METHOD OF HYDRAULIC FRACTURING OF LOW-PERMEABLE FORMATION OF INJECTION WELL Russian patent published in 2012 - IPC E21B43/26 

FIELD: oil and gas production.

SUBSTANCE: method includes pumping of hydraulic fracturing fluid into formation through the well via tubing with packer with viscosity not less than 0.01 Pa·s with the following pumping of hydraulic mixture with proppant. Hydraulic fracturing is done by intervals from the top downwards in each interlayer of formation with the use of two packers mounted above and below the formation interval specified for hydraulic fracturing. Each adsorbing interlayer of formation is pumped via tubing by hydraulic fracturing fluid under pressure twice exceeding the injection capacity of formation for 3-4 hours. The above operations are repeated depending upon the quantity of formation adsorbing interlayers. The packing of all adsorbing interlayers of formation is done by pumping hydraulic mixture with proppant via tubing by installation of blind packer under the lower adsorbing interlayer and through packer in tubing over the upper interlayer of formation, the hydraulic mixture - lime slurry - is pumped into the well from 3 to 6 m³ in concentration 20 kg of CaO per 1 m of water with the following adding of spent sulphite liquor in ratio from 1:0.2 to 1:0.4 with viscosity 450-500-10^-3 Pa·s. After that the injection well is put into operation. As working agent pumped into injection well there used is water of 1000-1180 kg/m density not containing suspended solid particles and ferrous hydroxide.

EFFECT: increase of method efficiency not depending upon interlayer injection capacity and speed of hydraulic fracturing fluid pumping into formation as well as the possibility to perform repetitive operations on formation injection capacity restoration.

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