METHOD FOR CONTROLLING THE PERMEABILITY OF A HETEROGENEOUS OIL STRATUM

摘要

The invention relates to the oil and gas extraction industry, in particular to methods for expelling unrecovered oil, said methods reducing the permeability of flooded strata, drawing oil‑saturated sections of low permeability into development and increasing oil recovery. The technical result of the invention consists in creating an effective method for controlling the permeability of a heterogeneous oil stratum by reducing the permeability of zones of high permeability of a water‑saturated reservoir. The method for controlling the permeability of a heterogeneous oil stratum comprises pumping an aqueous suspension of sludge into the stratum – the sludge being a waste product of the production of sodium carbonate from Dorr settling tanks between separating banks of fresh water, pressing said sludge through together with the bank of fresh water in a volume equal to the volume of the above‑mentioned suspension and shutting the well down for 24 hours. As the above‑mentioned aqueous suspension of sludge – a waste product from the production of sodium carbonate from Dorr settling tanks, use is made of a sludge from the final production stage having the following composition, g/l: calcium carbonate – 80.0-90.0, calcium hydroxide – 2.0-10.0, magnesium hydroxide – 4.0-5.0, calcium sulphate – 0.4-0.6, sodium chloride - 300, sodium hydroxide – 2.0, the remainder comprising impurities and water. Mineralized waste water with a density of 1.107 g/cm3 is additionally pumped in.