COMPOSITION FOR INSULATION OF FORMATION WATER INFLOW AND A METHOD TO PREPARE THE SAME Russian patent published in 2006 - IPC C09K8/42 

FIELD: oil and gas production.

SUBSTANCE: water-based composition for insulation of formation water inflow, which can also be used to control development of oil deposits, containing 5.0-15.0% exopolysacharide produced by Azotobacter vinelondi (Lipman), VKMP N-5933, in the form of culturing liquid and 0.01-0.15% polyvalent metal salt further contains 0.1 to 5.0% of water-absorbing polymer as filler, which is tempered in inert carrier (anhydrous hydrocarbon solvent) functioning as buffer to separated composition from water during injection of composition into well, provided that water-absorbing polymer-to-inert carrier ratio ranges between 1:5 and 1:10. Composition can also contain superfine hydrophobic material in amount 0.1 to 3.0%. In a method for preparing above-defined composition, including preparation of aqueous solution of indicated exopolysacharide, addition of polyvalent metal salt, and stirring to achieve homogeneous mass, said water-absorbing polymer is preliminarily tempered in said inert carrier and injected before injection of aqueous solution of exopolysacharide with polyvalent metal salt. Once tempered, water-absorbing polymer can be supplemented by superfine hydrophobic material in amount 0.1-2.0%. Prior to adding polyvalent metal salt to aqueous solution of exopolysacharide, a surfactant or a mixture of surfactants can be added to the solution in amount between 0.1 and 3.0 wt %. Composition according to invention allows efficiency of insulation operations in high-permeability intervals of washed nonuniform fractured reservoir to be increased, in particular, reducing watering in high-permeability intervals, resulting in higher oil recovery of formation due to variation in wettability, namely increased hydrophobic power of composition and improved its adhesion to rock leading to lower permeability of highly watered interlayers, increased hydrophobicity of rock surface, and increased relative permeability of formation for hydrocarbon phase before aqueous phase because of high oil-displacement properties of composition.

EFFECT: improved oil production conditions and increased oil recovery.

6 cl, 2 tbl, 4 ex