Forecast of the deposition of sulfate salts, taking into account the content of strontium, in the exploitation of oil deposits

Abstract

Based on the experience of developing an oil fieled on the Caspian Sea shelf, which was initially operated with injection of seawater into oil-bearing seams to maintain reservoir pressure, a forecast was made for the deposition of sulfate salts in reservoir conditions. The forecast of sulphate deposition is carried out in two ways: analytical calculations by the method of J.E. Oddo and M.B. Thomson and computer modeling. The prognosis took into account the strontium content in the reservoir waters of the deposit, which is usually ignored in oilfield practice. It has been established that computer modeling gives a more accurate prediction, in particular, considerably expands the temperature limits of anhydrite precipitation. The determination of the amount of potentially sulphate salts potentially found in computer simulations has shown that the mass of deposited calcium and strontium sulfates is large enough that it can significantly reduce the permeability of the reservoir.