CASING PIPE FOR WELL CASING Russian patent published in 1995 - IPC

FIELD: well drilling; applicable as a component of casing string in intervals of possible crossflows between beds. SUBSTANCE: casing pipe for well casing has main pipe and shell which form tight annular space filled with gas at pressure not above atmospheric one. Shell is made in form of rigid pipe and installed for axial shifting and rotation that provides for preservation of cement stone and full sealing of casing external surface-cement ring contact at any types of operation in well dealing with varied pressure and temperature of well fluid. EFFECT: higher efficiency. 1 dwg