METHOD TO REDUCE FORMATION OIL VISCOSITY ANOMALIES Russian patent published in 2019 - IPC E21B43/20 E21B28/00 

FIELD: oil and gas industry.

SUBSTANCE: invention relates to oil industry and can be used for development of deposits of abnormal (non-Newtonian) oil using flooding. Method comprises drilling horizontal injection wells and production wells at ratio of 1:2, horizontal sections of which are parallel to each other in a horizontal plane along natural fracturing lines, model of formation water injection into horizontal injection well and fluid extraction from horizontal production well, periodic treatment of horizontal section of injection well by physical exposure at frequency of 1 time in 5–7 months. According to the invention, after development of average water cut of the well product by production wells at the developed operational facility up to 45 %, three modes of development of oil deposit with abnormal (non-Newtonian) oil are alternately used. First mode involves pumping of formation water model through injection wells with content of non-ionic surfactant – reagent OP-10 – in amount of 0.05–0.15 wt% in volume up to 0.5 (inclusive) of pore volumes of hydrodynamically connected channels of productive formation or with content of sodium hydroxide in amount of 0.10–5.00 wt% in volume of 0.1–0.2 of pore volume of hydrodynamically connected channels of productive formation. Either 95 % of hydraulic fracturing pressure is reached before reaching bottom-hole pressure. Second mode includes treatment of productive interval of formation of horizontal production well by physical action – device for generation of elastic resonance pulses in hydrosphere of horizontal well – and maintenance for process pause of up to 30 hours for redistribution of filtration flows and reduction of oil viscosity anomalies due to dispersing action of main structure-forming components of oil – asphaltenes. Third mode involves injection of formation water model containing polyacrylamide in amount of 0.03–0.15 wt% through injection wells in volume up to 0.5 (inclusive) of pore volumes of hydrodynamically connected channels of productive formation. Either 95 % of hydraulic fracturing pressure is reached before reaching bottom-hole pressure.

EFFECT: technical result is higher efficiency of displacement of abnormal (non-Newtonian) oil from formation.

1 cl, 2 dwg