1. Skinfaks/Rimfaks IOR – Strong Horses in The Gullfaks Family
Classification: Statoil internal Status: Draft
Skinfaks/Rimfaks IOR – Strong Horses in The Gullfaks Family
Sandsli, 8.februar 2005

2. Skinfaks/Rimfaks IOR (SRI) – strong horses in the Gullfaks family
Topics to be covered:
Seismic amplitudes in exploration
Existing technology to reduce cost and increase reserves
Production technology issues
Examples of flexibility built into the concept
Lessons learned
Skinfaks/Rimfaks IOR. RES/PRO-seminar, November 2005.

3. Situation in year 2001:
The SRI team also matured the Gulltopp (Dolly) discovery to PDO level in 2003
Rimfaks Brent:
Production start year Spring 2001: IOR possibility documented, 2 infill wells + extra gas handling capacity gives 2.1 MSm3 of extra oil.
GF Sør L+M templates, prod.start Sept flowlines to GFC for GF Sør Brent gas production. Extra capacity and tie-in possibility at L/M for upsides in GF Sør Field.
Prospects defined in the Brent Gp. and Statfjord Fm. in the Ole, Dole and Doffen (ODD) segments. (Later named Skinfaks.)
Skinfaks/Rimfaks IOR. RES/PRO-seminar, November 2005.

4. Proven segments: N2 and N3 Upper Brent Prospects:
Exploration well in ’Dole’(N3) and ’Ole’ (N2) segments drilled in spring, 2002
Proven segments: N2 and N3 Upper Brent
Prospects:
N4 upper Brent. P(f): 97%
N5 upper Brent. P(f): 80%
N1 upper Brent. P(f): 90%
Prospects:
N4 lower Brent. P(f): 56%
N1 lower Brent. P(f): 46% (defined in 2004)
N1 Statfjord. P(f): 40 %
N4 Statfjord. P(f): 90%
Skinfaks/Rimfaks IOR. RES/PRO-seminar, November 2005.

5. X X Rimfaks Brent IOR Skinfaks
DG1, DG2 and DG3 are decision gates in Statoils project development model
DG1 team establ.
33/12-8S
DG1
(BoK)
DG2
(BoV)
DG3
(BoG)
PDO
del.
Rimfaks Brent IOR
Static (G&G) model used:
3D IRAP RMS (built 2001)
Dynamic (res.) model used:
3D Eclipse 300 (PDO mod.)
3D Eclipse 300 (new model, built 2002)
Elements included in production strategy:
- 2 infill wells.
- 3 MSm3/Sd ekstra gas pr.
- Gas reinjection, blowdown
from oct.2010 (PDO strategy)
3. infill well, with DIACS
3 -> 4
MSm3/Sd extra gas prod.rate
Volume reduction (significant!)
Skinfaks
Static (G&G) model used:
2D IRAP Classic GeoX
3D IRAP RMS
Dynamic (res.) model used:
Field analogue MBAL models
3D Full Field Eclipse 100 (Brent reservoir)
Elements included in production strategy:
- Water Injection X
- 5 conventional, horisontal wells.
- Depletion
DIACS compl.
Gas lift
Segm.N1 UB incl. in ’basis’
- Gas Injection X
- Wells: ML + 1 sidetr.
- N1 UB and N4 Statfj. excl. from ’basis’
Skinfaks/Rimfaks IOR. RES/PRO-seminar, November 2005.

6. DG1
(BoK)
DG2
(BoV)
DG3
(BoG)
PDO
del.
33/12-8S
DG1 team establ.
Feasibility study phase
DG1/BoK concept:
A Gullveig Statfjord well was a part of the project in the DG1 and early DG2 phases. Later excluded.
Project feasible. Establish project team. Go on with concept (screening) studies.
Skinfaks/Rimfaks IOR. RES/PRO-seminar, November 2005.

