Otimização do sistema de elevação artificial por bombeio mecânico através do controle de peak torque e submergência

Abstract

Automated well control applied to artificial lift methods has recently gained attention in the oil industry. This has been applied to artificial lift methods, especially in sucker-rodpump (SRP), which is the most used method in onshore oil wells in Brazil and in the world. The profuse application of SRP as a lift method is due to its relatively simple, reliable and robust structure, under suitable conditions (proper maintenance) it can be used until the end of a well's productive life. The developments applied to the SRP contributed to advances in computational tools and the development of automatic control strategies. The recent computational tools provided the development of simulators and automation allowed the development and application of new strategies and control techniques. Then, the main objective of this work was to develop, apply and validate an appropriate control strategy applied to a conventional pumping unit, using peak torque and submergence as control parameters. The control action aims to increase the operation flow rate to generate significant revenue even under internal and external disturbances. At first, mathematical and computational modeling to determine the torque curve on the reducer using the trigonometric model, and concomitantly, the submergence was calculated. In a second moment, an override control was developed with two Proportional-Integral-Derivative (PID) controllers, theses were used due to its versatile structure, adapting to requirements and work limitations. The control was implemented using the Visual Basic for Applications (VBA) programming language associated with its integrated development environment (IDE) (which is present in Microsoft Excel). The control strategy has been validated through simulations performed using virtual wells. These simulations demonstrated that the developed strategy achieved satisfactory results. As a contribution of the work, it was possible to observe the maximum performance of the conventional pumping unit, within its operational limits with the insertion of the peak torque and submergence controls. Additionally, we noticed an automatic change in the pumping speed during the production process, avoiding stops in the system. Operating at the torque limit made the process speed increase, providing a higher production flow. The submergence control, in turn, acted to prevent the well from drying out and preventing the existence of possible operational problems, such as gas interference and pump-off.