METHOD FOR KILLING WELLS WITH ABNORMALLY LOW FORMATION PRESSURE USING FLUIDS FOR HYDRAULIC FRACTURING Russian patent published in 2025 - IPC E21B43/26 C09K8/62 E21B43/12 

FIELD: obtaining oil and gas from wells.

SUBSTANCE: invention relates to oil and gas industry, in particular to methods of well killing and conservation, to methods of preparing and using fluids for hydraulic fracturing, and can be used to limit water influx into oil and gas wells. Method involves preparation of foaming solution containing 0.0075 wt.% of biocide of aqueous gels "РГУ Био ВГ", 0.3-0.6 wt.% of a polysaccharide thickener, in form of a gelling agent of water gels "РГУ ГВГ" of grade C, 0.1-0.25 wt.% of xanthan thickener E415 as xanthan polymer, 0.5-1.5 wt.% of foaming agent "РГУ НГ МГС" of RL grade, fresh or mineralized water, which mainly contains monovalent cations – the rest. Prepared foaming solution is fed into the well together with gas, which is nitrogen from nitrogen plant, in volume ratio under normal conditions of foaming solution : nitrogen, equal to 1:1-10, respectively. Foaming solution and nitrogen are supplied through the first T-piece, and the obtained foam is supplied through the second T-piece, where the cross-linking solution is simultaneously supplied at a volume ratio of the foam-forming solution : the cross-linking solution equal to 4:1, respectively. Cross-linking solution contains 1.0-2.0 wt.% of boric cross-linking agent "РГУ СБВГ" of grade 10, 0.0-50.0 wt.% of diethanolamine and fresh or mineralized water – the rest.

EFFECT: increasing the efficiency of the method of killing wells with abnormally low formation pressure by increasing the stability of the foam used, preventing its absorption in such wells for their faster development after repair work.

1 cl, 1 tbl, 4 ex