7. 4 GF-concepts evaluated: GFC
DG1 team establ.
Scr. ph. 1
Screen.phase 2
Scr. ph. 3
33/12-8S
Feasibility study phase
DG1
(BoK)
DG2
(BoV)
DG3
(BoG)
PDO
del.
4 GF-concepts evaluated:
GFC
Gulltopp
GFA
’A’
’B’
Continue with optimising concept ’D’ for a final concept selection (AP1 – Approval point 1).
’C’
’D’
L/M
Skinfaks
As we now know, concept for Gulltopp was in next screening round changed to paltform well.
Rimfaks IOR
Skinfaks/Rimfaks IOR. RES/PRO-seminar, November 2005.

8. Wells and pipelines in a network
For the SRI project: Skinfaks and Rimfaks wells prognosed with very different tubing head pressures
Impact on production profiles
Decision: Two flowlines instead of one, from the SRI prod.system.
Wells and pipelines in a network
PROJECT
Discipline
Leaders:
Drilling, Well and Production Technology
Petroleum Technology
Facility (Subsea)
Reservoir simulation
Flow assurance
”Nodal analysis”
Tools:
OLGA
GAP/PROSPER
ECLIPSE W. NETWORK OPTION
Skinfaks/Rimfaks IOR. RES/PRO-seminar, November 2005.

9. ”The SRI Technical Forum”
The SRI Core Team
”The Technical Forum”:
Project members from all engineering disciplines (Reservoir, ProTech, Drilling, Completion, Flow Assurance, Subsea, Pipeline,Topside)
A leader was appointed
Meetings were held regularly (every week)
”The SRI Technical Forum”
Which tasks do the other persons have ?
How are my data used ?
Possibilities? Limitations?
Consequences?
Concept screening/selection
Design Basis Document
Technical solutions
Skinfaks/Rimfaks IOR. RES/PRO-seminar, November 2005.

10. 9 variants of concept ’D’ evaluated:
DG1 team establ.
Scr. ph. 1
Screen.phase 2
Scr. ph. 3
Scr. Ph. 4
33/12-8S
Feasibility study phase
DG1
(BoK)
DG2
(BoV)
DG3
(BoG)
PDO
del.
9 variants of concept ’D’ evaluated:
- 1 or 2 templates, 1 or 2 flowlines, with or without smart wells.
Selection criteria:
NPV (and then IRR and NPV/CAPEX discounted)
Robustness (drilling), and flexibility wrt. upside volumes
To L/M
Recommendation, AP1, end of october 2003: Concept ’3S’ (2 templates, 8 slots, 2 flowlines, smart wells (DIACS, one ML):
BUT: Further work the following weeks weakens the project economy significantly: Cost increase (rock dumping, pilot well in segm.N4), delayed prod.start (Jan.06 => Oct.06).
As we now know, concept for Gulltopp was in next screening round changed to paltform well.
Recommendation from Project end of November.2003:
Postpone DG2/BoV. Improve concept and economics.
’Basis’ well
’Upside’ well
Skinfaks/Rimfaks IOR. RES/PRO-seminar, November 2005.

11. 11 variants of concept ’SRI to GFC via L/M’ (re)evaluated:
DG1 team establ.
Scr. ph. 1
Screen.phase 2
Scr. ph. 3
Scr. Ph. 4
Scr. Ph. 5
33/12-8S
Feasibility study phase
DG1
(BoK)
DG2
(BoV)
DG3
(BoG)
PDO
del.
11 variants of concept ’SRI to GFC via L/M’ (re)evaluated:
- 1 or 2 templates, + 1 or 2 satellites, 1 or 2 flowlines.
- Further optimising of subsea wellhead locations and subsea/pipeline cost.
- Increased volumes (3.RF well, Skinfaks N1 segment, Skinfaks gas lift)
Upside volumes quantified, value (risked) calculated.
Selection criteria: NPV (and then IRR and NPV/CAPEX disc.)
To L/M
Recommendation from Project, February 2004:
Optimise concept ’2SX’ (1 template, 1 satellite, 2 flowlines) further towards DG2.
As we now know, concept for Gulltopp was in next screening round changed to paltform well.
’Basis’ well
’Upside’ well
Skinfaks/Rimfaks IOR. RES/PRO-seminar, November 2005.

