Helix Well Abandonment State of the Nation Neil Greig · Helix – State of the Nation ......
Transcript of Helix Well Abandonment State of the Nation Neil Greig · Helix – State of the Nation ......
Helix – State of the Nation
Rev 0 St.Andrews Decom Conference 18th & 19th November 2015
Well Abandonment Neil Greig
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Discussion topics
Case study examples of batching and campaigning
Challenges
Successes
What could we do differently?
Collaboration (Batching and Campaigning)
– Between us and other parties
– Operator to Operator
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Subsea P&A - types of activities
Work completed before a rig campaign Prep Abandonment
Permanent Plug and Abandonment
Abandonment of suspended E&A wells
Reservoir isolation
Cat 2 or Cat 1 wells
All of these activities are ideal for a batched campaign approach
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Background to case studies
Prep abandonment conducted when:
– Technical issues e.g.
• Fatigue, Scale, TAC, Parted tubing
– There are clear time savings
• Removing work from the rig
Permanent P&A
– Rigs are the accepted method
E&A wells
– Some examples of
collaboration in 2015….
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Case History Prep
Work on 25 live wells
1. Gain access
2. Bullhead to Seawater/PT
3. Gather information
4. Set Plug below packer
5. Tubing cut above packer
6. Set plug below the hanger
(Switch to Annulus)
1. Set BBO Packer/Pressure Sub
in Annulus Tailpipe
2. Tree recovered or left for future
rig campaign
3. Disconnect flowlines
Live wells, 4 fields, 7 Campaigns spanning
2009 to 2014
Over 25 wells in the CNS
Objectives Met
• Integrity tested wells & removed Tree
Caps
• Bullheaded tubing contents to formation
with TSW
• Entered wells to ascertain condition
and ability to install plugs
• Installed lower plug for reservoir
isolation
• Punched &/or cut tubing
• Installed upper plug
• Reconfigured and plugged annulus
• Installed ROV interface panels as
required
• Disconnected flowlines where possible
• Removed XT’s where applicable
Advantages for the Rig?
-Access issues removed
-Some downhole work completed
-No LRP/EDP (saves time and deck
space)
-Rig can mobilise with BOP and a
defined, tailored workscope
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Reservoir Isolation
Thru’ Tubing abandonment process
Campaign of 12 wells with 4
operators in 2000
Set cement plugs in the tubing
Moved away from this approach
Gauge cables
Annulus cement verification
Perhaps an opportunity for more
collaboration between the operators
and the OGA?
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E&A (Cat 1 & Cat 2) wells in 2015
Category 2 wells (A and B annulus)
– Operator B (3qty x Cat 2.2)
– Operator B (1qty x Cat 2.1)
Category 1 wells (Wellhead severance)
– Operator A (12qty)
– Operator B (1qty)
– Operator C (1qty)
– Operator D (1qty)
Total of 19 wells
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What were the challenges?
“Lack of information is the biggest
challenge” They are old wells, needing divers, no history, difficult to
access, weakened wellheads, unknown downhole conditions
• TAC?
• Parted Tubing?
• Corroded Tubing?
• Scale?
• DHSV or Tree Valves?
Requires extensive planning Project Management
3rd party involvement
Robust procedural development
Review
Scheduling
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Success factors
Challenging conditions-not just the well
Overcame the well access issues
Gathered precious information
Plugged the wells to allow for rig arrival
Rig doesn’t need close cover DSV support
Saved significant time and cost
Reduced the environmental risk
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What could be changed?
The sequence of the P&A prep work could be made more
efficient by batching
– Take off all the Tree Caps in one go
– Do all the tubing downhole work in one configuration
– Same for the annulus
(A caveat to this is well control)
But there’s more to this in the next section
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Why batch and campaign?
Good campaigning?:
Operator A pays for mob, spread, demob for Cat 2 equipment
and Cat 1 equipment for ONE WELL!
Then Operator B does the same 2 months later
And operator C follows later still………..
And batching?:
Operator contracts a rig to PPA the well using BOP, recovers
BOP to recover the HXT, then runs severance equipment then
has to re-run the BOP on the next well and so on
Pass control of the schedule to OGA?
Batch the work so the rig only does the plugging and leave
the Tree recovery etc to LWI
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Examples of Collaboration
Collaboration between operators is rare
i. In 2015 19qty Well Abandonments (Cat 2; Cat 1)
• Operators A&B* shared equipment
• As did C&D*
ii In 2000 12qty Live well abandonments between 4
operators*
* All with their own contract challenges
Reduced mob
Increased efficiency
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Collaboration (cont.)
OIS and WellOps have been trying to improve Operator 2
Operator collaboration for years
Various different contract models tried with little uptake
When we do it, it’s only for short periods yet there are hundreds
of wells in the UKCS
We’ve heard from all sides that we want more of this but for
some reason it’s not happening…