Modelagem e simulação de uma unidade de bombeio mecânico convencional utilizando o ambiente Simscape Multibody™

Abstract

The Sucker-Rod Pumping (SRP) system is the most used artificial lift method in oil wells in Brazil and in the world. The widespread use of this method can be justified by its relatively simple, reliable and durable structure, convenient maintenance, etc. Due to the popularity of the SRP systems in the oil industry, over the years, many studies have been developed to contribute to the evolution of the method. Recent computational advances have allowed the development of SRP simulators, as well as software for modelling and simulation the SRP system. Thus, there is an opportunity to develop a more accurate model, capable of accurately reflecting the operation of the Sucker-Rod Pumping Units. In this context, this work proposes to model a conventional SRP Unit using the tools of the Simscape Multibody™ (a MATLAB’s library of the Simscape™ environment for modelling and simulation of physical systems), and to carry out specific studies with the developed model that are not commonly seen in the current literature. Among these studies, using the developed model, a sensitivity analysis was first performed with the objective of evaluating how the inclusion of dissipative friction forces in the components of the SRP unit can impact the resulting gearbox torque curve. Furthermore, simulations were carried out with the objective of demonstrating how the application of a variable speed drive profile throughout the pumping cycle (intra-stroke speed profile) can contribute to the improvement of the equipment's operation. As a result of this study, it was possible to demonstrate the feasibility of manipulating and redistributing the intrastroke speed profile to achieve objectives such as: counterbalancing the SRP unit and keeping the gearbox maximum torque of the equipment within the recommended limits, as well as reducing the region where the net torque values were negative. Additionally, it was also possible to increase the pumping speed in the section where the net torque of the system was negative, and the increase of the pumping speed did not cause an increase in the maximum peak torque experienced by the equipment. This result is relevant because it shows that is possible to improve the operation of the pumping units, considering that the increase in speed can provide a greater oil flow rate due to a higher average pumping speed. In order to validate the developed model, simulations were performed and the obtained results were compared to other traditional calculation methodologies existing in the literature. Moreover, it was analysed whether the behaviour of the modelled system was consistent if compared to what can be seen in practice when certain procedures are performed in real SRP units.