FIELD: oil and gas producing industry; applicable, particularly, in determination of salt deposition in wells in the course of their operation in development of gas and gas-condensate deposits. SUBSTANCE: method of determination of salt deposition in mixing of formation waters with service fluids includes sampling of formation water, preparation of its blends with service life fluid and judgement on salt deposition. In so doing, content of basic ions in formation water and then in service fluids and in their blends is determined. Actual and theoretical ionic and salt compositions of blends are calculated. Then calculations of actual and theoretical salt compositions are compared and amount of each salt fell-out of each blend is calculated. EFFECT: increased service life of well and oil field equipment. 4 tbl
