Chemical consumption and wash water usage has risen in the past few years due to oil production having increasing water cut and emulsions. Saudi Aramco has installed and tested a new chemical injection spool that enhances the mixture of the injected chemicals and the incoming multiphase flow. The test consisted of two chemical injection spools: 24 in. and 30 in. units.

The injection mixing spool has no moving parts and is installed upstream of the separator at the gas-oil separation plant (GOSP). The mixer incorporates specialized injection ports that channel the chemicals into grooves that ring the pipe and provide 360 degree injection. In addition, the internal geometry of the mixer generates turbulent eddies that enhance mixing. This static mixing spool has three injection ports: demulsifier, corrosion inhibitor, and scale inhibitor.

The first system (24 in.) was installed and commissioned during the plant's maintenance in April 2013. The trial test of the chemical injection mixing spool spanned the summer months, which typically see a lower chemical consumption, as well as the winter months. Since being set on stream, the system has achieved a 48% reduction of demulsifier injection, which is a costly chemical. In addition, the wash water consumption was reduced by 31%, which supports the reduction of overall ground water consumption. These improvements were achieved while maintaining process integrity and desalting train efficiency.

The second system (30 in.) was installed and commissioned similarly in May 2014. This unit achieved a 17% reduction in demulsifier dosage. Also, the reduction in wash water consumption was estimated at 12%.

This paper describes the background to conventional chemical injection and mixing, specialized mixing spool design and working principles, implementation, and impact of the installation of the chemical injection mixing spool.

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