METHOD FOR CEMENTING AUXILIARY STRING AT WELL WORKOVER Russian patent published in 2015 - IPC E21B33/14 

FIELD: oil and gas industry.

SUBSTANCE: invention suggests method for cementing auxiliary string with stages whereat geophysical survey of the well is performed in order to indentify state of the production string, location of disturbed intervals and perforated intervals; assembly of auxiliary string is run in and set at depth identified by results of geophysical survey of the well; grout injection equipment for is run in to the well; design volume of cement grout is prepared and injected to auxiliary string; displacing fluid is injected to the auxiliary string so that cement grout fills tubing-casing annulus; the well is withhold for waiting-on-cement time. At that according to results of geophysical survey length of cemented auxiliary string, quantity and mounting locations for sealing devices at the auxiliary string are determined on the basis of their next position at distance of 8-12 m higher and lower than disturbed intervals and at distance of 8-12 m over the upper boundary of perforated interval. The auxiliary string is assembled by installation of sealing devices in compliance with data obtained at the stage of mounting locations identification for sealing devices and by mounting positive centralizers above and below the sealing devices, at that installation of sealing devices is performed in the following way: the upper limiting ring, self-sealing rubber cup, cone-shaped thrust with lobes and gaps allowing passage of cement grout are put onto the auxiliary string bottom-up, at that limiting ring and cone-shaped thrust are fixed rigidly at the auxiliary string.

EFFECT: improved efficiency of well workover.

3 cl, 2 dwg