Effectiveness of Bypass-Pigging Solutions in Multiphase-Flow Pipelines With Waxy Crude Oil: Evaluation and Innovative Solution

Abstract

and Energy Studies prediction of pig velocity, pig-generated slug volume, slug duration, backpressure increase in the pipeline, and process-plant upset. Control of these parameters is very difficult during bypass-pigging operations because of its transient nature. The fluid behavior through bypass holes, subsequent downstream flow regime, and the nature of turbulence are unknown. Transient modeling and simulation results of bypass pigging with help of the OLGA Dynamic Multiphase Flow Simulator (available from Schlumberger) do not match with actual field results. Wax blockage of bypass holes also leads to erroneous results. In this paper, efforts are made to develop empirical correlations to approximate various parameters on the basis of experimental results in comparison with simulation-model prediction. Later, an innovative bypass geometry/profile is proposed and designed, and experimental results are evaluated. Fluid-Flow Modeling and Dynamic Pig Modeling Understanding the motion of pigs and pig trains in pipelines is important, in general, to avoid surprises. Missed inspection data, damage to pigs, or, in the extreme case, fatality caused by high speeds lead to the need to understand pig acceleration, peak velocity, and how the pig or train might be brought under control. Pig-Motion Analysis. The pig-motion analysis shows the following results (Tiratsoo 1999