METHOD FOR THERMO-CHEMICAL TREATMENT OF OIL RESERVOIR Russian patent published in 2020 - IPC E21B43/22 C09K8/58 

FIELD: oil and gas industry.

SUBSTANCE: invention relates to oil industry, in particular, to methods for thermo-chemical treatment of oil reservoir. Proposed method comprises simultaneous or sequential pumping of two aqueous solutions representing thermochemical composition in volume ratio of 1:1. First aqueous solution contains components, wt%: ammonium nitrate – 30–40, sulphamic acid – 8–12, ammonium bicarbonate – 5–10, fresh water – the rest, the second one – sodium nitrite with concentration of 40–45 wt%. After pumping of aqueous solutions there performed is successive pumping of acid composition containing inhibited hydrochloric acid with concentration of 60 wt%, sulfamic acid – 2 wt%, ammonium acetate – 3 wt%, neonol AF9-12 – 0.15 wt% fresh water – balance, and high-viscosity polymer composition. High-viscous polymer composition contains the following components, wt%: polyacrylamide – 0.1–0.6, 10 % solution of chromium potassium alum – 0.1–0.6, fresh water – balance. Thermochemical composition, acid composition and high-viscosity polymer composition is pumped in volume ratio 1:(0.5–2):(0.5–1), they are pumped into the formation by water, the well is stopped for process exposure for 4 hours and flooding is resumed. For highly-receiving wells prior to thermochemical composition pumping highly-viscous polymer composition is injected at their volume ratio of 1:(1–3).

EFFECT: increased coverage of formation by action and connection of low-permeable oil-saturated interlayers increases oil recovery, reduced water content of extracted products.

1 cl, 3 tbl