“The mobile evaporator increases Cabot Specialty Fluids’s recycling capability”, says Malcolm Cook, Regional Manager at Cabot Specialty Fluids, shown here with the unit before shipment to Kazakhstan
Cabot Specialty Fluids improves its ability to re-densify cesium formate in remote locations with its newly commissioned mobile evaporator. The mobile evaporator is currently on location in Kazakhstan where Cabot is contracted to supply cesium formate brine for HPHT wells in the vast Kashagan oil field.
Delivering and maintaining correct density is essential for any completion operation using any brine. As water contamination often dilutes the brine, density adjustments must be made regularly when the brine is used in multiple wells. Increases are achieved by adding cesium formate powder or high-density ‘spike’, or through water evaporation. Often, the scale of operation and degree of contamination dictate the optimum process.
In North Sea offshore operations, brine is normally shipped back to one of Cabot’s reclamation centres for treatment. In Kazakhstan, the brine can now be redensified on site with the mobile evaporator – a principle that can be applied to most remote offshore or onshore fields to increase operational effectiveness. The unit’s strong metal frame, similar in size to a 20-foot ISO container and certified to DNV CN2.7-1, means the mobile evaporator is easily lifted and transported to its next assignment.
Malcolm Cook, Regional Manager, explains how the mobile evaporator works: “The unit operates under a partial vacuum, which both drives the process and reduces the boiling temperature of cesium formate. Dilute cesium formate is sucked into the evaporator and passed through a heat exchanger, where it exchanges heat with the refined cesium formate leaving the system. It then enters a continuous circulating loop where an immersion heater further raises the diluted brine’s temperature until the boiling point is reached and water ‘flashes off’ as vapour into a separator pot. The water vapour is pulled by the vacuum through air blast condensers and pumped out of the system. This process continues until the cesium formate reaches its designated weight and is also pumped out. When this happens more dilute brine is drawn in and the process continues automatically.”