Robust Adaptive Control of a Sucker-Rod Pumping System of Oil Wells

Several studies have shown that the satisfactory oil well operations with sucker-rod pumps is attributed to the techniques and methods which are able to control the performance of the well. However, the presence of uncertainties in the sucker-rod dynamical models or parameter variations may jeopardize the desired performance of the control system and the rod pump system productivity. These parameters are normally related to, for example, fluid characteristics in the well, environmental properties at the bottom of the hole, electrical components and mechanical assembly. The purpose of this paper is to use a robust adaptive controller (called IVS-MRAC) to deal with some uncertainties in the system model, unmodelled dynamics, parameter variations, and the presence of perturbations in the automatic level control system of the annular well. The results obtained in simulated environment have shown that the adaptive controller is able to deal satisfactorily with uncertainties and variations, such as for instance, in the pumped fluid composition (water, oil and/or gas), a very common situation in real production fields. The fast transitory with no oscillations (typical characteristic of variable structure systems) is also observed in the plant output and control effort signals. The results are also compared with a conventional PID controller. Key–Words: Adaptive control, Control applications, Oil industry, Process automation, Production control, Robust control, Sucker-Rod pump systems.