Certified battery shut down system

Today, valves on subsea wells are controlled by actuators with hydraulics, supplied and controlled from a platform through umbilicals. In case of a shutdown, the hydraulic pressure drops, and the valves are forced to a closed position by mechanical springs installed on the valves. Subsea systems are now being placed deeper and further away from topside-based processing plants. This requires longer umbilicals, larger topsides, larger mechanical springs, and increased hydraulic volumes stored subsea. This means increased investment costs, making some field developments not commercially attractive (marginal fields). Adding new wells to existing infrastructure (tie-ins) also becomes more complex and costly with hydraulics. Moreover, hydraulics will not support digitized monitoring and individual control of valves, which, if implemented, would have improved production-volumes, uptime and safety. The industry is therefore increasingly focused on finding electrified solutions for subsea development. Aker Solutions with partners are developing an electrical system with batteries replacing mechanical springs, and with a new control system that will improve monitoring, reliability, response time, flexibility, and cost. This electrical solution will make subsea oil and gas production safer, more energy efficient, more cost efficient, give higher uptime, and produce larger volumes than a comparable hydraulic solution. As per Dec 1 2019 the concept phase is closing as the final system requirements are being determined by the partners.

The research is concluded and it has pointed the technology to be qualified on its best possible manner. It was concluded and proved to be very difficult to control an Actuator Control Module with a sensorless control solution and not to be the best alternative to meet safety integrity level 2 requirements. As a way forward, the Actuator Control Module technology qualification will continue using a sensor motor control implemented in a Programmable Logical Device (PLD). The defined solution will enable the PLD motor control to be rated according to Safety integrity Level (SIL) 2 requirements and certified according to IEC61508.

The more stringent requirements for operating SPS systems at larger depths and in more environmentally vulnerable areas are pushing the industry towards developing all-electric solutions, replacing hydraulics with electrical motors to operate subsea valves. The solutions that have emerged so far focus on controlling the valves using electric motors, while keeping the spring to do the FSC shutdown. For deep water this is a problem as the spring will become prohibitively big. The underlying idea for this research project is therefore to demonstrate a solution that enables the use of batteries placed subsea to close valves to a safe state. Enabling this technology in a cost efficient way will make the all-electric system safer, more reliable, more environmentally friendly, more cost competitive, and give higher performance. The innovative new approach is to have the electrical motor control function moved into a simpler logic device which is believed to be more robust. This research will determine the feasibility of the proposed solution by studying and understanding the interaction and hierarchy involved in controlling normal process operations (PCS), controlling process shutdown (PSD) and emergency shutdown (ESD) operations. The research will be done at Aker Solutions and at NTNU where a post-doc program is in the planning. For Aker Solutions this research project and the funding from Petromaks2 is crucial; without the funding we will lose speed and miss the opportunity to put the involved parties in the forefront of the ongoing offshore electrification initiative • Norwegian research at the international forefront of subsea electrification and digitalization • Safe, efficient and competitive production from Norwegian waters • Norwegian suppliers get an edge and thereby securing Norwegian engineering and manufacturing jobs. Being first Aker Solutions will bring global contracts to Norway from a market estimated to 7 BNOK over the next 10 years.