WELL BOTTOM ZONE TREATMENT METHOD Russian patent published in 2006 - IPC E21B43/27 

FIELD: oil industry, particularly methods for stimulating production.

SUBSTANCE: method involves forcing solution of acid and surfactant in productive formation zone; exercising technological time-delay and providing differential pressure drawdown. The solution is obtained by solving surfactant, namely chromium acetate-based surfactant, heated up to 80-90°C and highly concentrated hydrochloric acid in distillated water to reduce hydrochloric acid concentration up to 5-20%. The solution is injected at temperature of 30-70°C. Volume of the solution is enough to heat flow string to temperature providing mudding member melting, that is not less than 0.8 m³/m of productive formation. The solution if formed by light-weight oil having flow rate of 24-35 m³/day under initial pressure of 0.8-1.5 MPa at flow string head. The time delay is carried out for not more than 2 hours. Differential pressure drawdown is performed by swabbing operation when hole annuity is packed to obtain well bottom pressure drawdown of not less than 3 MPa.

EFFECT: increased efficiency of well bottom zone treatment.

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