Downhole Electrical System Development Based on Reliability: A Step Forward for High-Performance Subsea Well Completions

Abstract The success of completion systems in subsea wells relies on reliability and functionality. Traditional systems face challenges, leading to electrically driven solutions. These include intelligent completion, downhole safety valve, electro-hydraulic downhole wet disconnect system, metallic expandable openhole feedthrough packers, gas lift valves, chemical injection valves, and subsea interface. Electric solutions aim to ensure high availability throughout the well lifecycle. The proposed methodology estimates and monitors reliability metrics during all development stages. It consists of a multilevel system reliability model, Bayesian estimation, uncertainty analysis, optimal testing protocols, and design change recommendations. This standardized approach enhances the R&D process of completion systems with high reliability requirements. The proposed methodology is a systematic procedure that effectively evaluates reliability metrics. It aggregates various types of data, enabling the monitoring of reliability and uncertainty evolution during each stage of R&D. It also calculates accelerated test durations based on the probabilistic physics of failure and stress-life relationships for systems, subsystems, and components. This approach addresses challenges in the development process, including heterogeneous information sources and limited long-term data for new technologies. Compared to current reliability methodologies, which rely on reliability demonstration tests, the proposed methodology enables control and monitoring of the development process. By setting reliability and uncertainty targets, the evolution of these values can be tracked across Technology Readiness Levels (TRLs). This is achieved through a Bayesian approach that updates the reliability function as new evidence emerges. The proposed methodology was on various data types from different completion systems, yielding satisfactory results. This represents a milestone in the development of completion systems and serves as a valuable reference for enhancing solutions and processes in well engineering. Collaboration with operators, service companies and academia has played a crucial role in the implementation of this new methodology to understand the different approaches being used in the industry and their weaknesses.