Hydrate bedding modeling in oil-dominated systems

摘要

The rapid formation of gas hydrates is one of the major concerns in offshore oil and gas transportation due to the possible plugging of unmanaged hydrate agglomerates. Within the oil and gas industry, hydrate management guidelines have shifted over the last decade from hydrate avoidance to hydrate management. Allowing hydrate formation in pipelines without blockages requires understanding of the hydrate formation and plugging mechanisms under different operational conditions. Furthermore, a predictive tool which can be coupled with the multiphase flow conditions encountered in the field is highly desired in order to ensure successful transportation of hydrate slurries.In the realm of modeling, one such hydrate plugging mechanism that remains unaddressed is the bedding of hydrate particles, which may occur when hydrate particles aggregate within the pipeline. In this work, a bedding model based on force balances has been developed and coupled with a transient multiphase flow simulator. It is proposed that agglomeration controls bedding and bedding is a function of the agglomerate size, which is assumed to follow a log-normal distribution based on an autoclave experimental study. The bedding model has been tested and validated against large-scale flowloop experiments at different water cuts and liquid velocities. Pressure drop comparison between the simulations and experiments shows an improvement after implementing the bedding model for simulations with low liquid velocity. This work may contribute to the understanding of the hydrate plugging mechanisms and be applied to optimize hydrate management guidelines in offshore oil and gas production.