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

22 June, 2016

2Presentation 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

22 June, 2016

3Presentation 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

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

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

22 June, 2016

6Culzean Seismic Section West to East

Source: United Kingdom Discovery Digest. Special thanks to CGG Veritas

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

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%

22 June, 2016

9Presentation 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

22 June, 2016

10Culzean 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.

22 June, 2016

11Culzean 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

22 June, 2016

12Culzean 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

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

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”

22 June, 2016

15Culzean 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

22 June, 2016

16Exploration 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.

22 June, 2016

17Presentation 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

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

22 June, 2016

19Presentation 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

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.

22 June, 2016

21

Just some of the PPFG Models !

Depth

Pressure (ppg)

Pore

Pressure

Forties

Lwr. CretaceousTop 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 June, 2016

22Presentation 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

22 June, 2016

23Appraisal 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.

22 June, 2016

24Presentation 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

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.

22 June, 2016

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22/25a-9z Fracture Pressure in Tor

ft/hr

0.2 2 20 200

ohmm

200 0

low resistivity high ROPhigher porosity weaker formation

22 June, 2016

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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

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”

22 June, 2016

29Appraisal 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

22 June, 2016

30Presentation 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

22 June, 2016

31Culzean 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?

22 June, 2016

32Presentation 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

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?

22 June, 2016

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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?