As a result of
waterflooding, inorganic salt precipitation occurs in the different parts of an
oil production system, thereby leading to damage of production equipment.
Different parameters affect the kinetics of salt precipitation. Scale
inhibitors are widely used to prevent inorganic salt formation. In this study,
the effect of reservoir pressure, temperature, and mixing ratio of injection to
formation water on calcium sulfate and barium sulfate precipitation was
investigated. For this purpose, two different formation waters and one
injection water were used. In addition, the effect of temperature and mixing
ratio on inhibition performance was studied. Four different existing industrial
scale inhibitors and one new scale inhibitor were used. The performance of the
scale inhibitors was determined under static and dynamic conditions. Results of
the study showed that calcium sulfate precipitation increased with an increase
in temperature and a decrease in pressure. Barium sulfate precipitation was
found to increase with a decrease in the temperature. The effect of pressure on
barium sulfate formation was negligible. The developed scale inhibitor showed
the highest performance for the prevention of calcium sulfate and barium
sulfate formation. A change in temperature from 60°C to 120°C reduced the
inhibitor performance by 3%. In the cases of calcium sulfate and barium
sulfate, the minimum performance of the scale inhibitor was observed when the
mixing ratios of injection to formation waters were 60:40 and 50:50,
respectively.
