Predictive Analytical Model for Hydrate Growth Initiation Point in Multiphase Pipeline System

Abstract

Gas hydrates account for a huge flow assurance encounter in the passage of natural gas through pipelines. Its undesirability stems from the fact that these solids reduce pipe diameter open to gas flow, and challenge pipeline integrity, therefore leading to bursting pipes and increasing costs. Hydrates undergo four phases of development: entrainment, growth, agglomeration and plugging – and do not usually constitute a flow assurance challenge until agglomeration. These challenges are even more pronounced in the presence of condensate in the pipeline. This study was therefore designed by developing a predictive model of the hydrate growth initiation point along the pipeline where hydrates start to form in the presence of gas, condensate, and water. The developed predictive analytical model at which quasi liquid layer starts to form on the hydrate seed relates the quasi-liquid layer temperature to the gas hydrate mass, pipeline length, induction time, hydrate percentage in the fluid composition, hydrate density, change in enthalpy and the flowing hydrate velocity in the pipe system. The developed predictive model will assist in identifying when heating of pipelines can be done to control hydrate formation by keeping the temperature above the quasi-liquid layer temperature. This predictive model was in concordance with field observation.