1. 18th Nov 2009
Culzean HPHT:
Lessons Learnt From Maersk Oil UK’s 1st HPHT Exploration Well
&
Issues Related to Appraisal Planning
Jim Manson, Culzean Drilling & Completion Team Leader
IQPC HPHT Conference

2. 22 June, 2016
2
Presentation Outline
• Culzean Prospect Background Information
• Culzean Exploration Well
• Well Design Issues
• Planning Issues
• Results - High Level Summary & Lessons
Learnt
• Culzean Appraisal Well Planning
• Appraisal Well Challenges & Objectives
• Appraisal Well Design
• Appraisal Keeper Wells?
• Culzean Development Well Planning Issues

3. 22 June, 2016
3
Presentation Outline
• Culzean Prospect Background Information
• Location, Geology, History Timelines, Challenges
• Culzean Exploration Well
• Well Design Issues
• Planning Issues
• Results - High Level Summary & Lessons Learnt
• Culzean Appraisal Well Planning
• Appraisal Well Challenges & Objectives
• Appraisal Well Design
• Appraisal Keeper Wells?
• Culzean Development Well Planning Issues

4. 22 June, 2016
4
10 km
242km from Aberdeen to Culzean
Heron
Marnock
Elgin, Franklin &
Shearwater
Jackdaw
NO.
UK.
Culzean Prospect Location
Culzean Prospect:
49.99% Maersk Oil NS UK Ltd
16.9% ENI UK Ltd
17.1% Nippon UK
16% BP

5. 22 June, 2016
5HPHT Province with offset fields
(After Winefield et.al. 2005)
Culzean
22/25a-9z
O/P circa 6500psi
Temperature ~380 degrees F

6. 22 June, 2016
6
Culzean Seismic Section West to East
Source: United Kingdom Discovery Digest. Special thanks to CGG Veritas

7. 22 June, 2016
7
Culzean Prospect Timelines
• Exploration well 22/25a-1 drilled 1986 by BP
• Dormont until operatorship transferred to Maersk Aug 05
• Maersk Conceptual Planning/Discussions from 2002
• Provisional Casing Design – June 05
• Long Leads ordered May 06
• Exploration Well, 22/25a-9/9Z
• Spud - May 08
• P& A – Dec 08
• Drilled utilising Ensco 101 HDJU Rig
• Appraisal Well Planning Started Jan 09
• Planned Two Well Appraisal Campaign
• 18 month planning phase
• Planned Spud Appraisal 1 – Jul 10

8. 22 June, 2016
8
Culzean Exploration Well Challenges
• Limited offset wells – 22/25a-1 well drilled in 1986 by BP. Littered by drilling
problems, failed to reach TD. Extensive well control issues , including classic
wellbore breathing. Limited detailed information on this well.
• High geological uncertainty.
• High Pressure Uncertainty - BHP Range 17.0 ppg to 18.5 ppg emw
• ~380 deg F BHT.
• Drill close to crest - Narrow window between PP & FG - potentially un-drillable!
OVERALL CHANCE OF DRILLING SUCCESS =53%
Breakdown of 47% Drilling Risk of Failure:
Risks 1 to 3 – Potentially too narrow and un-drillable drilling window
1. Aquifer Overpressure Greater than Predicted = 20%
2. Sand above the target reservoir =2.5%
3. Fracture Gradient Less than Estimated =25%
4. Problematic Gas in Hidra =10%

9. 22 June, 2016
9
Presentation Outline
• Culzean Prospect Background Information
• Culzean Exploration Well
• Well Design Issues
• Well Objectives
• Non DST/Finder Well Rational
• Well Design Options
• Planning Issues
• Results - High Level Summary & Lessons Learnt
• Culzean Appraisal Well Planning
• Appraisal Well Challenges & Objectives
• Appraisal Well Design
• Appraisal Keeper Wells?
• Culzean Development Well Planning Issues

10. 22 June, 2016
10
Culzean Exploration Well
Well Objectives
• Drill a safe and incident free well.
• Reach well planned TD.
• Penetrate all reservoir prospects.
• Successfully log all reservoir prospects.
• In success case, MDT pressures and samples over reservoir
prospects.
• No Coring
• No DST to be carried out.
• P&A.

