Design of gain scheduling control strategy for artificial gas lift in oil production through Modified Relay Feedback Test

Abstract

One of the major problems encountered in artificial gas lifting is the stability of production from wells were gas lift may show a highly oscillatory behavior, and hence production varies greatly with time. This paper presents methodology of design of a gain scheduling strategy based on a new physical model of artificial gas lift in oil wells. The model was preliminarily validated by comparing the states dynamics with other models from the literature which have been replicated. The Modified Relay-Feedback-Test (MRFT) method was used to calculate the PI controller parameters, and the model reached steady state for different operating points. Gain scheduling was then performed following the MRFT results to provide a simple PI controller tuning parameters for the automatic control and optimization of the production from the oil well, and to compensate for the casing-heading instability in the system.