THERMOISOLATED STRING Russian patent published in 1999 - IPC

FIELD: oil and gas production industry. SUBSTANCE: thermoisolated string is used in oil recovery with injection of heat-carrier into oil bed. String has internal and external rows of pipes which are located coaxially and are rigidly connected by one end with well-head equipment. Positioned in circular space between pipes is thermal-insulating material. Internal pipe at end of string lower section is provided with external thrust shoulder and is installed on coupling ring which is rigidly connected with external pipe with possibility of turning on it. Coupling ring is made in the form of bush with bores and internal shoulders. Located in upper bore between shoulders of internal pipe and coupling ring is thrust bearing. Located in lower bore of coupling ring between walls of bore and internal pipe is sealing gland with pressure flange. Aforesaid embodiment and arrangement of string components allows for ensuring higher reliability in application of thermoisolated string achieved due to prevention of twisting of internal pipe which can be caused by thermal stresses. EFFECT: higher efficiency. 2 cl, 2 dwg