Prediction of the Deposition of Sulfate Salts Taking the Content of Strontium during the Exploitation of Oil Fields into Account

Resumo

Based on the experience of developing an oil field on the Caspian Sea shelf, which was initially exploited with injection of seawater into the oil-bearing beds to maintain reservoir pressure, the deposition of sulfate salts under reservoir conditions is predicted. The prediction of sulfate deposition is made in two ways: analytical calculations according to the method of J.E. Oddo and M.B. Thomson and computer modeling. The prediction took the strontium content in the formation waters of the oil-field into account, which is usually ignored in production practice. It has been established that the prediction by computer modeling is more accurate; in particular, it considerably expands the temperature limits of anhydrite precipitation. The amount of potentially precipitable sulfate salts found by computer modeling has shown that the mass of deposited calcium and strontium sulfates is rather large, which can significantly reduce the permeability of the reservoir.