At the end of their production lifetime, oil wells tend to produce in an unstable, cyclic manner. One of these flow instabilities, the density wave instability, appears in gas-lifted wells. Numerical simulations with the software program OLGA show for which conditions the density wave instability appears. Experiments have been performed on a two-phase test facility to verify the numerical results.
Traditionally unstable flow is suppressed by choking at the wellhead, resulting in increased backpressure, hence production deferment. OLGA simulations show that the Shell Smart Choke algorithm can be used to mitigate the density wave instability with larger average choke opening.