METHOD TO CONTROL INJECTION WELL INJECTIVITY PROFILE Russian patent published in 2008 - IPC E21B43/22 

FIELD: oil field development, particularly to increase oil recovery from flooded oil reservoirs with non-uniform permeability by control of injection well injectivity profile.

SUBSTANCE: method involves preparing silica gel; metering and mixing thereof with water to be injected from water conduit and injecting the obtained silica gel suspension in well. First of all initial injection well injectivity is determined. Silica gel is prepared by simultaneous mixing of dilute hydrochloric acid and sodium silicate solution jets in conveyer screw provided with variable speed drive, wherein the solutions are taken in proportion from 1:1 to 1:2. Rate of said solutions is regulated by change of variable speed drive index in dependence of solution concentration. Diluted solution concentrations and ratio thereof is carried out to provide rapid gel forming during component mixing. Silica gel is milled in conveyer screw to obtain gel particles of 0.01-0.5 mm dimensions. Gel is added to water to provide 0.05-75% by weight concentration. Injection is carried out in dependence of initial well injectivity beginning from minimal suspension concentration under minimal injection pressure with gradual concentration increase up to admissible value of pressure acting on production string with following pressure value maintenance due to suspension concentration reduction.

EFFECT: increased efficiency due to control of composition components mixing and regulation of silicate gel H-factor stability, increased gel suspension filtering ability index and extended functional capabilities of method realization.

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