METHOD FOR WELL CEMENTATION Russian patent published in 1994 - IPC

FIELD: well cementation. SUBSTANCE: method consists in injection of grouting mortar into casing or cementing string. Bridge plug is lowered. Bridge plug has axial channel shutoff by direct-acting valve which is designed to open under the action of pressure exceeding the pressure of forcing the grouting mortar into we,,. After lowering of bridge plug a portion of fluid for mixing with grouting mortar is injected. Fluid is treated with accelerator of setting of grouting mortar. This portion of fluid is injected together with displacing fluid. Volume of the portion should exceed the volume of mixing fluid with displacing fluid. Then, grouting mortar is displaced to casing string-borehole annulus and to interval to be cemented. Grouting mortar in casing string-borehole annulus is acted by excessive pressure. Additional injection is effected after completion of forcing of grouting mortar. Excessive pressure equals the pressure of forcing of grouting mortar and maintained during the time up to the onset of setting of grouting mortar. EFFECT: higher efficiency.