The proposed research will investigate gas injection into the Lower Cretaceous reservoirs with the aim of quantifying the potential of enhanced oil recovery for these reservoirs through various gas injection options.
The Lower Cretaceous Reservoirs in the Valdemar field are low permeable chalk reservoirs which are generally under-exploited.
These reservoirs, developed by solution gas drive, have shown a large variation in productivity. Although the production mechanism is not completely clear, it is for certain that a further increase in recovery needs additional production energy and reduction in the residual oil saturation.
Due to the low permeability in these reservoirs, gas injection is preferred to water injection in order to supplement energy to the reservoir because of the lower viscosity and higher injectivity of gas. Besides, injected gas can achieve different extents of miscibility with reservoir oil and reduce the residual oil saturation. In the case of complete miscibility, injected gas can recover 100% of the oil on the microscopic scale.
In general, gas injection is considered a highly effective EOR technology with numerous successful examples.
It has a sound theoretical basis allowing reasonable production forecast, more significant increase in recovery than many other EOR methods, versatility in the choice of the injection gas, suitability to low permeable formation and flexible implantation methods (flooding, huff and puff, water-alternating-gas etc.). It is considered as the only viable technical EOR technique for DUC reservoirs according to the DUC EOR Screening Study in 2013.
The project is funded by the Danish Hydrocarbon Research and Technology Centre.