Subsea Reliability- Success factors for sustainable deepwater concept development
Authors: Ostebo Runar , Kallestad Ove , Grytdal Idar 
Published: October 2008

Subsea equipment reliability is vital for cost-effective design and operation of deepwater subsea concepts. The OREDA® software and database system allows for monitoring reliability performance and for optimizing subsea system design, as well as infrastructure planning through regularity and reliability focus. Company reliability experiences and examples of industrial cooperation are given. The OREDA Joint Industry Project (JIP) consists today of 10 major oil companies and acts as the Forum for managing and coordinating reliability data collection. The OREDA® subsea software covers subsea equipment such as Xmas trees, control systems, template, manifolds, subsea pumps, and includes critical components such as valves, connectors and sensors. Reliability knowhow is becoming ever more important to utilise in the deeepwater business arena and OREDA offers the "reliability communication language" for the parties involved.

Introduction

There is a high increase in offshore oil & gas production originating from subsea completed wells which requires high attention to subsea equipment and system performance. The demand for safe and cost-efficient operation requires understanding of reliability mechanisms and knowledge to identify and solve issues such as equipment failures, operational problems and human errors. Regularity management is therefore vital for successful business performance and must be integrated into design and operational planning. Deepwater concept developments must include reliability engineering to qualify design and solutions as limited field experience exist.

Low subsea reliability may cause production revenue loss and high cost of downtime and intervention, and would give lack of credibility to subsea completions as opposed to dry wells, or even make the deepwater field development too risky and non-mature. Collection of reliability data is one essential way to learn about weak points in order to improve system design, operation and interventions. Such data can also be applied to predict the availability performance of systems and facilities. As subsea installations may vary both in design and configuration, data needs to be collected and analysed systematically. The OREDA Joint Industry Project (JIP) group has for many years managed and collected equipment reliability data. 10 major international oil & gas companies are currently members. The strengthened focus on deepwater field operations, make it ever more important to coordinate and manage subsea relability data collection, to meet the company and industry demands for qualified data.

This paper will focus on concept developments and its success enablers for robust subsea field developments

The Deepwater Arena

General. Oil companies have been exploring for hydrocarbons in offshore areas at ever increasing water depths around the world. Statoil is one of the operators which is in the forefront of this effort, both through its operations on the Norwegian Continental Shelf and through its increasing international portfolio.

In Norway, there has been a continuous development and maturation of subsea production systems installed in the North Sea since the activity started in 1971 at the Ekofisk field. Starting with relatively simple diver assisted systems controlled via direct hydraulic control systems one are now focusing on complex diverless systems with retrievable modules being remotely operated through multiplexed electro/hydraulic control systems from existing or new infrastructure at varying distances.