Energy stocks were in the red Wednesday afternoon, with the NYSE Energy Sector Index falling 1.5% and the Energy Select Sector SPDR Fund (XLE) dropping 2.7%.

The Philadelphia Oil Service Sector index shed 1.8%, and the Dow Jones US Utilities index was down 1.2%.

US crude oil stocks, including those in the Strategic Petroleum Reserve, rose by 3.6 million barrels in the week ended Feb. 28 following a decrease of 2.3 million barrels in the previous week. Excluding inventories in the SPR, commercial crude oil stocks rose by 3.6 million barrels after a 2.3 million barrel decrease in the previous week, a larger gain than the 800,000 barrel increase expected in a survey compiled by Bloomberg.

Front-month West Texas Intermediate crude oil was falling 3.1% to $66.16 a barrel while the global benchmark Brent crude contract was dropping 2.6% to $69.21 a barrel. Henry Hub natural gas futures rose 2.3% to $4.45 per 1 million BTU.

In corporate news, BP's (BP) strategic review of its Castrol unit has received attention from Saudi Aramco, which is weighing a potential offer for the lubricant assets, Bloomberg reported. BP shares were up 0.9%.

Phillips 66 (PSX) said Wednesday it's ready to engage constructively and find a "path forward" with activist fund Elliott Investment Management, even though the fund "showed no genuine interest in engagement." Phillips 66 shares were falling 3.6%.

Ecopetrol (EC) shares rose 1.5% after it reported lower Q4 net income and revenue that still topped analysts' expectations.