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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Collaboration

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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…

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END