METHOD FOR STRENGTHENING OF WELL Russian patent published in 1998 - IPC

FIELD: oil and gas production industry. SUBSTANCE: according to method, after seating of separation plug on thrust ring and obtaining stop pressure on completion of forcing-through of cement slurry into annular space, pressure in casing string is reduced down to value which is not less than difference of hydrostatic pressures at well bottom-hole by columns of cement slurry and forcing-through liquid. Casing string is subjected to excessive pressure for no shorter time than up to start of hardening but not for longer than 2/3 of period of cement slurry hardening. This prevents bending of lower part of casing string during period of waiting for hardening of cement slurry and improves quality of well strengthening. EFFECT: higher efficiency.