Identifying Optimal Pigging Frequency for Oil Pipelines Subject to Non-Uniform Wax Deposition Distribution Available to Purchase

Wax deposition in oil pipelines causes reduced throughput and other associated problems. Periodical pigging program can effectively minimize the cost of wax deposition. This paper shows a typical pigging case study for a field pipeline subject to non-uniform wax deposition distribution by using a developed wax deposition model. The model prediction results prove that the wax is distributed in a short, localized accumulation along the first half pipeline. The resultant pressure drop along the pipeline was examined to reveal the effects of non-uniform wax deposition distribution on the pipeline production. In extreme case, the pressure drop of severe localized section increases by 50%, while this value between pump stations is merely 3%. A maximum wax thickness of 2–4 mm is used as a criterion to determine an optimal pigging frequency. The case study pipeline is recommended to be pigged at a frequency of 10 to 15 days, using by-pass pigs.