METHOD OF PREVENTING FORMATION OF IRON SULPHIDE WHEN MIXING DEVONIAN AND CARBONIFEROUS LIQUIDS Russian patent published in 2025 - IPC E21B37/06 C09K8/528 

FIELD: oil industry.

SUBSTANCE: invention relates to oil industry and specifically to methods of preventing formation of iron sulphide in wells with simultaneous separate operation, field oil-gathering system in which mixing of well products – Devonian and Carboniferous liquids – takes place. Method of preventing formation of iron sulphide when mixing Devonian and Carboniferous liquids includes treating the Devonian liquid with a phosphorus-containing reagent based on nitrilotrimethylphosphonic acid with additives and then mixing with the Carboniferous liquid. Said reagent contains, wt.%: nitrilotrimethylphosphonic acid 16.5-17.0; 25% aqueous ammonia solution 6.0; monoethanolamine 2-2.5; methanol 35-38; water is the rest, wherein an aqueous solution of nitrilotrimethylphosphonic acid is first prepared, to which 25% aqueous ammonia solution, monoethanolamine and methanol are successively added while stirring constantly.

EFFECT: improving stability of pumped reagent, including at low ambient temperature; preventing formation of iron sulphide in oil, which is formed at mixing of Devonian and Carboniferous liquids; reducing stability of water-oil emulsions.

1 cl, 1 tbl, 1 ex