After that, reserves begin to decline, as depletion begins winning the race against technological improvement. Most types of lower 48 reserves are expected to grow for at least part of the projection period. Offshore reserves grow the fastest, from 34 tcf in 1996 to 49 tcf in 2020, peaking at 50 tcf in 2017. Conventional onshore reserves grow the second fastest, and unconventional onshore reserve growth is third. Associated-dissolved onshore gas reserves, which depend on oil supply activity, are expected to decline over the forecast as oil drilling declines in the short term and becomes less productive as the years go on.
Gas production is limited by the available resources.
In NEMS we model economically recoverable resources, which are a subset of the technically recoverable resources. Technically recoverable resources, in turn, are less than the in-place resources. Resources include not only proved reserves, but inferred reserves from known fields, and undiscovered resources from new fields. Estimated resources come primarily from the assessments done by the U.S. Geological Survey for onshore regions and by the Minerals Management Service for the offshore. As technology improves, economically recoverable resources grow.