Hybrid Riser Tower Monitoring An Operations Perspective
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Hybrid Riser Tower Monitoring
An Operations Perspective
BP Confidential
2
Key Questions
Why is riser monitoring important?
What can we do with the data?
What do we need to consider for future systems?
BP Confidential Greater Plutonio Overview
3
3
Greater Plutonio Subsea Layout
Control Umbilicals
12” Service Line
14” Northern Water Injection line
12” Southern Water Injection line
12” Gas Injection line
Riser Tower
12” Northern Production Line
12” Southern Production Loop
Offloading Buoy
DWSSM
S1
S3
S4 S2
N2
N1
N3 N4
BP Confidential The Riser Tower Structure
4
BP Confidential
5
Buoyancy Tank Design
• HRT designed with 814 Te buoyancy
• Buoyancy tank comprises 36 compartments.
• Four ballast compartments are filled with treated fresh water.
• HRT is designed to operate with one compartment flooded. Two flooded compartments represents a shut-in condition.
• Ballast tanks are included as mitigation of flooding threat
• Flooding of peripheral and central compartments will result in loss of tension of 400kN and 800 kN respectively.
• Flooding of compartments…
− Tension monitoring primary means of detection
− Influence of environment and operating conditions impacts attitude, bending, and global position – prevents immediate identification.
BP Confidential
Riser Tower Monitoring Equipment
Tension Monitoring through Linear Variable Differential Transformers (LVDTs)
Attitude monitoring (6 Degrees of Freedom, IXSEA Octans)
Position monitoring (Transponder, Compatt5 Sonardyne
Hybrid Riser Tower Monitoring System
Buoyancy Tank Integrity known
Core Pipe Integrity known
Offset between FPSO and top of riser tower known
Riser Tower monitoring gives: • Assurance that it is safe to continue operating • Builds a picture of the tower’s behaviour for operating
life
BP Confidential Riser Tower Response to Operating Conditions
7
BP Confidential Detecting a Problem
• 2 key areas of concern:
− Catastrophic / sudden failure
− Slow leak
• Sudden failure will be detected by alarms, including dynamic tension alarm
• Slow leak can be seen in long term trends
8
Upp
er Te
nsio
n
BP Confidential Detecting a Problem
9
BP Confidential Obtaining the Data
• Old System:
• New System:
10
Data Offshore
Copied to CD
CD hand carried to
UK
CD posted to USA
Data Processed
Processed data sent to IM contractor
Quarterly Report issued
Data Offshore
Selected channels to ProcessNet
Data to USB stick
offshore
Offshore upload to
Sharepoint
IM contractor accesses data
BP Confidential Monitoring System Design Lessons Learned
• The monitoring system is only as good as the data you get back from it!
• Design of a monitoring system should include thought into methods for obtaining the data and what the data will be used for
• Response to offshore alarms is hindered when engineers on the beach do not have access to the data
• Redundancy and retrievable equipment is important for long term operability
• Operations input into projects system design is valuable
11
BP Confidential Conclusions
Why is riser monitoring important?
• Understanding of the integrity - the riser tower is a complex system
• Safe ongoing operations, including possible field life extension
• Possible use for future design optimisation
What can we do with the data?
• Detect faults – catastrophic failures and slow degradations
• Calibrate models – useful for predicting tower behaviour
What do we need to consider?
• Data, data, data! If you’re producing good data, engineers need to be able to see it
• Redundancy and maintainability
• What are you actually looking for? A monitoring system is just one possibility…
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Leah Regel
Riser and Flowline Engineer
BP International Centre for Business and Technology
Chertsey Road
Sunbury
Middlesex
TW16 7LN
Acknowledgments: Brian O’Keefe, Woodgroup Kenny Soma Maroju, BMT
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