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Investigation of Self-Lifting Approach for Slug Attenuation in Inclined Pipeline-Riser System

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Investigation of Self-Lifting Approach for Slug Attenuation in Inclined Pipeline-Riser System

ABSTRACT

This study evaluates the use of self-gas lifting in the mitigation of severe slugs. OLGA was used to develop the pipeline model and Multiflash for fluid characterization. Two OLGA cases were created, a base case pipeline model which was inclined at 5° to the riser base and also a 5° inclined pipeline to the riser base but with an auxiliary bypass line to lift the flow at a certain point above the riser base. A phase splitter process equipment which acts as a take-off point along the pipeline and function as an internal node and a separator network was place along the pipeline and riser. The phase splitter allows only gas to pass through the ‘bypass line’ and liquid through the ‘Subsea Tieback’. The bypass pipe of internal diameter 3-inch was connected to the take-off point at 535.455ft from the riser base along the pipeline and to an internal node which serves as the injection point into the riser at 20ft from the riser base. Results shows that an auxiliary self-lift bypass line was very effective in attenuating severe slugging in a pipeline-riser system and a stable liquid production of 2728.93bbl/day at the topsides was obtained when an auxiliary bypass line was used as a gas re-injection line into the riser column whereas for the case of 5° inclined pipeline without a bypass line, the total liquid flow was oscillating between 46776.3bbl/day and -3646.44bbl/day. Slug flow was completely eliminated for the model with bypass line as evidenced by the more stable pressure. The highest riser pressure was 291.327psia over the duration of the 2hrs, which was lower than the slugging model without a bypass line (299.595psia). The auxiliary self-lift bypass line was very effective in mitigating slugging in the pipeline -system.

Keywords: Self-Lifting Approach; Slug Attenuation; Inclined Pipeline-Riser System

Authored by

1Bright Bariakpoa Kinate, 2Emeline Adaoma Temple and 3Ayauwu Ayauwu Loveday

FULL PDF   |  DOI: 10.5281/zenodo.7844395

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