Predicting void wave instability in gas-lifted wells

Oil well instabilities cause production losses. One of these instabilities, referred to as the "void-wave" is an oscillatory phenomenon occurring in gas-lift oil wells. A modified distributed delay model for this dynamic is presented in this paper. Then, the proposed model is used for stability analysis of a hypothetic gas-lift oil well undergoing this type of instability. Stability analysis is performed via small gain theorem and simulations are done using a realistic multiphase flow simulator. Resulting model and its corresponding stability margin are more consistent with well operation facts, compared to the results from the previous works.