Weekly data from the U.S. Department of Energy also showed weekly U.S. crude production hit a record high last week of nearly 10.4 million barrels per day (bpd).
For 2019, the EIA forecast a crude production increase of 570,000 bpd to 11.27 million bpd.
Oil prices fell in post-settlement trade after data from the American Petroleum Institute showed USA crude inventories rose by 5.7 million barrels last week, a bigger-than-expected rise.
The fall in investment, coupled with drop in oil prices, also demolished benchmark crude futures from $100 in 2014 to $30 in 2016.
USA oil prices were under pressure from expectations that weekly crude inventory data from the US government, due on Wednesday, would show a second straight rise.
Brent crude futures fell 47 cents to $63.87 per barrel by 1500 GMT.
Brent futures slipped 32 cents to $64.47 a barrel by 1232 GMT, while US crude futures fell 33 cents to $62.27, although both contracts had eased off their lows in line with a recovery in S&P futures.
A voice for Wall Street in the White House, Cohn's resignation came after he lost a fight over Trump's plans for hefty steel and aluminium import tariffs.
The April crude oil futures started the session at 62.30, and was down 22 cents. Trump's protectionist theme adds a new wave of concerns, with increasing signs of a trade war leading to turbulence in some risk assets. When asked whether the Organization of Petroleum Exporting Countries was anxious about further USA crude output growth, OPEC Secretary General Mohammad Barkindo said he wasn't and pointed to robust demand.
Refineries processed 15.9 million barrels of crude per day last week, producing 9.9 million barrels of gasoline daily.
WTI traders should watch the price action at $61.20. That compares with a 2.5-million-barrel build in the previous week. The administration is considering clamping down on Chinese investments in the US and imposing tariffs on a broad range of imports to punish Beijing for its alleged theft of intellectual property, according to people familiar with the matter.
Although the International Energy Agency on Monday reported that surging output form the us will dominate the global oil industry for the next five years, several experts think the market is also changing to the point where shareholders are now seeking shale companies that have enough self discipline to not pump to the point where another glut occurs.