In 2015, the seven biggest publicly traded Western energy companies, including Exxon Mobil Corp. and Royal Dutch Shell PLC, replaced just 75% of the oil and natural gas they pumped, on average, according to a Wall Street Journal analysis of company data. It was the biggest combined drop in inventory that companies have reported in at least a decade.

In 2014, U.S. crude oil and lease condensate proved reserves increased to 39.9 billion barrels—an increase of 3.4 billion barrels (9.3%) from 2013. U.S. proved reserves of crude oil and lease condensate have risen for six consecutive years, and exceeded 39 billion barrels for the first time since 1972. Proved reserves of U.S. total natural gas increased 34.8 trillion cubic feet (Tcf) to 388.8 Tcf in 2014. This increase (9.8%) boosts the national total of proved natural gas reserves to a record-high level for the second consecutive year.

Taking advantage of lower oil prices, India will next month begin filling up its maiden strategic oil reserves to insulate itself from supply disruptions.