A set of small-scale air/water experiments has been carried out in a flowline/riser system to demonstrate how local gas accumulation in regions upstream from a riser or a well may give unstable flow, with cycling liquid production at the riser outlet. This unstable flow phenomenon differs from the well-known severe-slugging instability phenomenon in that the instability is driven by gas expansion in the riser, and not by expansion in the upstream pipeline.

A Lagrangian slug tracking model was extended with the option of solving problems with entrained gas in slugs, and used to simulate the experiments. A simplified pressure/momentum scheme is applied. Sensitivity analyses were carried out for selected parameters. Good correspondence between experiments and simulations was found with respect to the period of the instability cycle for this gravity-dominated system. The experimental stability limits are also well reproduced.

You can access this article if you purchase or spend a download.