Flow Assurance Impacts on Lean/Rich MEG Circuit Chemistry and MEG Regenerator/Reclaimer Design

Abstract

Abstract The chemistry of the Lean and Rich monoethylene glycol (MEG) closed loop circuits is dictated by decisions made by the flow assurance design team. During the life of the gas reservoir both short term events (e.g., completion fluids) and long term events (e.g., corrosion control, scale inhibitors, hydrate inhibition, formation water flow) need to be considered, as well as their effects on the Lean/Rich MEG circuits which need to be confirmed through appropriate testing and simulation. The result of this flow assurance work and testing/simulation is to ensure that proper design criteria are established to minimize detrimental precipitation tendencies in the Lean/Rich MEG circuits and to provide criteria for the MEG regenerator/reclaimer design. This paper is applicable to subsea gas wells using MEG for hydrate inhibition. The paper outlines a holistic approach, to ensure that the MEG regenerator/reclaimer is properly designed, by emphasizing that three key groups are involved, which are, the flow assurance group (wellhead chemistry), testing/simulation facility (corrosion program/precipitation study), and the hydrocarbons process group (processing facility/MEG regenerator and reclaimer design). Each well has its own unique chemistry and injection chemicals. Previous work involving MEG injection for hydrate inhibition indicated the need to inform and involve the client regarding the necessity to consider all aspects of the flow assurance program and to ensure appropriate testing/simulation work is completed. This will confirm if any detrimental precipitation occurs in either Lean or Rich MEG circuits (especially if a MEG reclaimer bypass option is used to produce " salty" Lean MEG). Effective communication and collaboration are required between the flow assurance and hydrocarbons process design teams, as well as the testing/simulation facility, to create a proper design package for the MEG regenerator and reclaimer units, that takes into consideration the chemistry of the Lean and Rich MEG circuits. Key items/actions that need to be considered during conceptual design and front end engineering are outlined. If precipitation tendencies are well understood then the MEG reclaimer design can be optimized to reduce footprint and weight which are key objectives for offshore platforms.