11. 22 June, 2016
11
Culzean Exploration Well
Non DST/Finder Well Exploration Rational
• Chances of Exploration Success?
• Extra cost to include DST considerations in casing design.
• Final hole size drives well design.
• HPHT DST standard tools – 5” OD
• Test tools as close to perforations as possible ( well kill volumes & complexity if
testing with a drilling liner)
• Thus preferred 8 ½” hole x 7” liner at TD for DST well.
• Heavier casing design required – HPHT Heavy vs HPHT Light
• Increased loads – Increase casing specification – Increased costs (10 ¾” -
9 7/8” up to £1.0m more, 13 5/8” or 14” vs. 13 3/8”)
• DST Long Leads ~£1m
• Contingency tie-back string ~ £1m.
• DST planning – manpower and hours
• Total Cost Differential ~ £8m- £10m less for Non/DST Finder
“Light” design

12. 22 June, 2016
12
Culzean Exploration Well
Non DST/Finder Well Exploration Rational (Cont’d)
Worked Example:
Eg. Chance of Exploration Success - 1 in 7 or 14.3%
Expected Cost to go to Development?
Conclusion: Culzean Exploration - Non DST, P & A
HPHT Light
£49m/well
HPHT Heavy
£59m/well
HPHT Light/Finder
(£M)
HPHT Heavy
(£M)
7 Exploration Wells 343 413
Test Exploration Well 0 19
1 Appraisal Well 59 49
Test Appraisal Well 19 0
Total To Go To Development 421 481
60Cost Saving with Finder Exploration Concept

13. 22 June, 2016
13
22 June, 2016
13
Culzean Exploration Well
Design Options : HPHT “Heavy” vs HPHT “Light”
36” x 26” hole
26” x 20” Conductor
set @ 3000ft
16” or 17 ½” hole
13 5/8” Intermediate
casing set
~ 11,000ft to ~12,000 ft
12-1/4” hole
10 ¾” x 9 7/8” Production
casing set
~14,000ft to ~15,000ft
8-1/2” hole
7” Test liner set
@ TD
~17,000ft
HPHT “Heavy” HPHT “Light”
36” x 26” hole
26” x 20” Conductor
set @ 1900ft
16” or 17 ½” hole
13 3/8” Intermediate
casing set
~ 5,000ft to ~6,500 ft
12-1/4” hole
9 7/8” Production casing set
~13,500ft to ~14,000ft
TD in 8 1/2” hole

14. 22 June, 2016
14
22 June, 2016
14
Casing Setting Depths - Contingency
8-1/2” hole
7” Drilling liner
set @
~14,400ft
5-7/8” hole
4 ½” Test liner
set @ TD
HPHT “Heavy”
16” or 17 ½” hole
13 5/8” Intermediate
casing set
~ 11,000ft to ~12,000 ft
12-1/4” hole
10 ¾” x 9 7/8” Production
casing set
~14,000ft
HPHT “Light”
12-1/4” hole
9 7/8” Production casing set
~13,500ft to ~14,000ft
8-1/2” hole, 7 5/8” Drilling
liner
6 5/8”” hole
6” by 7 5/8” SET , then
6” hole
TD in 6 5/8” or 6” hole
Culzean Exploration Well
Design Options : HPHT “Heavy” vs HPHT “Light”

15. 22 June, 2016
15
Culzean Exploration Well
HPHT “Heavy” Design
Pro’s
• 12 ¼” hole can be drilled deep into PTZ
• Increased chance of higher FG at 9 7/8” shoe and TD in 8 ½”
hole.
Con’s
• Slower to drill, heavier and more expensive design
• Drilling hard abrasive Palaeocene & chalks in slower 16” or 17
½” hole.
• Increase volume OBM cuttings for containment

16. 22 June, 2016
16
Exploration Well Planning
HPHT “Light” Design – Chosen Exploration Well Design
Pro’s
• Slimmer, faster, cheaper design
• Drilling hard abrasive Palaeocene & chalks in quicker 12 ¼” hole.
• WBM 17 ½” section.
• Possible further expandable liner option available just to reach TD
objectives.
• Possible further optimisation of deletion of separate 20” casing string.
Con’s
• Due to weak Palaeocene/Tor formations, 12 ¼” hole cannot be drilled
deep into PTZ.
• Less chance of TD in 8 ½” hole.
• Not a problem – no DST or coring required.

17. 22 June, 2016
17
Presentation Outline
• Culzean Prospect Background Information
• Culzean Exploration Well
• Well Design Issues
• Planning Issues
• Results - High Level Summary & Lessons
Learnt
• Culzean Appraisal Well Planning
• Appraisal Well Challenges & Objectives
• Appraisal Well Design
• Appraisal Keeper Wells?
• Culzean Development Well Planning Issues

18. 22 June, 2016
18Exploration Well Planning
Planning
• Maersk HPHT Experience
• 1st Maersk UK HPHT Exploration well.
• Gain knowledge & experience.
• Hire/Recruit
• Networking: HPHT Operators Forum, Conferences, Contacts?
• Lead times – realistically >2 years, or more
• G & G review prospect – ? years
• Detailed casing/design iterations w/ G&G – 1year
• Lead time on bespoke equipment – 1 year.
• Integrated/Interdisciplinary Approach Essential.
• Service Providers into Team early.
• Management Of Stakeholders?
• Partners, Management, All Disciplines, HSE, Well Examiner
• Alignment, Inform, Draw on HPHT experience

