U.S. proved crude reserves declined by nearly 5 billion barrels last year due to low commodity prices.
The U.S. Energy Information Administration (EIA) said between the end of 2014 and end of 2015, U.S. crude oil and lease condensate proved reserves decreased from 39.9 billion barrels to 35.2 billion barrels.
That decline marked a decrease of 4.7 billion barrels, or just under 12 percent.
Over the same period, the agency said that proved reserves of U.S. total natural gas decreased by 64.5 trillion cubic feet (Tcf) from 388.8 Tcf in 2014 to 324.3 Tcf.
During that period, the average West Texas Intermediate (WTI) crude oil spot prices declined almost 50 percent and the average spot price of natural gas at the Louisiana Henry Hub declined more than 40 percent.
“The significant reduction in prices, which resulted in a more challenging characterization of existing economic and operating conditions that are considered in the definition of proved reserves, led to downward revisions across a broad range of U.S. producers,” the EIA said.
Despite falling prices, U.S. production of crude oil and lease condensate increased by 7 percent year-over-year in 2015.
That growth marked the seventh straight year that U.S. crude and lease condensate production has increased.
The EIA said that Texas and North Dakota saw the largest extensions of crude oil and lease condensate in 2015.
However, because of downward revisions, both states saw a net reduction in proved reserves.
Texas had the largest proved reserves of any state in 2015 but the state also saw the largest proved reserves decline of any state last year.
Texas posted a net decrease of 1 billion barrels of crude oil and lease condensate proved reserves from 2014 to 2015, the EIA said.
New Mexico saw the largest net increase in proved reserves of crude oil and lease condensate of all states in 2015.
Those gains were mostly tied to the development of the Wolfcamp shale and Bone Spring plays in southeastern New Mexico’s portion of the Delaware Basin.
On the natural gas front, Ohio added more than 5 Tcf of proved natural gas reserves, with most of those gains coming from the Utica Basin.
The gains propelled New Mexico ahead of Arkansas and the Gulf of Mexico and made New Mexico the state with the ninth-largest natural gas reserves.
The EIA found that proved natural gas reserves in Pennsylvania and Oklahoma experienced “large” net downward revisions.
However, those declines were partially offset by developments in the Marcellus and Woodford shale plays.
The EIA said that those offsets reduced the decline in Pennsylvania to just 3.9 and just 3.6 Tcf in Oklahoma last year.
Total U.S. natural gas production climbed 4 percent year-over-year, marking the tenth consecutive year of production growth.
For both oil and natural gas, the EIA found that net downward revisions to reserves “exceeded both the total discoveries and the estimated production for 2015.”