METHOD FOR PREPARATION OF FORMATION WATER TO MAINTAIN FORMATION PRESSURE AND METHOD FOR MAINTAINING OIL POOL FORMATION PRESSURE Russian patent published in 2017 - IPC E21B43/20 C02F1/20 C02F1/52 C02F1/64 C02F9/02 C02F101/10 C02F103/06 

FIELD: oil and gas industry.

SUBSTANCE: method for preparing formation water for the Devonian oil pool formation preassure maintenance system and/or lower carbon pool and middle and/or upper carbon pools contain stages, when: oil-gas-water mixture is extracted -OGWM from the Devonian and/or lower carbon pools as well as middle and/or upper carbon pool, perform oil extraction from said OGWM, recover oil thereof. In the result the obtained Devonian and/or lower carbon pool formation water, containing ferrous ions, is mixed with the middle and/or upper carbon pool formation water, obtained in the result of it, containing hydrogen sulfide. At least one coagulant is added in mixed formation water for consolidation of fine particles of iron sulfide, formed in the result of said mixing, perform cleaning of mixed formation water from iron sulfide and feed cleaned formation water mixture to said system for maintainig formation preassure to inject into pressure wells, operating the Devonian and/or lower carbon pools as well as middle and/or upper carbon pools. The method for maintaining the formation pressure of the Devonian and/or lower carbon pools and the middle and/or upper carbon pools comprises a step for injecting the formation water prepared by said method into pressure wells, operating the Devonian and/or lower carbon pools as well as middle and/or upper carbon pools. The invention has been developed in the dependent claims.

EFFECT: provide the possibility of joint preparation for formation water from the Devonian and carbon pools to maintain pressure in said pools.

10 cl, 2 dwg, 1tbl