When oil is produced, the reservoir pressure decreases and the oil flow rate decreases in proportion to the decreasing pressure difference between the reservoir and the processing facility. At low oil flow rates, a well becomes unstable and this leads to reduced production and processing problems. The formation of slug flow in pipelines is a manifestation of such instability. The front of a slug may be regarded as a propagating, continuously breaking wave, which continuously entrains gas. The Study Group was asked to explore alternative or new ways to treat the gas entrainment problem, to improve understanding of physical processes governing entrainment and to suggest models for the various phenomena. The Study Group obtained mathematical models of slug propagation in horizontal and inclined pipelines, examined possible models of gas entrainment, and outlined an approach to modelling the onset of slug flow. The report summarises that work, and it suggests directions for further investigation.

Problem presented by
Ruben Schulkes, Norsk Hydro

Study Group contributors
Robert Bauer (University of Oxford)
Steven Baxter (University of Nottingham)
Christopher Bell (University of Oxford)
Richard Booth (University of Oxford)
Melvin Brown (Industrial Mathematics KTN)
John Byatt-Smith (University of Edinburgh)
Rebecca Carter (University of Oxford)
Paul Dellar (Imperial College London)
John Fozard (University of Nottingham)
Pragnesh Gajjar (University of Nottingham)
John Garratt (University of Nottingham)
Andriy Hold (University of Eindhoven)
Sarah McBurnie (University of Oxford)
Andrejs Novikovs (University of Oxford)
John Ockendon (University of Oxford)
Dharesh Patel (University of Baroda)
Peter Stewart (University of Nottingham)
Burt Tilley (Franklin W. Olin College of Engineering)
Jean-Marc Vanden-Broeck (University of East Anglia)