Case Study: Nexen Scott

Denholm MacNamee were tasked with decontamination of the Telford Separator on the Scott platform. This unit contained significant sludge levels and high levels of H2S and LEL.


A chemical decontamination procedure was implemented using an aqueous ZymeFlow® UN657 solution.  ZymeFlow® UN657 is an aqueous formulation which is a very low hazard product and has all necessary CEFAS certification for use offshore in the North Sea.

The procedure was a 12 hour boil out, with steam supply from a temporary Zone 2 rated package boiler.


On completion of the boil out, onsite testing indicated that H2S & LEL levels were both zero and the residual inorganic solids were essentially oil free thus minimising waste disposal costs. These results were confirmed by Nexen operations personnel on opening the vessel. The work was completed within the estimated time frame with no incidents, accidents or near misses.


Client personnel were impressed with the efficiency of the process and with the overall cleanliness of the separator on completion of the work. Residual solids were very easily removed compared to previous vessel cleaning procedures and they were classed as low hazard waste for disposal.

The client is now looking to apply this decontamination technology to their other North Sea assets for future turnarounds due to the cost and time savings achieved on Scott and the overall performance of the project.