Riser and wellhead monitoring for improved
offshore drilling operations Gullik A. Jensen, PhD
Product manager Riser Management System
Kongsberg Oil & Gas Technologies
E-mail: [email protected]
CeSOS Highlights and AMOS Visions Conference,
Trondheim, May 27th 2013
Agenda
• Introduction
– Offshore drilling with riser
– On the riser and the riser joints
– On damage and consequences
• Operational monitoring
– Instrumentation of the riser
– Monitoring of key parameters
• Decision support and guidance control
– Controlled parameters and objective
– Guidance control
• Wellhead fatigue instrumentation
– A current project by Kongsberg
• Summary
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The KONGSBERG Riser Management Systems (RMS)
Integrity of drilling riser based on monitoring flex-joint and ball joint angles Advisory system for maintaining control of critical riser and wellhead parameters during varying environmental conditions
• Delivered with Motion Reference Unit
instruments (MRU 2) from Kongsberg Seatex
• Developed in cooperation with
Kongsberg Maritime (integrated with K-POS dynamic positioning system)
• More than 75 systems sold
Drilling Risers Riser Management Solutions
Workover Risers Riser Management Solutions
BOP WH Fatigue Condition Monitoring
Instrumentation
Integrity of workover risers based on monitoring strains in tension joint and stress joint Advisory system for maintaining control of critical riser and wellhead parameters during varying environmental conditions
• Instrumentation based on strain
gauges delivered by Force Technology
• 11 systems sold
Integrity of Wellheads
Monitoring BOP and riser motions and strains to asses wellhead fatigue and better understanding of structural behaviour
• Redundant system to secure stable,
reliable data access
• Online data distribution to the rig and to operation centres onshore
• Delivered by KOGT with Kongsberg
Maritime and MultiControl as sub-contractors
• Two systems delivered.
Offshore drilling with riser ...a quick introduction
Offshore drilling is performed from floating
drill ships or drill rigs
Courtesy of Seadrill Courtesy of Saipem
• Equipped for drilling subsea wells.
• Uses dynamic positioning system (DP) to maintain position (Kongsberg Maritime)
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A riser is a conduit that provides a
temporary extension of a subsea oil well to a
surface drilling facility.
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The drilling riser is made up of many joints,
some with special purposes.
Wellhead
Lower flex joint
Upper flex joint
Standard joint
Telescopic joint
Stack
(BOP)
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The riser may be subject to great loads in
bad weather conditions
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This video is from YouTube
The riser flex-joints are one of the mot
important parameters for drilling operations
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This video is from YouTube
Damage to the riser and wellhead can be
detected and avoided with riser monitoring
Key seating
Excessive flex joint angles
Rupture
Excessive loads or fatigue
Buckling
Insufficient top tension
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The environmental damage from an
uncontrolled blowout is extremely high
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There are three objectives to keep in mind
during riser operations.
Safe operation…
…deals with conduction the operation within operation
limits to ensure that undesirable events does not happen.
This is done by monitoring critical parameters.
Operation optimization…
… deals with changing the operational conditions to
reduce the risk of undesirable events happens. This is
done by advices and decision support.
Integrity management…
… deals with tracking the time in use of the riser
equipment and the estimation of the wear and tear,
including fatigue. This is used in inspection planning and
remaining joint lifetime estimation.
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Operational monitoring … ensure safe operation and avoid damage.
Real-time sensor data is collected from
sensors and external systems
External systems
DP System
Drilling Control System
Tensioner System
BOP Control System
Riser instrumentation
Inclinometers
Strain gauges
The integrity of the whole riser is monitored
by monitoring critical riser parameters
Flex joint angles
Strain and tension
in selected cross-
sections
Telescopic joint
stroke
Top tension
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Decision support and guidance control … optimize operation, reduce the risk of damage.
Critical parameters for operation can not
directly be controlled
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Upper flex joint angle
Tension
Lower flex joint angle
Telescopic joint stroke
Vessel position
(DP system)
Top tension
(Tensioner system)
Controlled
parameters
Critical
parameters
The control objective is to minimize the
flex-joint angles by repositioning the vessel
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Optimum vessel
position
Upper flex-joint
angle safe zone
Lower flex-joint
angle safe zone
Positioning control system hierarchy
Actuator control
Drilling vessel and riser Environment Sensors
DP Control
Control Allocation
Human Operator
RMS
Low Level Control
Intermediate Level Control
High Level Control
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Wellhead fatigue … instrumenting the BOP to determine wellhead fatigue.
The estimated wellhead remaining fatigue
life is short for wells in mature fields
Challenge
• The reaming fatigue life of many wellheads are very short.
• The estimation of fatigue is conservative since the true loads on the wellhead is not known.
Objective
• Calculate the wellhead fatigue in real time based on the rig actual motion and riser / BOP behaviour
• The purpose is to establish a standard for instrumentation for floating mobile drilling rigs
• Reduce uncertainty in global analysis by doing actual measurements of the BOP motions
• To achieve a better understanding of the actual risk level.
Solution
• Instrument the BOP to get as much data about motions and loads as possible.
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Two drilling rigs in opposite ends of the fleet
regarding equipment and size were chosen
Courtesy of Odfjell drilling Courtesy of Transocean
DeepSea Bergen (Odfjell Drilling)
• Year entered service: 1983
• Max water depth: 450 m
• Displacement: 27,209 m/t
• Positioining system: Mooring
• BOP: NL Shaffer
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Transocean Spitsbergen (Transocean)
• Year entered service: 2009
• Max water depth: 3000 m
• Displacement: 64,500 m/t
• Positioning system: Kongsberg DP class 3
• BOP: Cameron
Subsea system topology
• Strain measurements
– Bottom of BOP
– LMRP above the flex-joint
• Motion sensors (MRU5+)
– Bottom of BOP
– LMRP below the flex-joint
– LMRP above the flex-joint
– Below the upper flex-joint
– Above the upper flex-joint
• Full redundancy
– All sensors
– All communication
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Instrumenting the bottom of the BOP
The spool piece directly above the wellhead connector was chosen for instrumentation.
Motion sensor Kongsberg MRU5+
Battery pack Strain sensor module
Communication module
All pictures is the property of Kongsberg Oil & Gas Technologies
Instrumentation on LMRP
25
Motion sensor Kongsberg MRU5+
Strain sensor module
Communication module
Battery pack
All pictures are the property of Kongsberg Oil & Gas Technologies
The measured data is transmitted to land in
real-time for further processing
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Example of a history plot. Example of a control dashboard.
All pictures are the property of Kongsberg Oil & Gas Technologies
Summary … on riser and wellhead monitoring for drilling operations
• The critical parameters during a drilling operation are:
• Upper flex-joint angle,
• Lower flex-joint angle,
• Telescopic joint stroke,
• Top tension.
• Exceeding operation limits for critical parameters may cause damage.
Introduction
• Real-time sensors used with an advanced model provides the states of the riser system to the operator.
• Critical parameters are continuously watched and action taken if operation limits are exceeded.
• The purpose is to avoid damage.
Operational monitoring
• Optimize the operation and reduce the risk of undesired events.
• Vessel repositioning can reduce the critical parameters.
• The purpose is to assist the operator and reduce the risk of damage.
• The optimization may also reduce the vessel down time.
Advices and decision support
• Instrumentation of the riser and BOP to measure loads on the wellhead.
• Calculate the wellhead fatigue in real time based on the rig actual motion and riser / BOP behaviour.
Wellhead fatigue
kongsberg.com