METHOD OF WELL SHAFT CLEANING FROM DRILLING MUD FILTER CAKE Russian patent published in 2025 - IPC E21B43/27 C09K8/528 

FIELD: mining.

SUBSTANCE: invention relates to the oil and gas industry, specifically to methods for treating the bottom-hole zone of a wellbore before oil or gas production in order to remove the polymer-carbonate filter cake formed when filtering a drilling biopolymer mud when drilling an open-hole well, and can be used in fields where drilling and opening of productive formations is carried out on clay-free weighted drilling fluids. Method of cleaning a wellbore from a filtration cake of a drilling mud comprises injecting and holding in wellbore for 24–72 hours a composition containing, wt.%: ammonium fluoride peroxo-solvate 0.5–10, triethanolamine 0.01–5.0, water is the rest. Said composition contains a peroxo-solvate of ammonium fluoride with concentration of hydrogen peroxide in an amount of more than 45 wt.%.

EFFECT: increased range of formation temperatures from 15 °C to 120 °C, at which the effective removal of the filtration cake of the drilling mud and increase in the recovery factor of the permeability of the bottomhole zone of the well are provided.

8 cl, 2 tbl, 3 ex