SPE Projects, Facilities & Construction
Volume 4, Number 3, September 2009, pp. 80-86

SPE-129538-PA

Predicting When and Where Hydrate Plugs Form in Oil-Dominated Flowlines

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DOI  More information 10.2118/129538-PA http://dx.doi.org/10.2118/129538-PA

Citation

  • Boxall, J., Davies, S., Koh, C.A., and Sloan, E.D. 2009. Predicting When and Where Hydrate Plugs Form in Oil-Dominated Flowlines. SPE Proj Fac & Const  4 (3): 80-86. SPE-129538-PA. doi: 10.2118/129538-PA.

Discipline Categories

  • 4.6.1 Hydrates

Keywords

  • flow assurance, hydrate kinetics, hydrate plugs, multiphase flow simulation, CSMHyK-OLGA

Summary

This work provides a means to predict when and where hydrate plugs will form in oil-dominated flowlines. The method was funded by the DeepStar Consortium of Energy Companies and is based on a Colorado School of Mines hydrate kinetic (CSMHyK) model developed over the last six years, which is currently an addition to the transient multiphase program OLGA by SPT Group Inc. The predictions show good agreement to data for hydrate formation in three flow loops with five oils.

Recent CSMHyK-OLGA workshops have been held in Houston (March and April 2007) and Oslo (May 2007), and major companies are beginning to use the program in flow assurance to predict where and when hydrate plugs will form in flowlines.

Introduction

Gas and oil subsea production and transportation are moving to deeper developments where the temperature and pressure conditions are well within the hydrate stability region. The subsequent increased risk of hydrate formation requires new strategies in flow assurance. Traditional methods of thermodynamic avoidance are impractical or uneconomic because of the large amounts of thermodynamic inhibitor (e.g., methanol or monoethylene glycol) required to prevent hydrates from forming under these conditions (Sloan and Koh 2008; Sloan 2000). Transient operations are particularly problematic because of the temporary extreme subcoolings under these conditions. The prediction of hydrate formation rates in these conditions is a major challenge requiring knowledge of the kinetics of hydrate formation, rather than only hydrate thermodynamics. The ability to predict the rate of hydrate formation in subsea flowlines under restart and shutdown conditions is extremely valuable in establishing new operating procedures during transient operations and in flowline design.

© 2009. Society of Petroleum Engineers

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History

  • Original manuscript received: 31 January 2001
  • Meeting paper published: 5 May 2008
  • Revised manuscript received: 26 January 2009
  • Manuscript approved: 3 February 2009
  • Published online: 17 September 2009
  • Version of record: 21 September 2009