Theme #2 MEG Reduction
Current use of thermodynamic inhibitors to prevent hydrate formation may be unsustainable in the cost environment of long tiebacks. This theme focuses on increasing confidence in predicting equilibrium conditions, with the goal of cutting unnecessary margins. Further work is being undertaken to understand the fundamentals of when and how much MEG is actually required to safely operate a subsea flowline.
Hydrate Equilibrium Predictions
Presently, there are significant error margins built into deployment of thermodynamic inhibition systems. In some cases this can lead to a doubling of estimates for the required amount of MEG for full inhibition. Part of this comes from uncertainty surrounding hydrate equilibrium conditions – with secondary safety factors built in on top of these. As…
More InfoPhase Equilibrium Prediction
Currently, there is uncertainty in the quality of both hydrate and solid hydrocarbon equilibrium predictions, further, the interactions of these phenomena are poorly understood. At UWA, we have previously deployed a new simulation package in the form of a new GPA approved tool for solid-vapour-liquid equilibrium predictions – CryoFAST. As part of this current project,…
More InfoNucleation Probability
A key driver for the current over-dosing of MEG into flowlines is the choice to set the steady state MEG flowrate to a level required to inhibit short-lived transient cold spots. In gas condensate systems, these cold spots can be tens of degrees below the freezing point, yet once the system is running normally, it…
More InfoHydrate Management with MEG
Under-inhibited systems are those where the quantity of MEG injected is below the threshold to place the pipeline outside of the hydrate equilibrium region. This operational style has been shown to be viable in avoiding blockages in a number of existing developments, and relies on managing limited hydrate formation by carefully controlling the flowrates of…
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