I think the fires in Canada caused some of the excessive sell off, see COP they have operation in Canada too. Steep sell off also.
From the WSJ:
Exxon Mobil Corp.’s Imperial Oil and ConocoPhillips also shut some production earlier Thursday. Exxon cut output by an undisclosed amount at its 194,000 barrel-a-day mine, citing “uncertainties.” Conoco halted a 50,000 barrel-a-day mine and evacuated all staff due to a fire near the town of Anzac. They followed a move Wednesday by Nexen Energy ULC, a subsidiary of China’s Cnooc Ltd. On Wednesday, the Canadian unit of Royal Dutch Shell PLC shut down two oil-sands mines, which produce 255,000 barrels a day, that it owns in partnership with Chevron Corp. and Marathon Oil Corp.