Modified distributed delay model for void wave dynamics in gas-lifted wells

Oil well instabilities cause production losses. One of these instabilities, referred to as the “density wave” or “void wave”, is an oscillatory phenomenon which occurs in gas-lift oil wells. A modified distributed delay model is presented for this dynamic behavior 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 simulation studies are subsequently carried out using OLGA as a realistic multi-phase flow simulator. It is shown that the resulting model and its corresponding stability margin are more consistent with observations obtained from well operation facts, compared to the results reported from the previous works.