Working together for a safer world

How to control reliability levels of subsea production

systems during operations?

Inge Alme

February 2015

Reliability levels of subsea systems in operation

Reliability of subsea systems

• High requirements to availability of the

systems to be able to achieve the necessary

production rate

• The reliability of the systems is typically

analysed during the design phase, given certain assumptions and operational

parameters

• High reliability is also a condition for high safety level and low environmental risks

• Design is optimized to achieve the necessary reliability levels, i.e. high degree of

redundancy of critical components and important barriers.

Reliability levels of subsea systems in operation

Decision making in the operations

• What happens if a component failure is detected during operations?

• Is the information in the technical specification sufficient for important insights?

• How critical is the failure?

• How will the failure affect the current reliability level?

• Do we need to stop the production?

• Do we need to inspect and/or repair the equipment/components that have failed?

• What happens if a periodical test interval for a critical safety function is extended?

• How will the extension affect the availability of the function?

What is the basis for these critical decisions that have to be made by the operators?

Reliability levels of subsea systems in operation

Experiences from other industries

• Nuclear industry

• Pressure from US regulators in the 90’s pushed the

development of risk monitors to be used to get updated

picture of risk as input to maintenance planning

• The use of risk informed approaches allows both regulator

and the industry to focus on important safety issues

• INPO Performance Indicator Index from 1995 to 2004 for US

plants shows that plants with risk informed decision making activities have increased profitability with no degradation in

safety compared to other plants

• Deepwater drilling industry

• Significant focus on risks related to BOPs after Macondo

• A BOP risk model developed and implemented on some rigs

Reliability levels of subsea systems in operation

BOP Risk Model

Reliability levels of subsea systems in operation

BOP Risk Model Interface

Reliability levels of subsea systems in operation

How could this look like for other subsea systems?

Input from design (FMECA, SIL,

documentation, RAM studies etc.)

Requirements from regulations,

standards, rules, etc.

Input from

operations, incl. barrier strategy,

operational

philosophy, etc.

Automatic input from control

system

Manual input from operators

Live reliability model for subsea

systems

Reliability levels of subsea systems in operation

Calculation of ‘real time’ reliability level (Safety Integrity Level) of the

critical functions

Reliability levels of subsea systems in operation

Use of operational data

• The model can use generic data

• The generic data can be updated when enough specific data is available, e.g. enough events in the event history

Data update

Reliability levels of subsea systems in operation

Take into account the test interval of components

Reliability levels of subsea systems in operation

The importance of the different components

• The operator will continuously be able to check which components that are the most

important (or vulnerable)

Reliability levels of subsea systems in operation

Implementation of a live risk model

Operational staff use the risk model, updating the

ONLINE event history daily

Staff in the system owner’s offices, Oil company offices,

and regulator offices use risk model for Planning,

viewing, and other applications

Backups are made continuously the same way as for

all other files on the server

Technical support for software, risk model update, etc.

Reliability levels of subsea systems in operation

The benefits of risk modelling of subsea systems

• Real time monitoring risk qualitatively and quantitatively

• Input to better design solutions

• Calculating Allowed Outage Time and cumulative risk

• Decision support in critical situations

• Planning of maintenance outages to reduce risks

• Long term risk profiling

• Analysis of cumulative risk

• Evaluation of unplanned events

• Training

• Feedback – lessons learnt

Lloyd’s Register and variants of it are trading names of Lloyd’s Register Group Limited, its subsidiaries and affiliates.

Copyright © Lloyd’s Register [Entity]. 2014. A member of the Lloyd’s Register group.

Inge Alme Global Account Director Lloyd’s Register Group T +47 928 86086 E inge.alme@lr.org Lloyd’s Register Group 71 Fenchurch Street, London EC3M 4BS

Working together for a safer world