The Development of a 'Green' Hydrothermally Stable Scale Inhibitor for Topside and Squeeze Treatment

Concern for the environment has lead to legislation that is driving the use of chemicals in the off shore North Sea oil industry. The increased awareness and scrutiny of the impact of chemical discharge on the environment is likely to ensure adoption of these or similar policies on a global basis. The need for low toxicity, biodegradable and hydrothermally stable scale inhibitors is increasing and greener chemistries are being sought to meet these challenges. This paper describes a barium sulphate and calcium carbonate scale inhibitor that meets low toxicity requirements and the present Norwegian ‘Y1’ criteria for biodegradation. Dynamic scale loop tests are used to evaluate the inhibitor compared to a commercial ‘green’ inhibitor for carbonate and sulphate scales. Hydrothermal studies performed under differing pH regimens demonstrate stability to 180°C and a marginal drop in performance at 200°C thereby showing good potential for squeeze treatment under HPHT conditions in addition to topside application.

Keywords: Scale inhibitor, calcium carbonate, barium sulphate, jar test, dynamic scale loop, water chemistry, hydrothermal stability, squeeze treatment.