METHOD OF WATER INFLUX ISOLATION IN WELL Russian patent published in 2019 - IPC E21B33/138 E21B43/22 C09K8/512 

FIELD: oil and gas industry.

SUBSTANCE: invention relates to oil and gas industry, in particular, to methods of limiting water influx in flooded reservoirs. Method involves pumping into the formation a gel-forming composition containing a water-soluble polyacrylamide polymer – PAA, chromium acetate and water. That is combined with successive pumping of a gel-forming composition based on PAA with high molecular weight and a gel-forming composition based on PAA with low molecular weight. High-molecular weight PAA-based gel-forming composition contains 0.3–0.5 pts. wt. PAA with molecular weight of 5–12 million amu, 0.15–0.20 pts. wt. chromium acetate, 100 pts. wt. water. Low-molecular-weight PAA-based gel-forming composition contains 1.7–4 pts. wt. PAA with molecular weight of 1–2.5 million amu, 0.15–0.6 pts. wt. chromium acetate and 100 pts. wt. water. Volume of the gel-forming composition based on PAA with high molecular weight is 75–85 %, and the gel-forming composition based on PAA with low molecular weight – 15–25 % of the total volume of pumped gel-forming compositions.

EFFECT: technical result is higher efficiency of isolation of water influx and longer duration of effect of using method due to use of homogeneous homogeneous gel-forming composition with good filtration properties and formation of a strong polymer gel directly in the zone of water influx isolation, as well as increase in the insulating polymer gel resistance to pressure drops.

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