THE ENIGMA OF OIL AND GAS-FIELD GROWTH

Growth in estimates of recovery in discovered fields is an important s ource of annual additions to United States proved reserves. This paper examines historical field growth and presents estimates of future add itions to proved reserves from fields discovered before 1992. Field-le vel data permitted the sample to be partitioned on the basis of recent field growth patterns into outlier and common field sets, and analyze d separately. The outlier field set accounted for less than 15% of res ources, yet grew proportionately six times as much as the common field s. Because the outlier field set contained large old heavy-oil fields and old low-permeability gas fields, its future growth is expected to be particularly sensitive to prices. A lower bound of a range of estim ates of future growth was calculated by applying monotone growth funct ions computed from the common field set to all fields. Higher growth e stimates were obtained by extrapolating growth of the common field set and assuming the outlier fields would maintain the same share of tota l growth that occurred from 1978 through 1991. By 2020, the two estima tes for additions to reserves from pre-1992 fields are 23 and 32 billi on bbl of oil in oil fields and 142 and 195 tcf of gas in gas fields.