Improved Oil Recovery in Heterogeneous Reservoirs

More than 50% of the oil is left behind after oil production is completed in most of the oil reservoirs on the Norwegian continental shelf. This is not acceptable in a global energy perspective. The single most important reason for such a low oil recovery is reservoir heterogeneities, i.e. variations in reservoir rock properties. A resent study by the Norwegian Petroleum Directorate indicates that a realistic potential for improved oil recovery is on average ca. 7% for the Norwegian Continental Shelf and amounts to a value in the order of US$100 billion. However, to obtain this goal intensified research emphasizing heterogeneous reservoirs is required. Reservoir heterogeneities severely affect the flow of gas, oil and water in the reservoir and thus, is o f great concern for the choice of production strategies, reservoir management and the ultimate oil recovery. This project emphasizes the impacts from reservoir heterogeneities on oil recovery, utilizing interactions between laboratory experiments at com plementory scales and numerical simulations. A worldwide unique nuclear tracer imaging technique obtains in-situ fluid saturation information in larger scale heterogeneous laboratory models, 0.1-4.0 sqm blocks of rock, with gravity, capillary- and viscous forces simultaneously acting. Local impacts from various types of heterogeneities are determined using high spatial resolution imaging at 100microns in MRI experiments with animated 3D visulization capabilities. Reservoir simulators are then used to scal e up the results to be valid for field simulations. Emphasis will be on heterogeneities like fractures, variations of permeability, capillarity and wettability. The objective is to be able to describe, understand, predict and model fluid flow in heterogen eous reservoirs to improve the ultimate oil recovery. The project is an international collaboration between universities and the oil industry in the US, UK, France and Norway.