PLUGGING MATERIAL AND A METHOD FOR PREPARATION THEREOF Russian patent published in 2007 - IPC C09K8/467 

FIELD: oil and gas production.

SUBSTANCE: invention relates to expandable plugging materials and can find use in cementation of drill string-casing annulus in oil and gas wells within temperature range 10-30°C. Plugging material, wt %: caustic magnesite powder 48.61-50.43, magnesium chloride 12.75-13.80, sodium tripolyphosphate 1.00-1.96, double superphosphate 0.25-0.50, starch-containing reagent 0.12-0.37, and water - the balance, wherein magnesium chloride utilized is bischofite and starch-containing reagent is extrusion starch-containing reagent or modified swellable starch-containing reagent. In a plugging material preparation method involving tempering of dry mix based on caustic magnesite powder with tempering liquid, said dry mix is a mix composed of caustic magnesite powder, sodium tripolyphosphate, and starch-containing reagent, while tempering liquid is magnesium chloride solution supplemented by double superphosphate. As a result, plugging material is obtained based on magnesia binder, whose solution is characterized by acceptable thickening time values and setting times, high sedimentation stability combined with processibility of preparation thereof, while cement stone is characterized by high mechanical strength and elevated values of expansion, which, in absence of water and air moisture, ensures formation of strong and fluid-impermeable contact with both casing strings within annulus.

EFFECT: enhanced plugging material preparation efficiency and improved cement stone characteristics.

4 cl, 1 tbl