FIELD: oil-and-gas production.
SUBSTANCE: invention related to a method of calcium content decrease in fluid hydrocarbon medium, which includes contacting of mentioned above fluid hydrocarbon medium with a sequestrant, represented with a carboxylic acid for calcium containing separating complex formation, b. contacting of mentioned above fluid hydrocarbon medium with water medium for emulsion formation, in which after the mentioned above emulsion separation, at least part of the mentioned separated calcium containing complex stays in the water medium, and contacting the mentioned water medium with water soluble or water dispersing polymer, with I formula for the calcium disposals inhibition on surfaces, contacting with the mentioned above water medium, where the polymer has: 
(I) formula, where E - is a repeating fragment, which remains after non-saturated ethylene type compound polymerization, R1 is a hydrogen atom or the lowest (C1-C6)- alkyl or carbonyl, Q - is O or NH, R2 - is the lowest (C1-C6)-alkyl, hydroxy - substituted the lowest (C1-C6)-alkyl, the lowest (C1-C6)-alkyl sulfonic acid -(Et-O)-n, -(iPr-O)-n or -(Pr-O-)n, where n - is a variable from around 1 up to 100, and R3 - is a hydrogen atom or XZ, where X - is anion radical, selected form a group, consisting from SO3, PO3 or COO, Z - is hydrogen atom or atoms or any other water soluble cationic fragment, which serves is a balance in X anion radical valence; F - when presented, is a repeating fragment with a II: 
formula, where X and Z are the sane as in I formula, R4 - is a hydrogen atom or (C1-C6) the lowest alkyl, R5 - is hydroxy - substituted alkyl or alkylene, which has from 1 to 6 atoms, and XZ can or can not to be presented, c and d - are positive whole numbers, e is not-negative number, and j is equal to 0 or 1.
EFFECT: calcium disposal decrease on a surfaces contacting with water phase water in oil separated emulsion.
21 cl, 7 ex, 7 tbl
