Selection of subsea distribution systems

Abstract

Equipment repair and intervention in subsea oil and gas fields are expensive, mainly due to vessel mobilization time, retrieval, repair, and replacement costs. The loss of revenue due to downtime could also be significant and the producer could face penalties in not meeting contractual commitments. These costs are part of the life cycle cost, which must be considered at the design stage. Estimating the reliability and availability of subsea systems at an early stage of design is important in assuring the quality of the system architecture, which leads to a more reliable choice of configuration and equipment. Availability analyses should be undertaken very early in the development process, while the operational concept is still under review, and the choice of components is still to be finalized. Postponing this assessment could prove to be too costly to improve the availability and dependability.This paper presents a reliability assessment using a systems engineering framework by combining the system's requirements and reliability requirements. A Design Structure Matrix (DSM) is employed to map the system and visualize the inter-relationships (dependencies) between components/subsystems. The DSM is then augmented with reliability data, including intervention times, to determine the overall system availability. It is also explained how to use the system's DSM to aid integration and interface management decisions. A case study is presented to demonstrate this procedure.