Abstract
ANALYSIS OF SUBSEA FLOWLINE SIZING FOR SLUG MITIGATION
Ugochukwu H. Ilonze and Tobinson A. Briggs*
ABSTRACT
Slug flow has proven to be a menace in the production of Oil and Gas; from cyclic loading of pipelines, which could cause fatigue, to water overflow in the separator. This work established the presence of slugging in a typical Field A and created a prototype that could mitigate it. In work, the diameter of the existing subsea flowline was varied from 0.3715m to 0.05m and observed using OLGA 2016 software after which the optimal configuration was obtained. The obtained prototype created a constriction towards the riser-base, making the flowline to have a varied internal diameter. Liquid hold up, Pressure, Oil volume factor and Water volume factor were simulated and plotted against time, and these plots showed the slug was mitigated with the application of the prototype. The Sensitivity analysis on the mass flow rate with simulation ran from 20kg/s to 40kg/s after which it was confirmed that the mass flow rate does not affect the prototype. A parametric study was also run on the pipeline span to observe its effects on slug mitigation. The pipeline span was increased from 100m to 400m after which the 300m liquid hold up against simulated time plot showed slug flow for only 250 seconds and then stabilised, which made its selection possible. This prototype if applied to a subsea flowline close to the riser base, would mitigate slug flow and its accompanying problems.
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