METHOD OF WELL TWO-STAGE CEMENTING Russian patent published in 2003 - IPC

FIELD: oil and gas producing industry; applicable in stage cementing of wells with producing formations presented by fissured and high-permeability reservoirs. SUBSTANCE: method includes running into well of casing string with landing adapter, cementing valve, shoe in lower part, and devices for stage cementing located on hollow plugs. Plugs are installed on casing string and their bottom part projects inside casing string, and they have weakened cross-section. Devices are installed above producing formation. Lowered into casing string are tubings with sealing nipple at their end and shearing sleeve which destroys hollow plugs. Sealing nipple is fitted into landing adapter. Cement mortar of the first stage is injected through tubings somewhat above devices. Injection is continued until moment of forcing plug entering into landing adapter. Sealing nipple is withdrawn from landing adapter, and annular space is sealed. Cement mortar is removed. Tubings are lifted to level of sealing nipple position, and cement mortar setting is waited. Then cement mortar of the second stage is injected through tubings and said devices with annular space closed. Small volume of cement mortar is left in wellbore. After forcing of cement mortar, pressure is reduced, and that cement mortar is removed through tubing. Cement mortar setting is waited. EFFECT: provision of required quality of cement stone behind casing string and considerable saving of material means. 5 dwg