Northshore CC8290: Desalting across changing crude slates

The refinery experienced inconsistent emulsion separation as its crude slate and unit load changed. A crude slate is the mix of crude oils entering the refinery; changes in that mix were therefore part of the operating challenge. The team needed a program that could respond to feed variability while keeping the desalter's oil and water outlets under control.

The project evaluated two targets together: less than 3 mg/L salt in desalted crude and less than 400 mg/L oil in desalter effluent water. This gave the refinery a practical view of separation performance on both sides of the interface. Lower salt in the crude was one objective, while limiting oil carried into the effluent was another. The treatment needed to support both, within the refinery's operating conditions.

Northshore CC8290 is Cestoil's oil-soluble, water-dispersible demulsifier. The refinery applied it through automated dosing equipment on two crude lines. Treatment rates were selected in relation to emulsion severity and salt content, with wash-water conditions assessed as part of the same program.

The product's field evaluation therefore went beyond selecting a chemical and leaving the feed rate unchanged. The refinery and service team used the measured separation response to assess whether the treatment remained appropriate. That approach is particularly relevant where a plant processes a changing crude slate and needs the demulsifier program to follow the behavior of the incoming feed.

During the two-month evaluation, engineers monitored desalting performance and adjusted chemical injection and wash-water ratios. The source account treats these interventions as part of the program that produced the result. Their contribution belongs in the case history because it explains how treatment was managed under variable operating conditions.

For a comparable refinery, a crude-slate change should trigger a review of incoming crude quality, emulsion behavior and the desalter's response. Service personnel and operators can then decide whether a chemical-feed adjustment, an operating adjustment or further observation is needed. A different crude slate does not automatically call for more chemical; it calls for reassessment based on the actual separation performance.

The monitoring approach connected incoming crude conditions with salt in desalted crude and oil in the effluent water. Unit load, chemical feed and wash-water records provide the context for interpreting those results. Aligned samples help the operating team understand which incoming conditions and treatment settings belong to each observed outcome.

This is useful when incoming salt content varies. A stable desalted-crude result can indicate effective control, but the effluent-water result is still needed to judge the wider separation outcome. Following both indicators helps avoid a narrow assessment based on one favorable sample or one outlet stream. It also gives the service team a clearer basis for verifying whether an adjustment has improved the program.

The central lesson is the connection between demulsifier selection, field service and measured separation performance. A refinery with changing crude slates can use this case to frame a trial around its own feed variability and its own crude-salt and effluent-water targets. That makes the evaluation relevant to daily operation rather than only to a laboratory comparison.

Before starting, assemble representative crude-quality records, processing-load changes, wash-water conditions and aligned samples from the desalter outlets. Track chemical consumption alongside those measures. Any economic comparison should use equivalent throughput and crude conditions and include the cost of both chemical and service. The existing summary reports operating performance, with no quantified monetary saving, so financial value should be established from the new site's records.