A study of 36 oil-producing fields on the Norwegian continental shelf also shows that the majority of these fields had a significant growth in their reserves.
In fact, on the Norwegian continental shelf, more than 10 fields with reserves in excess of 200 million barrels of oil equivalents (o.e.) have doubled their reserves compared to when a decision was taken to develop these fields. Several fields, including Ekofisk, Troll and Valhall, have tripled the original reserves.
Nevertheless, Dr. Verma observes that the U.K. North Sea have the lowest reserve growth, this being an exception because the high cost of development dictated more precise reserve estimation upfront and hence lowered reserve growth.
In his article, Dr. Verma mentions five factors that effect reserve growth: increased in place hydrocarbon volumes, the discovery of new pools, improved recovery factors, enhanced oil recovery, and economics.
The Norwegian Petrolem Directorate, in their 2007 RESOURCE REPORT, says that the reserves in a field increase when decisions on new projects for development or enhanced recovery are made. New reservoir characterization may also lead to increases or decreases in estimates of the reserves.
To work on existing fields is all the more important as the U.S. National Petroleum Council (GEO ExPro, Vol. 4, NO. 4, 2007) says that our global energy future largely depends on continued development of known resources and application of enhanced oil recovery. There is a job to do for the good geoscientists.
