Stabilizing gas lift optimization with different amounts of available lift gas

• Here, instability in gas lift operation, has been prevented by a new approach.
• Different case studies has investigated and their effects discussed.
• Results shows that the new method is very effective, inexpensive and applicable.

One of the problems that sometimes occurs in gas lift operations is the instability phenomenon. This phenomenon reduces the oil production and damages down hole and surface facilities. There are many studies on different aspects of this problem but none of them have focused on this phenomenon in a gas allocation optimization problem. Here, as a new approach, instability has been prevented by considering it in the design stage of a gas allocation optimization problem. In this paper, six wells of the Iranian oil field were selected and different amounts of lift gas were allocated among them in a way that the total production was maximized. In each case, the effect of the considering stability was discussed. In addition, about 2000 other wells were investigated to see whether there is any safe situation in which gas allocation optimization can be carried out without any concern about instability. The results indicated that in any case (no matter how much gas is available), it is probable that the optimum point be in an unstable region (of course with different probability). However, by using the method of this study, considering instability as a constraint for the optimizer can lead the optimum point to a stable region with a very small production loss.