Mature Fields Hold Big Expansion Opportunity

Mature fields While big discoveries and major new developments deservedly grab the headlines, mature fields are the backbone of global oil and gas production. Revitalizing these fields extends their productive lives and offers significant opportunity to expand worldwide reserves. A 2011 report, “Mature Oil Fields—Unleashing the Potential,” by IHS Cambridge Energy Research Associates, indicated that approximately two-thirds of global daily average oil production comes from mature fields and that the percentage is increasing over time. The report considered fields mature if they had produced more than 50% of their established proved plus probable resource estimates or had produced for more than 25 years. The term mature field does not have a single definition. Many engineers consider a field mature when production has declined to less than 50% of its plateau rate. Individual companies may apply their own definitions. “We consider the subsurface and the surface,” said Olivier Heugas, a member of the mature field team at Total’s headquarters near Paris. “For the subsurface, we consider a field mature when the cumulative production has reached 50% of the initial 2P (proved plus probable) reserves. And for the surface, given the aging facilities, we consider a field mature after 10 years of production. So when one of the two criteria is reached, we consider it a mature field. “There are other criteria we might consider, such as BSW (basic sediment and water) levels or a sharp increase in gas/oil ratio or depletion rate. It is on a case-by-case basis. There have been young fields with these subsurface or surface problems, and other fields that have produced for 10 years without these problems.” A Huge Global Resource Regardless of the definition, mature fields are a huge global resource. With reserves categorized as proved or probable, attempts to expand reserve levels come at a relatively low risk. Modest additions to a base of this size can be very substantial.