidly sealably secured to the adjacent ends of the outer tubular member to define a sealed cavity between the tubular members. The rigidly welded, flared ends comprise 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 are respectively welded to the inner surface of the outer tubular conduit at a position intermediate the length of the threads on each end thereof.

Assignee:
Baker Oil Tools, Inc., Orange, CA
Patent Number(s):
US 4624485
OSTI ID:
6961829
Country of Publication:
United States
Language:
English