Culzean 22/25a-H5(8) – HPHT Exploration Well Plan with MPDJim MansonHPHT OPERATORS FORUM , May 2008

22 June 2016Drilling Department

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Culzean, 22/25a-H(8) Location

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Culzean, 22/25a-H(8) Location

Culzean Location

22/25b-2 12.3km NW

22/25a-1 3.8km NNE, BP, 1986

22/25b-4 6.2km WSW (Egret)

22/30a-2 7.6km SW (Heron), Shell, 1988

22/30a-6 8.1km SW (Heron), Shell, 1989

22/24b-8 13.8kn NW (Marnoch)

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Regional HPHT

6000

8000

10000

12000

14000

16000

18000

200 250 300 350 400

Temperature Degrees FP

ressu

re (

psia

) Central Graben HPHT HTHPUltra HPUltra HTLinear (Ultra HP)Linear (Ultra HT)

Culzean 5700psi O/P

At top Reservoir

13,290 psi, 17.5 ppg EMW

Culzean 6800psi O/P

At top Reservoir

c. 14,430 psi, 18.3 ppg EMW

Marnock

& Skua

Erskine

Heron

Egret

Commander

Condensate (could be oil)

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Culzean Seismic Section North to South

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Culzean Geological Prognosis & Well Design26x20” @ 1900ft BRT

1

1

Section 1 : Sea bed to UC10 / FCS17

Performance Section

36” x 26” Hole Section / 26” x 20” Conductor36” TD at 555ft / 26” TD at 1900ft MDBRT (Nordaland Group)

17-1/2” Hole Section / 13-3/8” Casing17-1/2” TD at 6500ft MDBRT (Horda Formation)

Drilled with Ultradril – Water based mud system – 11ppg (No requirement for Skip & ship)

12 ¼” Section -Performance BHA(s)Expected leak-off at 13-3/8” csg shoe – 15.7ppg

TD in Upper Cretaceous (UC10/FCS17) approx 13,720ft

Drilled with Versatherm – OBM – 13.2ppg (requirement for Skip & ship)

MWD / LWD – Directional / GR/RES only

Well Architecture & ObjectivesNo Well Testing or CoringHPHT Light Well Design vs HeavyLWD Heavy / Wireline LightPlexus 18 ¾” , 15M, Pos-Grip WellheadEnsco 101 Rig

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26x20” @ 1900ft BRT

2 2

Section 2 : UC10/FCS17 to Kimmeridge ClayOnset of Transition zone unknown, top Hidra to ValhallAim to set as deep into transition as possible, hopefully Valhall, but could be earlier. From UC10/FCS17 to (Rodby / Sola / Valhall)– Maximum mud weight 14.5ppgMWD / LWD – Directional / Quad Combo (GR/RES/DN/SON) – RES at bit included.Use of biostratigraphy for “navigation”Real-time Pore Pressure analysis (KSI)9-7/8” , 68.9 ppf , VM110SS, Vam Top casing

Main Challenges of SectionGetting 9-7/8” casing deep enough into the transition zone to achieve fracture gradient for 8-1/2” hole section.

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26x20” @ 1900ft BRT

3

3

Section 3 : Top Kimmeridge Clay to TDIf LOT < 18.7ppg contingency to set 7-5/8” liner.Use MPD system when pore pressure is known. Dry-Hole TD – 15,121ft / Success TD – 16,576ft MDBRTReal-time Pore Pressure analysis (KSI) – Chemostrat analysisMWD / LWD – Directional / Quad combo (GR/RES/DN/SON)Inclusion of Geo-tap in BHA – depending on actual temperatures in base 12-1/4”6” expandable contingency with 5 7/8” Hole.

Main Challenges of 8 1/2”/6 ¾” Hole sections

Well control problems possible if pressures higher than most likely maximum.Mud losses. Wellbore breathing, narrowing of pressure window, failure to achieve TD objectives. Differential sticking across any permeable formations – especially in the Triassic Formations.Tool failures due to excessive temperatures.

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Pore Pressure, Fracture Gradient and Mud Weight

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Culzean Prospect Milestones

Acreage bought 2003

Target location & PPFG Modelling 2004/5

Provisional Casing Design – June 05

Long Leads ordered ( eg. 9 7/8” casing) May 06

Ensco 101 on contract August 07

Spud May 2008

Rig Preparations

Rig Inspections & Audit of Well Control Equipment for HPHT

Rig Upgrades – minimal (Tension system, MGS)

Managed Pressure Drilling (MPD) – spool pieces & tie-ins and electrical work.

Crew Preparation

Maersk Training HPHT Course prepared and run

Culzean Specific Offsite HPHT Training and Well Preparation Seminars

Culzean Specific Well Control Simulator Exercises

HPHT Well Control Coach

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Managed Pressure Drilling (MPD)

Typical HPHT Scenario

Narrow margin between pore pressure and fracture pressure

Pressure cycling on well can lead to losses on drilling ECD and gains when static with ECD removed –WELLBORE BREATHING.

SIGNIFICANT Loss of time and potential loss of pressure operating window.

Potential Solution:

Management of mud weight, ECD, Swab and Surge Pressures – MPD

Initial HPHT Operating Window

MW may need to be raised!

Set Point ?

MPD system constant pressure.

Avoid pressure cycling.

50 psi < ECD whilst drilling.

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When Apply MPD on Culzean?

Actual Maximum Pore Pressure Unknown?

Risk of Static underbalance and not know it!

Complicated recognition of well flowing or not when need to bleed off to static MW in order to flow check well for trip out.

Perform initial drilling to top Pentland c. 500ft with conventional HPHT drilling

Get to know the well!

Apply MPD once maximum wellbore pore pressure is known (MDT’s) and operating window is defined.

Optimise drilling efficiency over remainder of section, within confines of narrow operating window.

Minimise risk of wellbore breathing, and minimise pressure cycling on the well?

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Weatherford RDI – Model IP1000

•Locked into diverter.

•No mods required to Diverter, BOP or Bell Nipple Arrangement.

•1500 psi static and 1000 psi rotating seal ratings.

Sealing

Element

Bearing Carrier

Adapter Body and Quicklock Clamp

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Key Service Providers

Rig – Ensco 101

LWD – BHI for upper sections and Sperry for HPHT Sections. Secondary contract to Weatherford.

Wireline Logging – Schlumberger

Cement – Schlumberger

Mud – MI Swaco

Mud Logging – BHI

QA/QC - Nexus

Mud coolers – Alfa Laval

Liner Hanger – Baker Oil Tools

Expandable – Enventure

MPD - @Balance

RDI - Weatherford