Implementing Deepwater Subsea Reliability Strategy
Authors: Duell C. , Fleming R. 
Published: October 2008

For more than a decade, subsea technology has been perceived as delivering innovative, reliable and cost effective solutions to oil & gas exploitation opportunities. This is reflected in the number of fields, where subsea technology is employed and continues to grow. BP's subsea developments in the United Kingdom Continental Shelf (UKCS) and Gulf of Mexico (GoM) have not however been fault-free. Problems associated with design, metallurgy, quality and operation have impacted primarily on control systems performance.

Although subsea production losses are relatively low in proportion to non-subsea, the cost of failure is significantly higher. These problems are collectively being classified under system reliability. Future confidence in subsea technology could be undermined if deepwater system problems continue to be encountered and poor system reliability continues.

In order to mitigate problems on deepwater developments, BP initiated a Deepwater subsea reliability strategy project in late 1999 with Cranfield University and key subsea equipment manufacturers. The study identified a number of key processes and tools needed to support BP's deepwater reliability vision and define tasks necessary to move the vision forward.

This paper examines the development of BP's deepwater subsea reliability strategy and identifies, implementation progress made to date.

Introduction

As hydrocarbon deposits become depleted in the more accessible regions of the world, exploration for oil and gas is increasingly focused on remote deep-water locations. Some of the largest fields discovered in recent years are in water depths which greatly exceed those for which the industry has operating experience. The exploitation of these developments imposes significant technical challenges. With exponentially increasing intervention costs at such depths, new and innovative technologies will be required for installation and production. In this environment unscheduled equipment failures and planned interventions must be minimised. Prevention of unscheduled intervention will require a step change increase in the reliability of subsea hardwaree.

BP currently operates more than 100 subsea wells in the UK, USA and the Far East, the majority of which are in water depths less than 1500 ft. Our experience of delivering and operating production systems in shallow water has by and large been good, reflecting the use of proven technology in a mature environment. However, in deeper water developments, i.e. greater than 1,000 ft, reliability problems have been more prevalent, and have generally fallen into one of the following categories :Infant mortality failures,Depth & pressure sensitive failures,Environmental corrosion & erosion failures,Salt water ingress failures, andDesign performance failures.

BP's recent discoveries in water depths up 6500 ft will challenge existing deep water development technologies. Potential applications require the use of novel technology in both 10,000 and 15,000 psi technology. This has prompted our initiative to understand and improve the reliability of subsea systems.

BP Reliability Road Map

The first objective in the BP and Cranfield University collaborative project was to develop a road map which defined the path that the project would take to identify the requirements to achieve deepwater reliability. In initiating this reliability strategy, BP's overall goal was to enhance the reputation of subsea technology and ensure that it is perceived as the most cost effective technology for the exploitation of deep-water developments.