Improving Safety Through Logic: Programmable Logic Controller for Conventional Casing Running Equipment

Abstract

Abstract Running casing with conventional equipment is a labor intensive process requiring multiple personnel on the rig floor. Due to the dynamic environment of running casing with this equipment, there is elevated potential for accidents. Two specific operational hazards associated with hydraulic power tong operations (the "mule kick" and "rattlesnake") have been addressed, and the authors are developing solutions to mitigate future related incidents. A new system, utilizing a programmable logic controller (PLC) and position sensors, as well as hydromechanical and electromechanical devices, has been devised to reduce the chance for injury and enhance safety for casing power tong operators. Risk mitigation through engineered safety controls is a primary objective for service companies, and the operators and contractors they work with. Hydromechanical, electromechanical, and electronic control (PLC) devices for land-based, conventional casing equipment are under development and revision. These devices are being customized for incorporation into power tongs and hydraulic power units. In conventional operation of power tongs, the power unit modulates the amount of hydraulic power provided to the tong based on required flow rate and pressure. The PLC provides the ability for electronic communication between the power tong and power unit, virtually eliminating lag in response time. The logic control can also determine, based on the magnitude of tension in the backup line, if the tongs are actively in make-up or break-out mode. These devices under development will prevent the violent backlash and stored energy associated with the "mule kick" and "rattlesnake". In addition, due to the flexibility of the system, Human Machine Interface (HMI) screens can be provided to adapt the system to changing conditions. The application of the logic controller and mechanical devices on land-based, conventional casing running equipment is a significant step in reducing operator and equipment error, and increasing the casing crew's safety threshold. This paper will discuss the evolution of this system, from conception to application.