METHOD FOR INCREASING OIL RECOVERY FROM A CARBONACEOUS OIL FORMATION BY BUILDING UP FORMATION PRESSURE

摘要

A method comprises selecting a well with a current formation pressure of a maximum of 0.6·Р, wherein the operations are carried out in two stages. In the first stage, a working fluid – water with a total salinity of 0.8-1.2 of the total salinity of the formation water – is injected into the well, injection being carried out until the well-head pressure increases to a value of a maximum of 0.2·Ρ, then a 1-10% solution of a surfactant in the working fluid is injected under a well-head pressure of (0.2-0.4)·Ρ, after which working fluid is again injected until the well-head pressure increases to 0.4·Ρ. Soaking is carried out for a maximum of 48 hours. If the well-head pressure drops, working fluid is injected until the pressure increases to 0.4·Ρ. In the second stage, a complex acid composition is injected with the addition of surfactant, water, acid-rock reaction retarders, clay stabilisers, and reagents for producing self-deflecting acid compositions and/or acid emulsions depending on the filtration properties of the formation. Injection is carried out with a well-head pressure of a maximum of 0.45·Р, and the complex acid composition is driven by working fluid at a well-head pressure of a maximum of 0.45·Р. Soaking is carried out for a maximum of 24 hours.