Production from carbonate reservoirs

There are several different methods for obtaining porosities, and investigations show that core analysis measurements under surface conditions give higher values than for restored-state conditions. Complexity in the make-up of reservoir rocks creates problems in oil production; the extent of barriers may be uncertain when few wells have been drilled. Imbibition is of particular importance when there is water advance in fractured reservoirs. The level of reservoir pressure is important in oil recovery. Fluid injection is undertaken to maintain or build up pressure, but the injected fluid, when of a suitable nature, also performs other functions. Waterflooding, hydrocarbon and carbon dioxide miscible drives, and thermal and polymer techniques for enhanced oil recovery are described. 23 references.