METHOD AND DEVICE FOR THIEF FORMATION ISOLATION INSIDE WELL Russian patent published in 2008 - IPC E21B33/13 E21B27/02 

FIELD: oil production, particularly methods or devices for cementing, for plugging holes, crevices, or the like.

SUBSTANCE: method involves forcing plugging solution in reservoir by pressure increase under the action of mixture including 40% hydrogen peroxide and stabilizing agent, namely sodium benzoate, added in amount of 2-3% by weight, wherein hydrogen peroxide is taken in amount of 5-8% of dry plugging mix mass and said pressure is increased up to pressure jump sufficient to be picked-up by manometer; creating backpressure in flow string interior; performing low-speed drilling string rotation up to plugging solution setting. Device comprises container, piston arranged inside container and separating container into over-piston and under-piston zones. Bottom with seat and medium bottom are defined inside container. Pipe with discharge windows and low bottom is fixedly connected with lower container part. Auger is secured to lower pipe bottom. Discharge windows are grouped in several rows and made as radially directed orifices extending along pipe height. Bottom seat is arranged over discharge windows. Bottom with seat and medium bottom are created of easy-breakable material. Sealed polyethylene vessel filled with water is installed between the piston and medium bottom. Water volume in the vessel is equal to inner volume of pipe provided with discharge windows. Upper container part has discharge and overflow valves.

EFFECT: increased thief formation isolation efficiency.

2 cl, 1 dwg