CaCO3 scale prevention by additives in the presence of heavy metal ions

• Q. Wang, H. AlSaiari, F. AlDawood and M. AlDossary

Saudi Aramco, Research and Development Center, Dhahran, 31311, Saudi Arabia

Abstract: Formation of calcium carbonate (CaCO3) deposition is a common problem during hydrocarbon production process. Effective scale management is important to maintain field productivity and profitability. Use of threshold scale inhibitor has been the most cost effective approach to control CaCO3 deposition. The performance of scale inhibitors is determined by many factors such as calcium and bicarbonate concentrations, pH, temperature, suspended solids. This article presents the influences of three heavy metal ions, Cu²⁺, Ni²⁺, and Zn²⁺, on the performance of phosphonate and polymeric inhibitors against CaCO3 precipitation and deposition in synthetic oilfield brine. It is shown that even at 2 to 5 mg/L, heavy metal ions can have a significant impact on phosphonate inhibitors. The inhibition efficiency of tri-phosphonate is improved by Cu²⁺ ions but reduced by Zn²⁺ ions, and the performance of penta-phosphonate is enhanced by Cu²⁺ and Zn²⁺ ions and deteriorated by Ni²⁺ ions. Polymeric inhibitor is less affected by these heavy metal ions and no antagonistic effect is observed. The results presented herein are important in the development of cost-effective CaCO3 prevention programs and development of new mitigation methods.

Keywords: oilfield scale, calcium carbonate, scale inhibitor, heavy metal ions.

Int. J. Corros. Scale Inhib., 2016, 5, no. 1, 12–30 PDF (1 532 K)
doi: 10.17675/2305-6894-2016-5-1-2

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