Dynamic Reservoir Behaviour and Production Due to Periodic Supply of Wind Power

Wind power can replace power from gas turbines and thus reduce the CO₂ emissions related to oil production. However, a main challenge with wind power is the variability in power production due to weather variations. The water injection pumps are often major power consuming units. The water pumps were therefore identified as possible non-critical loads in an isolated power system with variable power supply. The power to a non-critical load can be varied and even stopped depending on the power supply. The objective of the present work was to study how variable water injection rates affects oil production.

Using simulated wind power curves, water injection profiles for a model oil field were constructed. Reservoir simulations show that the oil production is almost insensitive to variable injection rates if the injected volumes were the same. Lower injected rates and volumes resulted in lower oil production. This was most pronounced in the plateau phase of the production, but later the differences become gradually smaller. Thus, reducing the water injection volumes with 30 % decreased the total oil recovery by less than 5 % after 28 years.

If constant water injection rates are needed thermal power can supply wind power. This will increase the CO₂ emissions. However, if wind power not used by the water injection pumps can be utilised for other unit operations significant reductions in CO₂ emission can still be obtained.