1. How to increase the oil recovery in GFS Statfjord ?
Forslag til Gullfakslandsbyen

2. Gullfaks Sør Statfjord Formation
PDO 1995: Large volumes in the Statfjord fm.
Main reservoir in the Gullfaks Sat.
7 wells 2000 Sm3/d.
1999: F-4 T3H and G-2 T3H in production.
Produced much less than expected.
Statfjord Fm. on hold.
2001: G-3 T2H in production.
Behave in accordance to new expectations.
Unexpected gas breakthrough.
2002/2003: IOR project initiated.
Identified problems:
Limited reservoir communication
Gas limitation

3. Development of GFS Statfjord reserves
F-4 and G-2 drilled
DIACS and MLT
G-3 drilled

4. GFS Statfjord Challenge:
Complex reservoir with low recovery, goal +18% (LTP )
PDO – 12.6 MSm3. Today 5.1 MSm3
Wells drilled
Additional perforation of G-2 H and F-4 H in lower Statfjord (summer 2003)
G –1 H with DIACS (2003), periodically shut in.
G –2 YH MLT with DIACS (2004)
F –2 YH MLT with DIACS (2004)
G-3 Y3H, 3 branch MLT with DIACS (2005), SHUT in
GI MLT with DIACS (2006), only one branch injecting

5. How can we increase the recovery ?
Could look into:
Well solutions
Technological solutions
Drilling has so far been challenging. Simple or complex wells ?
Wells spacing ?
Increase of gas injection, number of GI ?
Uncertainties in reserve estimates
When start blowdown ?
Economic considerations
Economic development
No economic limitations, KPI: recovery

6. Reflections could be made around
What should be used as a KPI ?
Recovery vs. NPV
Who makes the decisions?
Petroleum law, partners influence
Prioritarisation of gas injection or gas export ?
(high gas price: more economic to sell gas than inject in marginal oil reservoir)
Subsea
rig availability a challenge
rig costs increasing
Simulation model provided, already implemented at NTNU, 2006_students