With controls on the disposal of produced water getting ever stricter and the specification for produced water injection getting ever tighter, the focus on produced water treatment is increasing and optimisation of existing separation performance and chemical dosing can significantly increase the efficiency of the produced water treatment process at very low cost. Historically, this type of work is conducted by laboratory testing such as oil in water analysis by solvent extraction and extensive bottle testing for chemical compatibility. These laboratory tests are very useful and provide important process information; however, they are very labour-intensive and can take weeks to accomplish.
Jorin’s Process Insight is an on-site service that produces excellent results in a fraction of the time.
The Jorin Process Insight team uses ViPA instruments, an online video microscope system that provides real-time online data on oil and solids concentrations and particle sizes simultaneously. This allows equipment and chemical optimisation to be conducted in hours or days rather than weeks.
During recent field work with a client, two ViPA units were set up on the inlet and the outlet of the production hydrocyclone. As the ViPA units provide information on the size and concentration of the oil droplets it was used to calculate the real-time efficiency of the hydrocyclone. The size distribution data obtained showed that the liners were not working effectively due to the inlet droplet sizes being out with the manufacturer’s specification.
A series of trials for the selection and dosing rate of a demulsifier were carried out to determine if the droplet sizes on the inlet could be increased to allow the hydrocyclones to work better. After these trials the data obtained allowed for a selection of the best performing demulsifier chemical. Further work was then conducted to select the optimum dose rate for the new demulsifier.
At an injection rate of 8ppm poor process control was observed, with the interface level in the production separator being very hard to maintain. At the rate of 10ppm this problem was alleviated and a better BS&W was also achieved. The demulsifier dose rate of 10ppm was selected and proved to be ideal for both better process control and achieving the desired hydrocyclone efficiency.
The real-time data obtained allowed hydrocyclone and chemical optimisation to be carried out in days rather than weeks while maintaining acceptable BS&W. A total of 20 chemical dosing regimes were trialled within eight days. This reduction in trial duration and manpower deployed freed up the limited bed space offshore, reducing both costs and risks to personnel; enabling better separation to be achieved, the disposal specification to be met and by optimising chemical dose rate, production costs to be reduced.
For further information please contact Nick Roth, Jorin (tel: +44 116 275 3300, fax: +44 116 275 3322 or email: [email protected]) or visit Jorin’s website.