19. 22 June, 2016
19
Presentation Outline
• Culzean Prospect Background Information
• Culzean Exploration Well
• Well Design Issues
• Planning Issues
• High Level Summary & Lessons Learnt
• Culzean Appraisal Well Planning
• Appraisal Well Challenges & Objectives
• Appraisal Well Design
• Appraisal Keeper Wells?
• Culzean Development Well Planning Issues

20. 22 June, 2016
20
Culzean Exploration Well - High Level Summary
Highlights
• Challenging Prospect -53% Chance of Drilling Success @ Crestal Location.
• Achieved planned well TD, meeting ALL Well Objectives.
• Close to not achieving objectives through PTZ!
• Narrow PPFG window , Utilised contingency 7 5/8” Liner to open up.
• Milestones:
• 9 7/8” Casing on depth, Well Cemented, Coped with High PP on bottom and loss
zone above.
• 7 5/8” , As Above.
Lowlights
• 8 ½” Kick – Poor Offshore Practices and decision making – should have
been better handled.
• 17 ½” Hole – 13 3/8” Casing stood-up, section re-drill required.

21. 22 June, 2016
21
Just some of the PPFG Models !
Depth
Pressure (ppg)
Pore
Pressure
Forties
Lwr. Cretaceous
Top Reservoir
Fracture
Gradient
Point of Note:
HPHT Geological Surprises
• Expect surprises.
• Multiple PPFG Models
• Plan for the extremes of PPFG –
cover all the bases!
• Build in maximum flexibility in
well design to achieve
objectives.
• Gathered some information,
but still many unknowns on
prospect.
Culzean Exploration Well

22. 22 June, 2016
22
Presentation Outline
• Culzean Prospect Background Information
• Culzean Exploration Well
• Well Design Issues
• Planning Issues
• Results - High Level Summary & Lessons
Learnt
• Culzean Appraisal Well Planning
• Appraisal Well- Challenges &
Objectives
• Appraisal Well Design
• Appraisal Keeper Wells?
• Culzean Development Well Planning Issues

23. 22 June, 2016
23
Appraisal Well Planning
Appraisal Well -Challenges & Objectives
• Challenges
• Crestal Locations
• Still with major geological uncertainty
• one appraisal, one exploration well.
• Seismic formation top accuracy.
• Pore pressure uncertainty
• Aquire sufficient key data for ascertaining economic
development
• DST, Cores, Fluid Data, Log Data
• Sufficient data to proceed to project sanction.
• Aquire sufficient data for detailed development design.

24. 22 June, 2016
24
Presentation Outline
• Culzean Prospect Background Information
• Culzean Exploration Well
• Well Design Issues
• Planning Issues
• Results - High Level Summary & Lessons
Learnt
• Culzean Appraisal Well Planning
• Appraisal Well Challenges & Objectives
• Appraisal Well Design
• Appraisal Keeper Well?
• Culzean Development Well Planning Issues

25. 22 June, 2016
25
Appraisal Well Design
• Exploration Well HPHT ”Light” Design & 12 ¼” TD
• Achieved ”All” well objectives, still had one more contingency hole size
available.
• However, went too deep into PTZ w/ shallow 13 3/8” shoe.
• Weak zone(s) in Paleocene (Forties) and/or top Tor.
• Design incompatible w/ drive 9 7/8” shoe as deep as possible into PTZ.
• Exploration Well - Needed Contingency Liner Option to
Negotiate PTZ.
• Appraisal well - DST Required from multiple zones
• Conclusion: HPHT ”Heavy” Design required with deep set 13
5/8” Casing.
• Optimum setting depth for 9 7/8” shoe? As deep as possible,
preferably the Valhall.
• 13 5/8” shoe depth? To facilitate above.

