Natural gas is found in underground reservoirs
A natural gas reservoir is a location where natural gas is trapped in the subsurface of the earth. These reservoirs are composed of porous and permeable rocks that can hold significant amounts of natural gas confined by impermeable rock or water barriers.
What are proved reserves?
Proved reserves is the volume of natural gas that analyses of geological and engineering data demonstrate to be recoverable under existing economic and operating conditions. Proved reserves could increase each year wnen new, successful exploratory wells are drilled and as more information is obtained about fields where current wells are producing natural gas. New technologies and increases in natural gas prices can change previously uneconomic natural gas resources into proved reserves. Because they depend on economic factors, proved reserves shrink or grow with changes in wholesale (spot) natural gas prices and production costs. The U.S. Energy Information Administration (EIA) bases its estimates of proved reserves on analysis of data collected annually from domestic oil and natural gas well operators.
How large are U.S. proved natural gas reserves?
U.S. natural gas proved reserves have increased nearly every year since 2000. Major advances in natural gas exploration and production technologies, such as horizontal drilling and hydraulic fracturing in shale, sandstone, carbonate, and other tight geologic formations, contributed to increases in natural gas production and reserves.
According to U.S. Crude Oil and Natural Gas Proved Reserves, Year-end 2021, as of December 30, 2021, U.S. total natural gas proved reserves—estimated as wet gas (which includes hydrocarbon gas liquids [HGLs])—totaled about 625.4 trillion cubic feet (Tcf). This volume was a 32% increase from the estimated 473 Tcf of proved reserves at end of 2020. The dry natural gas portion of these reserves (after removal of HGLs) is about 589 Tcf, a 32% increase from the 445 Tcf of dry gas reserves in 2020.
What are technically recoverable resources?
A common measure of the long-term viability of U.S. domestic natural gas and crude oil as energy sources are the remaining technically recoverable resources (TRR), which consist of proved reserves and unproved resources.1 Estimates of TRR are highly uncertain, particularly in emerging plays where relatively few wells have been drilled. Early estimates tend to vary and shift significantly over time because:
- New geological information is gained through additional drilling.
- Long-term productivity is clarified for existing wells.
- New well productivity increases with technology improvements and better management practices.
EIA publishes TRR estimates in the Assumptions to Annual Energy Outlook Oil and Gas Supply Module based on the latest available well production data and information from other federal and state governmental agencies, industries, and academia. EIA estimates in the Annual Energy Outlook 2023 that as of January 1, 2021, the United States had about 2,973 trillion cubic feet (Tcf) of TRR of dry natural gas.
1 Unproved resources include resources that have been confirmed by exploratory drilling. They include undiscovered resources that are located outside oil and natural gas fields where exploratory drilling has confirmed the presence of resources. Unproved resources also include resources from undiscovered pools within confirmed fields when they occur as unrelated accumulations controlled by distinctly separate structural features or stratigraphic conditions.
Last updated: June 2, 2023, with most recent data available.