On the Subsea Production System Availability with Resident Drones. A Reliability, Availability, Maintenability RAM Analysis

The challenge in the Oil&Gas industry to remain competitive in a low oil price whilst dealing with minimization of operational risk and uptime asset maximization is leading offshore Companies to evolve thought proactive and predictive maintenance approaches. In the event of unplanned intervention due to anomalies or warning messages at the dispatching center, the decision on the size of the support vessel and its utilization for straordinary maintenance could be time consuming with potential high cost impact, also due to loss of production. Even the new generation of remote condition and monitoring systems, which allow to improve the capability of operators for early warnings and surveillance, provide a reliable solution for emergencies. In this context, resident subsea drones enable on-demand inspection whilst eliminating the need for support vessel and allow operator to manage the risk in continued operations also for dangerous areas restricted to human access. A case study relevant to a new subsea field development have been conducted. Distinctive Reliability, Availability and Maintainability (RAM) analyses have been performed with the aim to get insight on the subsea production system availability considering a resident drone and to demonstrate how the so called "stategic maintainability" can be applied successfully in the decision-making process while reducing the OPEX. The former related to conventional IMR (Inspection, Maintenance & Repair) based on Condition Based and RBI, Risk Based Inspection approach, the latter related to strategic maintenability with resident drones. The application of such analysis required a multi-disciplinary approach together with the possibility of processing historical data in operating conditions. Historical data sources (e.g. OREDA dataset) were collected to obtain failure rates and active repair times typical of subsea equipment. Direct experience gained in over forty years of inspection and maintenance activities together with recent developments on subsea resident robotics allow the understanding of real internvention timing. Results show that resident subsea drones applied for early inspection and light intervention are confirmed timely and costless solution respect to conventional IMR services. They represent the first aid for environmental surveillance and subsea inspection in case of emergency and provide a relevant saving of subsea production un-availability. The economic value emerged from the presented case study represents a step change for OPEX optimization and motivates Best-in-Class Operators to get an insight case-by-case for both green and aging fields.