Monoethylene glycol reclamation (MEG reclamation) is an industrial process used to remove dissolved salts, corrosion products, hydrocarbons and degradation by-products from monoethylene glycol (MEG), allowing the glycol to be reused in hydrocarbon production systems. MEG is commonly used as a thermodynamic hydrate inhibitor in subsea pipeline systems, where it is injected into production fluids to prevent the formation of hydrates that could obstruct flowlines. MEG reclamation is principally employed in offshore natural gas developments, long-distance subsea tie-backs, floating production storage and offloading facilities (FPSOs), and onshore gas-processing plants. The process is often integrated with MEG regeneration systems that remove water from the recovered glycol stream.
Background The use of MEG as a hydrate inhibitor became increasingly common with the development of deep-water oil and gas fields and long-distance subsea production systems. Unlike methanol, MEG can be recovered, purified and re-used, reducing chemical consumption and operating costs. As production fluids travel through pipelines, the recovered MEG becomes contaminated with dissolved salts, corrosion products, hydrocarbons, production chemicals and degradation compounds. Without reclamation, these contaminants can accumulate and adversely affect process equipment and flow assurance performance.
Regeneration and reclamation Although the terms are sometimes used together, regeneration and reclamation describe different stages of MEG recovery.
Regeneration MEG regeneration is the removal of water from recovered glycol streams. The process typically employs distillation to increase the MEG concentration to the level required for reinjection into production systems.
Reclamation MEG reclamation is the removal of dissolved and suspended contaminants, including monovalent and divalent salts, corrosion products and degradation compounds. Reclamation is intended to maintain glycol quality and limit the accumulation of contaminants within the MEG circulation loop. Many facilities incorporate both regeneration and reclamation processes within a single recovery system.
Process configurations MEG reclamation systems are generally configured using either a full-stream or a slip-stream reclamation process.
Full-stream reclamation In a full-stream system, the entire rich-MEG return stream is processed through the reclamation unit to remove salts and other non-volatile contaminants. Full-stream systems are frequently integrated with regeneration facilities to provide simultaneous water removal and salt removal.
Slip-stream reclamation In a slip-stream configuration, only a portion of the circulating MEG is treated for salt removal while the remainder undergoes conventional regeneration. The selection of reclamation philosophy depends primarily on anticipated formation-water production rates, salt loading, chemical management requirements and overall system economics.
Technology MEG reclamation systems generally employ combinations of:
Vacuum distillation Modern MEG reclamation systems commonly employ vacuum distillation to recover monoethylene glycol while avoiding thermal degradation. Operating under reduced pressure lowers the boiling temperature of the MEG-water mixture, allowing salts and other non-volatile contaminants to remain in the reclaimer while purified MEG is recovered and recycled.
Salt precipitation Filtration - Filtration is commonly employed within monoethylene glycol (MEG) reclamation systems to remove suspended solids, precipitated salts, corrosion products, pipeline debris, and oxidation by-products that accumulate in the MEG circulation loop. Solids Separation Technologies This includes decanter centrifuges, gas-tight centrifuges, and basket centrifuges
Solids handling and disposal systems The specific process arrangement varies according to contaminant loading, required glycol purity and the characteristics of the produced water.
Control of Oxygen Research into MEG reclamation systems has shown that control of dissolved oxygen is a critical aspect of process design. Oxygen ingress, particularly in high-temperature, salt-containing MEG environments, can promote localized corrosion of process equipment, including duplex stainless steels. Studies have found that corrosion is most likely to occur where salts are deposited, while minimizing oxygen ingress through system integrity measures, gas blanketing, and oxygen control practices can significantly reduce corrosion risk.
Commercial suppliers A number of companies supply MEG regeneration and reclamation technologies for offshore and onshore hydrocarbon production facilities.
SLB markets the PureMEG regeneration and reclamation system. NOV Inc. supplies slip-stream and full-stream MEG recovery systems. Axens markets the AdvaMEG process for MEG regeneration and reclamation. Veolia supplies glycol regeneration systems for oil and gas applications.
Notable installations MEG processing and reclamation technologies have been implemented in a number of major onshore and offshore gas developments worldwide. Below is a list of units by Continent :
EUROPE - Norway - Ormen Lange, Åsgard B, Gjøa Field - UK - Britannia Satellites - Laggan Tormore (Shetland Islands)
North and South America - United States Gulf of Mexico - Shell Mensa WD-143 Offshore Project, Independence Hub - Brazil - Mexilhão Platform (Petrobras - Santos Basin), FPSO Cidade de Santos (Santos Basin)
AFRICA and MIDDLE EAST - Mozambique - Coral Sul FLNG / Coral North FLNG (Mozambique) - Saudi Arabia - Wasit Onshore Gas Plant - Egypt - West Nile Delta
ASIA - Azerbaijan - Shah Deniz - India - KG-D6 - China - Liwan Gas Field
OCEANIA - Australia - Prelude FLNG has a large MEG Reclamation Unit as referenced here. Pluto-LNG FPSO Ichthys Venturer
- Otway Gas Plant (OGP) - Beach Energy New Zealand - Kupe The use of MEG reclamation technology is particularly common in deep-water gas developments requiring long subsea tie-backs.
See also Ethylene glycol Gas hydrate Flow assurance Subsea pipeline Natural gas processing
References
Xia, Zhi; Jinlin, Hou; Li, Zhijun; Zhou, Xiaohong (2017). "General Design of Lean MEG Storing in the Jacket Legs on Liwan Gas Field of South China Sea". Offshore Technology Conference. Houston, Texas, USA: Offshore Technology Conference. OTC-27526-MS. Al-Khaldi, M. H.; Al-Juhani, A. M.; Al-Mutairi, S. H.; Gurmen, M. N. (2011). "New Insights into the Removal of Calcium Sulfate Scale". SPE European Formation Damage Conference. Noordwijk, The Netherlands: Society of Petroleum Engineers. SPE-144158-MS. Latta, T. M.; Seiersten, M. E.; Bufton, S. A. (2013). "Flow Assurance Impacts on Lean/Rich MEG Circuit Chemistry and MEG Regenerator/Reclaimer Design". Offshore Technology Conference. Houston, Texas, USA: Offshore Technology Conference. OTC-24177-MS.
Further reading Odeigah, E.; Pojtanabuntoeng, T. Regeneration and Reclamation of Mono-Ethylene Glycol (MEG) Used as a Hydrate Inhibitor: A Review. American Journal of Chemical Engineering, 2022. Crawley-Boevey, S.; Jariwala, A. Offshore MEG Regeneration and Reclamation Units: Lessons Learned from their Design and Operation.