Increased oil recovery from Halfdan chalk by flooding with CO2-enriched water: a laboratory experiment

Injection of CO² is a method that may increase the recovery of oil from Danish chalk reservoirs in the North Sea. The method is used elsewhere, particularly in North America, but has so far not been used in the North Sea and has nowhere been used for chalk reservoirs, and the performance of the method when used for North Sea chalk is therefore uncertain. A laboratory flooding experiment was conducted at the Geological Survey of Denmark and Greenland on a sample from the Nana-1X well of the Halfdan oil field in the Danish North Sea in order to test the efficiency of CO₂-enriched water to produce additional oil from chalk. The sample is a low-permeability chalk from the Ekofisk Formation and represents rocks that are marginal to the Halfdan reservoir in an economical sense.