On an offshore installation on the Norwegian continental shelf, produced fluids enter the first-stage oil-water separator. The output water passes through hydrocyclones and a degasser for additional cleaning before it is discharged overboard. The oil exiting these units as “reject streams” is mixed with the crude oil leaving the first separator to enter a second one, followed by an electrostatic coalescer that reduces WIO to levels suitable for export.
However, the operator was encountering a challenging emulsion layer in the second-stage separator. Inability to destabilize this interfacial layer hindered separation of oil and water, resulting in high levels of WIO and OIW at the output, which were challenging subsequent processing. Reemulsification of the reject streams entering the second separator was identified as the likely cause of the issue. The operator turned to SLB for a tailored demulsifier that could minimize this effect.
The SLB production chemistry team identified two chemicals that have been shown to reduce reemulsification. A base product was formulated through a bottle test and taken offshore together with the two chemicals. The base product was first injected alone and subsequently after mixing it with each of the chemicals in turn. The combination that yielded optimal results was formulated into the proprietary demulsifier EB-80101.
Deploying the new demulsifier eliminated buildup of the interfacial layer in the second-stage separator and reduced both OIW and WIO by 50%.