26. 22 June, 2016
26
22/25a-9z Fracture Pressure in Tor
ft/hr
0.2 2 20 200
ohmm
200 0
low resistivity
high ROP
higher porosity
weaker formation

27. 22 June, 2016
27
22 June, 2016
27
Culzean Exploration Well
Design Options : HPHT “Heavy” vs HPHT “Light”
36” x 26” hole
26” x 20” Conductor
set @ 3000ft
16” or 17 ½” hole
13 5/8” Intermediate
casing set
~ 11,000ft to ~12,000 ft
12-1/4” hole
10 ¾” x 9 7/8” Production
casing set
~14,000ft to ~15,000ft
8-1/2” hole
7” Test liner set
@ TD
~17,000ft
HPHT “Heavy” HPHT “Light”
36” x 26” hole
26” x 20” Conductor
set @ 1900ft
16” or 17 ½” hole
13 3/8” Intermediate
casing set
~ 5,000ft to ~6,500 ft
12-1/4” hole
9 7/8” Production casing set
~13,500ft to ~14,000ft
TD in 8 1/2” hole

28. 22 June, 2016
28
22 June, 2016
28
Casing Setting Depths - Contingency
8-1/2” hole
7” Drilling liner
set @
~14,400ft
5-7/8” hole
4 ½” Test liner
set @ TD
HPHT “Heavy”
16” or 17 ½” hole
13 5/8” Intermediate
casing set
~ 11,000ft to ~12,000 ft
12-1/4” hole
10 ¾” x 9 7/8” Production
casing set
~14,000ft
HPHT “Light”
12-1/4” hole
9 7/8” Production casing set
~13,500ft to ~14,000ft
8-1/2” hole, 7 5/8” Drilling
liner
6 5/8”” hole
6” by 7 5/8” SET , then
6” hole
TD in 6 5/8” or 6” hole
Culzean Exploration Well
Design Options : HPHT “Heavy” vs HPHT “Light”

29. 22 June, 2016
29
Appraisal Well Planning
HPHT “Heavy” – Chosen Appraisal Design
Pro’s
• 12 ¼” hole can be drilled deep into PTZ
• Thus increased chance of FG at 9 7/8” shoe enabling TD in 8 ½” hole.
• Implications of 7” Drilling Liner
• DST well kill distance from perforations.
• DST well kill volumes.
• DST multiple zone testing – mill packer or re-use.
• 5 7/8” hole – limitations on logs , smaller core- limitations on modelling
Con’s
• Slower to drill, heavier and more expensive design
• Drilling hard abrasive Palaeocene & chalks in slower 16” or 17 ½”
hole.
• Increase volume OBM cuttings for containment

30. 22 June, 2016
30
Presentation Outline
• Culzean Prospect Background Information
• Culzean Exploration Well
• Well Design Issues
• Planning Issues
• Results - High Level Summary & Lessons
Learnt
• Culzean Appraisal Well Planning
• Appraisal Well Challenges & Objectives
• Appraisal Well Design
• Appraisal Keeper Wells?
• Culzean Development Well Planning Issues

31. 22 June, 2016
31
Culzean Appraisal - Keeper Well?
Prize?
• ~£80m/appraisal well , P & A ?
• + ~£80m/development well = £160m
• Keeper – Potential to save £15m to £30m/development well?
Issues?
• Assumed dry tree development.
• No fully qualified & field proven HPHT MLT equipment.
• Integrity at MLT? ( multiple use, MTM seal, Incaloy material, verticality etc.)
• Alternative Shallow or Deep Tie-back options?
• Tie-back operations - Complex, multiple operations. Poor success in past. High
risk of failure.
• Uncertainty on appraisal prospect – Size? Shape? Variability?
Compartmentalisation? Upside? Downside?
• Appraisal surface location drives platform location?
• High risk of non-use , and potential high later abandonment costs.
• Early installation of wellhead jacket ? – time & cost!
Conclusion?
• Tie-back Low Chance of Success, High Chance of Cost Over-Run
• P & A appraisal well.
• Review Keeper options for further potential appraisal wells.
Prize?
• HPHT Mudline tie-back? Alternative Approach? Service Sector?

32. 22 June, 2016
32
Presentation Outline
• Culzean Prospect Background Information
• Culzean Exploration Well
• Well Design Issues
• Planning Issues
• Results - High Level Summary & Lessons
Learnt
• Culzean Appraisal Well Planning
• Appraisal Well Challenges & Objectives
• Appraisal Well Design
• Appraisal Keeper Wells?
• Culzean Development Well Planning Issues

33. 22 June, 2016
33
Development Well Planning Issues
• Timelines
• Earliest spud of development wells on critical path to 1st
hydrocarbons
• Depletion drilling challenges?
• Earliest installation of wellhead jacket?
• Concurrent development planning with appraisal
drilling.
• Still many unknowns
• Size, Productivity, Homogeneity, Connectivity
• Fluids
• Conceptual Casing & Completion Designs
• All the issues & input parameters
• HPHT Light vs. HPHT Heavy!
• Knowledge & Experience?

34. 22 June, 2016
34
Culzean HPHT:
Lessons Learnt From Maersk Oil UK’s 1st HPHT
Exploration Well
&
Issues Related to Appraisal Planning
Jim Manson
Culzean Drilling & Completion Team Leader
ANY QUESTIONS?