METHOD FOR DEVELOPMENT OF INHOMOGENEOUS OIL FORMATION Russian patent published in 2020 - IPC E21B43/22 

FIELD: oil industry.

SUBSTANCE: invention relates to methods for development of inhomogeneous oil formation, namely increasing oil recovery of formations at simultaneous increase of formation coverage and higher efficiency of oil displacement in heterogeneous reservoirs at late stages of deposit development. Method for development of non-homogeneous oil formation, including pumping into formation of gel-forming composition, containing an aqueous dispersion of polyacrylamide—PAA with mol % not less than 5·10⁶ D and degree of hydrolysis of 5–20 % and sodium salt of polyanionic cellulose—PAC, filler, cross-linking agent—chromium acetate, then—additionally pumping of fringe of mixture containing water solution of nonionic surfactant—NIS—oxyethylated alkylphenol with weight ratio of ethylene oxide 70 %, process holding for gelation envisages the following. Aluminosilicate hollow microspheres ASHM-500 are used as filler, PAC—with high degree of substitution 95 % high viscous. Components ratio is as follows, wt %: PAA—0.3–1.0, high-viscosity PAC—HVPAC—0.05, chrome acetate—0.035–0.105, said microspheres—0.005–0.6, water—balance. Weight ratio of PAA and HVPAC to chromium acetate is 10:1. Aqueous rim of the mixture contains oxyethylated alkyl phenol as said oxyethylated alkylphenol with degree of oxyethylation of 12 and additionally—PAA and isopropyl alcohol—IPA. Ratio of components in water fringe, wt %: PAA—0.1–0.15, IPA—0.5–2.0, nonionic surfactant—0.3–0.5, water—balance. Wherein said composition is an aqueous solution and trimmed mixture is injected in a volume ratio of 1: 1 to 1:12, is then forced into the water reservoir in volume of 10–20 m³ and the well is left for technological exposure for up to 5 days.

EFFECT: technical result consists in reduction of permeability of high-permeability zones of formation by increasing filtration resistance, improving strength properties of injected gel-forming compositions, involving in development of low-permeable, previously unreached oil-saturated interlayers, which increases efficiency of formation coverage by impact and increased oil recovery of formations, which allows expanding technological capabilities of the method.

1 cl, 2 dwg, 1 ex