12. Discussion with partners on ’low cost’ alternatives:
DG1 team establ.
Scr. ph. 1
Screen.phase 2
Scr. ph. 3
Scr. Ph. 4
Scr. Ph. 5
Scr. Ph
33/12-8S
Feasibility study phase
DG1
(BoK)
DG2
(BoV)
DG3
(BoG)
PDO
del.
Discussion with partners on ’low cost’ alternatives:
Early in the concept selection phase (spring 2003), alternatives for SRI based on re-use of existing infrastructure (I, J, K templates) were briefly reviewed from the operator and put behind for specific reasons, but without any formal process or documentation.
Now, license partners want to compare concept 2SX with other alternatives, making use of existing infrastructure:
38 (!) combinations/variants were evaluated
Screening criterion: NPV. In addition: Relative value (NPV/CAPEX disc.), IRR, technical maturity and risk, and flexibility for realising upside volumes.
As we now know, concept for Gulltopp was in next screening round changed to paltform well.
Partners approved concept 2SX (AP1/DG2), September 2004
Skinfaks/Rimfaks IOR. RES/PRO-seminar, November 2005.

13. After AP1, your influence on the concept as subsurface engineers is very much reduced.
Statoil’s Project Development Model,
Planning Phase:
In Statoil’s governing documentation (AR05 ++) the focus on AP1 seems less than on the formal approval point DG2 (provisional project sanction).
At AP1, concept selection point: Important with a good picture of the resource potential in the area.
Formal requirements for uncertainty analysis on volumes and production profiles.
As we now know, concept for Gulltopp was in next screening round changed to paltform well.
Skinfaks/Rimfaks IOR. RES/PRO-seminar, November 2005.

14. This development benefits from flexibility in existing infrastructure
Classification: Statoil internal Status: Draft
PDO delivered Dec.2004
PDO approved Feb.2005
This development benefits from flexibility
in existing infrastructure
Majority of subsea production system is based on proven building blocks.
Full flexibility for producing wellstream through any flowline back to GFC.
Extra hubs for tie-in of future flowlines on tie-in manifold, template N and satellite N5.
Increased flowline diameter from 6” to 8” between template N and satellite N5.
Multiphase meters on each well.
Included separate meter on gas lift header.
Majority of valves are actuated and controlled from GFC.
Providing additional connection points for potential future developments at a low pre-investment cost

15. Reserves and CAPEX (cut-off year 2020)
(CCE-2 is last project update, per September 2005)
Reserves and CAPEX
PDO 2020
CCE-2 Upd 2020
Oil (MSm3)
5,71
6,21
Rich gas (GSm3)
2,58
2,57
CAPEX (MNOK05)
3432
3588
Results, CCE2 (upd. cost, plan and volumes)
Unit
Cut-off year 2020
b.tax
a.tax
NPV 7%
MNOK 05
5 572
1 349
Break even price, oil
USD/bbl
9,0
10,3
IRR % 73 33
NPV in MNOK05 has increased with a factor of 3-4 since the PDO
- 1/3 of effect due to increase in oil production volumes
- 2/3 of effect due to increased prices on oil and gas
Skinfaks/Rimfaks IOR. RES/PRO-seminar, November 2005.

16. Skinfaks/Rimfaks IOR – strong horses in the Gullfaks family
Lessons learned:
Combining infill drilling (IOR) and new disoveries can make a profitable project.
Involve the license group EARLY in the concept selection phase.
Document also ‘obvious’ choices wrt. concepts screended out.
The focus on the concept selection point (AP1) should be stronger in Statoil’s governing documentation, wrt. line and partner involvement.
Create a technical forum for continuous, cross-disciplinary discussions ‘on working level’ (not only at core team level).
Define and place the ‘system responsibility’ role early. Make sure that various models (wells - pipeline network) are consistent.
Strive to get flexibility included in the concept. It will most certainly pay off!
Skinfaks/Rimfaks IOR. RES/PRO-seminar, November 2005.