METHOD FOR COLMATAGE REMOVAL FROM BOTTOMHOLE FORMATION ZONE UPON FIRST OPENING TO RESTORE PERMEABILITY AND POROSITY OF HEADER Russian patent published in 2015 - IPC E21B43/27 E21B37/06 C09K8/74 

FIELD: oil and gas industry.

SUBSTANCE: in the method acid process composition is injected to the well, withheld for reaction with further removal of reaction products from the formation. Before injection of the acid process composition, upon the last running in of tool for washing of the borehole before development a mixture of non-ionic surfactant with sulphamic acid at mass ratio of 0.003-0.005:1 in quantity of 1-3 wt % is introduced to drill mud containing high-molecular compounds and colmatant used for opening and washing of the producing formation. Then, upon the last running out of tool from the well and running in of tubing string the above drill mud is replaced by the acid process composition and the latter is withheld for reaction during at least four hours. The acid process composition consists of the following ingredients, by wt %: peroxide compound 0.5-3.0; sulphamic acid 5.0-10.0; non-ionic surfactant 0.005-0.02; mineralized water takes the remaining share. Density of the above process composition is equal to density of the drill mud used at opening of the producing formation or differs from it less than per 10%.

EFFECT: improved efficiency and producibility of colmatage removal from the bottomhole zone of the producer borehole, including inclined and horizontal wells, upon usage of the process fluid containing high-molecular compounds and colmatants.

7 cl, 4 tbl, 2 ex