METHOD OF PRODUCING FORMATION ISOLATION IN CEMENTING OF CASING STRING Russian patent published in 2002 - IPC

FIELD: oil producing industry; technology of well construction; applicable in casing and cementing of wells drilled for oil, gas and water. SUBSTANCE: method includes lowering of casing string equipped with device for isolation of producing formation into well, injection of cement slurry into annular space behind casing string, and isolation of well annular space. Isolation of well annular space is effected by injection of hydrophobic slurry with density equalling that of cement slurry into interval of producing formation. In so doing, first, cement slurry is injected and separating plug is installed. Then hydrophobic slurry is injected, separating plug is installed and displacing fluid is injected. Device for isolation of producing formation is used in the form of check valves located at level of producing formation floor. Displacing fluid is injected before shutoff of check valves by separating plug installed from atop of hydrophobic slurry. EFFECT: higher efficiency due to development of simple in use, reliable in operation and low-cost method. 3 dwg