Concern for the environment has led 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, adsorption, squeeze treatment.