Digitalized Next Generation Mono Ethylene Glycol Regeneration Systems
Authors: Deshmukh Salim , Larsen Tore , Seereeram Shanta 
Published: November 2020

Offshore natural gas fields are normally developed based on multiphase flow. One of the key challenges for such flow lines may be the risk of gas hydrate formation. This risk can be mitigated by injecting Mono Ethylene Glycol (MEG) into the flow line as a thermodynamic hydrate inhibitor. Due to the large volumes of costly glycol required and the desire to minimise the environmental footprint, the glycol is regenerated on topside or onshore facilities. Presence of salts in the MEG systems make it more challenging to operate them and having full control over the chemistry within the MEG system is key to have successful operation. Today chemistry control within MEG system is largely done by manual sampling and lab analysis as online analysers are either not available or not qualified for the service. Having robust online analysers that can measure water, MEG, pH stabiliser and dissolved salts will minimize these challenges and enable remote operations of the MEG systems.

A Digitalization platform enabling condition monitoring and remote operations system to optimise performance and maintenance efforts on the MEG Regeneration and Reclamation Systems is being developed. The system collects digital input from sensors, analysers, instruments and controllers on the onshore or offshore assets to monitor system behaviour. The uniqueness of the approach to remote operations is our unparalleled process and chemistry expertise in combination with our in-house data science team to produce a system-wide view of the MEG Regeneration and Reclamation system. Current and historical data from MEG Regeneration system are ingested into the data platform, and through custom algorithms, provides full visualisation of the system performance and condition monitoring of critical components within the system. The operating conditions are characterized to reduce downtime and operating costs and maximise production.

Online monitoring of the composition of rich- and lean MEG and formation water breakthrough can improve predictability of the scaling tendency and operation of the MEG plant. This can be achieved by having a qualified set of online analysers that can measure MEG, water and ionic composition online. With this enhanced visibility of the performance and predictive analysis, the need for site visits and troubleshooting efforts can be reduced and repeat failures and unplanned downtime can be prevented.

The digitalization platform and work approach has already been successfully implemented on Sulphate Removal Units/Water Injection Technologies but are new to MEG systems. Qualification programs of critical parameters such as MEG content, chloride and divalent cation ion measurements are being carried out in parallel as part of the digitization efforts.

Selected results from testing of online analysers and the key features from the digitalization platform are presented in this paper.

An online analyser has been tested for simultaneously measuring MEG, water, organic acids and MDEA. The analyser was able to measure these concentrations with a deviation (difference in wt.% concentration) of 0.3 to 0.5%. The impact of relevant process temperature on the MEG and water analysis was minimal.

Similarly, an online analyser has been tested for measuring chloride and divalent ions in presence of MEG. The limit of detection for chloride was about 3 to 9 ppm depending upon the measurement time. The limit of detection for Ca2+and Ba2+ was 3-9ppm and for Sr2+ and Fe2+ was 0.1 to 0.5 mg/l.