METHOD OF CLEANING BOTTOMHOLE FORMATION ZONE FROM CLAY FORMATIONS Russian patent published in 2019 - IPC E21B37/06 C09K8/52 E21B43/22 

FIELD: oil and gas industry.

SUBSTANCE: invention relates to the oil and gas industry. In the method of cleaning the bottomhole formation zone (BFZ) the loose part of clay formations is removed from clay formations by washing the BFZ with technical water, after which a water-based cleaning reagent is pumped into the BFZ and the above reagent is maintained until the dense part of the clay formations are destroyed. Volume of water-based cleaning reagent is chosen so that the height of the liquid column of the injected water-based cleaning reagent is higher than the top of the productive formation. Carry out the washing of the reaction products, pumped into the BFZ aqueous acid solution and maintain the above solution for the time required to dissolve the residual clay formations. Then well is developed. Water-based cleaning reagent contains hydroxylamine hydrochloric acid in the amount of 12–14 wt. % and quinhydrone in the amount of 0.1–0.3 wt. %, and the aqueous acid solution contains nitrilotrimethylphosphonic acid in the amount of 9–11 wt. %.

EFFECT: increased efficiency of cleaning the BFZ from clay formations.

1 cl, 1 tbl