PLUGGING COMPOSITION FOR CEMENTING CASING STRING AND PROCEDURE FOR PREPARATION OF THIS COMPOSITION Russian patent published in 2009 - IPC C09K8/42 

FIELD: oil and gas industry, chemistry.

SUBSTANCE: invention refers to well boring and can be implemented in oil and gas industry and in mining, particularly at cementing casing strings when it is required to facilitate minimal low values of fluid permeability of plugging material beyond producing string. Plugging composition for cementing casing strings consists of Portland cement, and of tempering fluid - solution of structure forming composition SFC containing, wt %: methylcellulose 1-2; carbamide 5-20; water - the rest at the ratio of tempering fluid - of SFC of the said composition diluted with water solution 7-20 times - to cement equals to 0.5. The essence of the procedure of preparation of plugging composition is as follows: producing SFC is performed in stages: during the first stage fresh water of 60-90°C temperature is added to methylcellulose and carbamide and is mixed, further fresh water of 0-20°C is added to obtained suspension and is mixed to homogeneous solution, then cement is tempered with the said tempering fluid.

EFFECT: creating efficient composition for filling annular space of well facilitating production of low permeable cement stone of high mechanical strength out of standard plugging solution, also simplifying procedure of said composition preparation.

2 cl, 1 tbl, 4 ex