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Executive summary
The Norwegian Continental Shelf (NCS) is facing new challenges in reserve replacement and improved recovery in order to maintain
the overall oil production rate from the area. A new target for an increase in oil reserves of 800 million Sm3 of oil (5 billion
barrels) by year 2015 has been set by NPD. This is an ambitious goal considering several of the large fields are on a steep
decline, and most of the recent discoveries are relatively small. A significant part of these increased reserves will have
to come from fields currently on production, from reservoir areas that have been partly or fully swept, and it is therefore
evident that Enhanced Oil Recovery (EOR) methods have to play a key role in achieving this target.
EOR methods can be divided into gas based EOR methods and water based EOR methods. Thermal methods are not considered applicable on the NCS due to the relatively light oils present, and the depth of the reservoirs.
Gas Based EOR Water Based EOR
CO2 injection Surfactants
Air injection Polymer
Nitrogen injection Alkaline
Flue gas injection Polymer gels
WAG MEOR
FAWAG
The former OG21 strategy document gave high priority to Water Alternating Gas (WAG) methods and CO2 injection for enhanced recovery. A lot of R&D and evaluation projects on CO2 injection were launched and are on-going, most of these are being CO2 WAG studies. The main challenge now in order to realize CO2 injection on the NCS is on CO2 availability and transport. It is also believed that increasing gas prices will limit the availability of hydrocarbon gas for injection purposes in the future.
There is, however, a clear need for developing alternative cost efficient EOR methods that can improve the sweep efficiency significantly. Since a majority of the fields on the NCS are being produced under water flooding (or WAG), methods that can improve the water flooding efficiency by chemical additives are of special interest and could probably be implemented with existing facilities and within the relevant timeframe.
The R&D effort in the 1980’s and early 1990’s on chemical methods gained a lot of knowledge and expertise at the research institutes and in the oil companies. The new effort should be based on the existing knowledge, focus on pilot testing and field implementation, and redoing of work should be avoided.
A lot of excellent work has been carried out on EOR for the NCS. The following main common challenges for all of the studied EOR methods have been identified and can be grouped in 3 main categories:
1. Recovery process understanding
2. Field recovery predictions
3. Pilots and field trials
The recommendations from the enhanced recovery group (TTA3) are the following:
· There is a clear need for increased support for focussed projects over a wide range of EOR methods in order to achieve the high ambitions for reserve replacement and recovery factors that have been set for the NCS fields. The EOR share of the total PETROMAKS programme should be raised significantly above today’s 7.5% of the PETROMAKS budge. Furthermore, high priority should be given to pilots on EOR methods and field trials and to launch EOR projects within Demo2000. There is today none EOR projects financed through Demo2000.
· A special initiative is recommended to generate and support projects for improved water flooding by the use of chemical additives (chemical flooding). A workshop seminar should be arranged to discuss specific R&D projects in the area of water based EOR methods (chemical additives).
· Projects on sweep improvements for gas or WAG injection i.e. Foam Assisted WAG (FAWAG), especially related to field implementation should be encourage
TTA 3 – Enhanced recovery
Tore Blaker, Statoilhydro (Lead Party rep)
tobla@statoilhydro.com
Jan Åge Stensen, Statoilhydro
jste@statoilhydro.com
Arvid Østhus, ConocoPhillips
Arvid.Oesthus@conocophillips.com
Steve Coutts, Shell
Steve.Coutts@shell.com
Sigmund Stokka, Iris
Sigmund.Stokka@rf.no
John D. Friedemann, Vetco
john.friedemann@vetco.com
Ole Torsæter, NTNU
oletor@ipt.ntnu.no
Arne Skauge, UiB, CIPR
arne.skauge@cipr.uib.no
Morten Dethloff, Halliburton
Morten.Dethloff@Halliburton.com
Anna-Inger Eide, NPD
Anna-Inger.Eide@npd.no
Ying Guo, Total
ying.guo@ep.total.no
Torleif Holt, Sintef
torleif.holt@iku.sintef.no
