U.S. crude oil and lease condensate proved reserves increased by 12% in 2018 compared with 2017, and natural gas proved reserves rose 9% year/year, setting new records, according to data from the Energy Information Administration (EIA).

In addition, crude oil and lease condensate production increased by 17% year/year and total gas production was up 12% in 2018, both also records.

The numbers, based on data reported on survey forms EIA-23L, were published in the agency's annual reserves report, which was issued Thursday.

Proved reserves of natural gas reached 504.5 Tcf at year-end 2018, compared with 464.3 Tcf at the end of 2017, EIA said. Shale formations accounted for 68% of gas proved reserves in 2018, up from 66% in 2017. The annual average Henry Hub spot price was $3.35/MMBtu in 2018, a 12% increase compared with $2.99/MMBtu in 2017.

The largest net increase of gas proved reserves of all states was reported in Texas, where producers added 22.9 Tcf in 2018 as a result of increased prices and development of the Wolfcamp/Bone Spring formation in the Permian Basin. The next largest net gains were found in Pennsylvania (14.2 Tcf) within the Marcellus Shale and in the Permian portion of New Mexico (4.2 Tcf) also from the Wolfcamp/Bone Spring.

On the crude oil side of the ledger, U.S. proved reserves were 43.8 billion bbl at year-end 2018, compared with 39.2 billion bbl at year-end 2017, EIA said. Texas was the state with the largest net increase, adding 2.3 billion bbl of crudeand lease condensate proved reserves, thanks to increased prices and development in the Permian in West Texas.

"The annual average spot price for a barrel of West Texas Intermediate crude oil at Cushing, OK, increased 29% in 2018, from $51.03 in 2017 to $65.66," EIA said.

The next largest net gains in crude oil and lease condensate proved reserves in 2018 were in New Mexico (750 million bbl) and North Dakota (422 million bbl).

EIA defines proved reserves as estimated volumes of hydrocarbon resources that analysis of geologic and engineering data demonstrates with reasonable certainty are recoverable under existing economic and operating conditions.

"Reserves estimates change from year to year as new discoveries are made, as existing fields are thoroughly appraised, as existing reserves are produced, as prices and costs change, and as technologies evolve," the agency said.

Potential natural gas reserves in the United States were an estimated 3,374 Tcf at the end of 2018, a record high, the Potential Gas Committee (PGC) said earlier this year. It was the highest resource evaluation in PGC's 54-year history, and larger than the group's 2016 assessment by about 20%, due to reassessments of shale gas resources in the Northeast and Midcontinent areas and conventional and tight gas in the Midcontinent and Rocky Mountain areas.