In presently known small oil fields, a remaining recoverable reserve of about 3,100 million bbl appears evident. As much as 2,000 million bbl remain in place in abandoned small fields, of which at least 500 million eventually may be recovered through redevelopment or, in a few cases, mining. Reserves of oil in stripper wells amount to about 5,200 million bbl. Research on only 2 basins, Gulf Coast and Permian, indicates that, should a high rate of drilling activity persist into the future, at least 10,000 million bbl more in small fields could be anticipated in the United States. This suggests that a total of at least 19,000 million bbl of oil in small fields remains to be recovered in the future in the United States.
Gas from presently-known small oil fields should account for more than 17 tcf, nearly all nonassociated. In addition, at least 67 tcf of gas and nearly 2,000 million bbl of condensate will come from small, nonassociated gas fields. It is not known how much gas, as compared with oil, will be found in small fields as a result of future exploration. The amount will be substantial.
An enormous exploration effort will be required to yield this petroleum. The aggregate return is substantial, but because it is from a collection of small fields, it will not be possible to optimize exploitation in the same way as for a similar amount of petroleum from a few large fields. Neither will it be possible to achieve comparable production capacities.
In both the United States and the rest of the world, given the required drilling effort, small fields will be found far into the future. They probably will not be able to offset the eventual decline of the world’s large fields but will sustain a viable industry well into the 21st century.