Sucker-Rod Pumping System of Oil Wells: Modelling, Identi_cation and Process Control

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, for example, of uncertainties in the sucker-rod dynamical models or unmodelled dynamics, related to fluid characteristics in the well or associated with the mechanical assembly, may jeopardize the desired performance of the control system and the rod pump system productivity. The purpose of this paper is related to two main objectives. First, a mathematical dynamic model of a real sucker-rod pump is developed based on identification techniques by using input-output measured data. Second, an robust adaptive controller is used 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 have shown that the developed model is representative and 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. Experimental tests were conducted in a real plant to check the validate and robustness of the used controller algorithm. The results are also compared with a conventional PID controller.