An offshore installation on the Norwegian continental shelf produces crude oil from both platform wells and subsea satellite wells. The addition of several new wells altered the oil composition, which had a negative effect on the performance of the demulsifier used. The product could not drop water out of the crude oil fast enough in the first-stage separator, causing overloading in the subsequent stage. A new demulsifier was required to deliver drier crude to the second stage. The operator also wanted to reduce the amount of oil in produced water to improve economics as well as satisfy the stringent regulatory requirements.
The platform wells produce oil with high asphaltene content, high TAN, or both, while the two subsea satellites produce crude containing wax and asphaltenes. Identifying one demulsifier to perform satisfactorily with all the various crudes was a challenge.
SLB performed a bottle test on site and identified several raw materials that could help. After conducting full-scale tests on the system, a final combination of raw materials was selected and formulated into a new demulsifier EB-82116. This new product was subsequently tested on the installation for a month. Average WIO fell to 0.33% by injecting 8.5 ppm of EB-82116, compared with 0.44% with 18 ppm of the original product. Oil in produced water decreased to 16 mg/L from 34 mg/L, a 53% reduction. More cost effective and robust, the new product is helping the operator avoid having to shut in wells because of excessive WIO or oil in water (OIW).
