Abstract
The traditional method of managing hydrates in production systems has been complete avoidance. This methodology comes at a high cost of insulation to maintain fluid temperature beyond the hydrate formation temperature and/or chemicals to prevent hydrates from forming. This paper will present methods to assess hydrate formation/plugging tendencies and manage the system in a manner that allows for reduction in insulation requirements and/or chemical usage.
ExxonMobil's Upstream Research Company (EMURC) has developed a unique hydrate slurry model based on experience gained in the laboratory and field applications. Cold restarts are different than allowing fluids to remain cold indefinitely (i.e. cold flow) in that the hydrates form for a period of time before the system eventually comes out of the hydrate formation region in "steady-state/normal" production. This presentation will show how the model is used to assess hydrate blockage potentials by integration with a transient multiphase flow simulator. This enables the model to predict amounts of hydrates that form and couple the formation with flow dynamics such as shear conditions, phase fractions, and dispersion characteristics which influence the probability of a hydrate blockage forming.
The model has been applied successfully to several applications by assessing various cold restart strategies in which significant cost savings have been realized through the reduction of insulation requirement and/or chemical usage – in some instances it has allowed for the extension of field life.
