Prosjektforslag 10 Eksperter i Team - Gullfakslandsbyen 2007 GF: Syklisk gassinjeksjon i Statfjord FM MÅL: Øke oljeproduksjonen fra Gullfaks med 10%. NTNU, 17. januar 2007

Gullfaks field – Segment I1. 8. This shows you an overview of the installations. Close neighbours are the Statfjord field, Snorre/Tordis/Vigdis and the Visund field. Gullfaks came on production in 1986 and has produced 311 million Sm3 of oil to date. 9. In addition to the main Gullfaks field, there is also a major satellite development that came onstream in 1998. This developement was actually planned with smart wells only, but so far only a few have been installed. 10. Looking at this map of the Gullfaks reservoir, we find the projection of the C-platform here. Before C-43, there had been one smart well at Gullfaks - C-29 - completed as a smart well in 1998. The well is still producing, but the downhole valves have not been moved since 2001. 11. Now let us focus on the I1 SEGMENT which is a separate structure at the Statfjord level an OWC which is about 100 m shallower than the main area to the northeast. The STOOIP in Statfjord in the I1 segment is 12 million Sm3. 12. The map of the I1-segment is what we call a flooding map and shows our current estimate of water, oil and gas saturation fronts. We fin C-43 here. C-16 came on-stream in 1993 and has produced 3,3 million Sm3 of oil to date. A41 injected water from 1994, but was replaced with B-40A in 2001. PCSI15 is a possible future drilling target. 13. In the next slide I will show you a cross-section along this red line.

Introduction Gullfaks Statfjord Fm. - Segment I1 Completed in April 2004 Production experience with a zone DIACS C-16 Prod/gas inj. B-40A Waterinjection 14. The wellpath of C-43T2 is shown in black. Overall the C-43 well came in very close to the geological prognosis. The fault is shown in red here, was encountered in Lunde_A and confirms a fault with a dip of approx. 90. The average dip of faults in the Gullfaks area is >300 indicating that the origin of this fault is related to a different tectonic event, perhaps a collapse feature post-rifting. The C-43 was TD was set in Lunde C1 at 6467 m MD/ 2040 m TVD MSL. 15. B-40A injecting water into S1/S2 and S3 - the lower part of the reservoir. 16. C-16 has produced since 1993, and over the last two years we have also injected gas into the well to capture addict oil. 17. So now – lets focus on the smart completion in C-43T2 with a two zone DIACS.

Production Experiences Measured Reservoir Pressures C-43T2: Completion Prod. Upper Lower Upper C-40A: Injecting 3000 Sm3/d C16: Prod. SI Gas Inj. Prod. 34. So lets go to the seven months of production history that we have with operating and producing C43T2. This is the pressures downhole gauges in C16 in green and C-43 in red. C-43 was put on production in late April, and we tested firt both zones individually at 1000 Sm3/d. Then we let both valves fully open at a total rate of 1800 Sm3/d – 1500 from the upper zone and 300 from the lower. In July, we reduced the upper zone to draw more on the lower zone. In October we tested a 10% watercut, and we closed the lower zone producing only from the upper. I will come back to the last testing we did. 35. A40B: SI - Injecting 3000 Sm3/d 36. C-16: SI - Producing - Injecting gas - SI - producing

Production Experiences Model Reservoir Pressures 01.12.2004 - layer 8 C-16 B-40A C-43T2 37. This show the reservoir pressures in Lower Statjord from our Eclipse simulator. We are bulding presure in the B-40A area, in order to get the presssure support in C-43. Pressure - bar

Production Experiences Model Reservoir Pressures 01.12.2004 C-16 B-40A C-43T2 38.

Production Experiences Model Oil Saturations 03.2004 – layer 6 B-40A 12.2004: C-43T2 C-43T2 40. Model oil saturations 03.2004 -- 12.2004

Oppgave nr 10: Syklisk gassinjeksjon i C-16 Bruke eksisterende Eclipse-modell. Historietilpasse to års med produksjon fra C-16. Kjøre prediksjoner for å bestemme fremtidig produksjonsprofil for forskjellige måter å oprerere brønnen. Basert på egne simuleringer og virkelige kostnader, beregne nåverdi for syklisk gassinjeksjon.