Publication Name: The Cooper & Eromanga Basins Australia
Authors: E. Allen and D.V. Boger
Date Published: June 1989
Number of Pages: 22
Reference Type: Book Section
Abstract:
Gas displacement techniques are now widely used for enhanced oil recovery (EOR), especially for tight reservoirs,and include carbon dioxide flooding, nitrogen flooding, hydrocarbon flooding, fire flooding and steam flooding.
These methods can result in miscible or immiscible displacement, depending on the reservoir conditions and
the gas composition. Miscible displacement has been the preferred method to date due to the very high theoretical recoveries obtained in slim-tube displacement tests. However, these tests do not account for viscous fingering which can have a severe effect on the actual recovery figures, especially for the highly unstable gas displacement methods.
Experimental results for miscible displacement in a large radial Hele-Shaw cell at a range of viscosity ratios are
compared with preliminary data for immiscible displacement. Both the experimental data and an analysis of the major forces indicate that immiscible displacement gives a significantly greater sweep efficiency to that obtained for miscible displacement at the same mobility ratio. The fingering behaviour can be characterised by using fractal analysis which may be used for comparison ofEOR methods and for scale-up of the results in reservoir simulation.