Customized pour point depressant enables subsea flow of waxy crude

The custom-engineered product PI-7096 enabled crude oil flow despite significant wax content, low subsea temperatures, and pump limitations, hence preserving field economics.

Analysis of well fluid samples from a subsea oil field on the Norwegian continental shelf indicated that the pour point of the waxy crude oil—the lowest temperature at which oil can flow without assistance—was 27 degC [81 degF]. Subsea temperatures offshore Norway are far lower. Consequently, to produce the oil via a subsea pipeline, a pour point depressant is required that is

• stable at subsea temperatures
• able to reduce the pour point below these temperatures
• effective at an injection rate of 800–1,000 ppm because of limitations of the injection pump.

SLB tested several products, and the most effective raw material was formulated into PI-7096, a proprietary pour point depressant based on a dendritic wax inhibitor. PI-7096 is 10 times more active than conventional products without becoming too viscous or gelling. Laboratory tests showed that injecting PI-7096 at 1,000 ppm reduced the pour point to 9 degC [48 degF]. The product was injected into the crude at a rate of 800 ppm, and oil is flowing without any issues.