As JPMorgan's Michael Cembalest notes,

Oil and gas deposits often lie close to sectarian fault lines in the Middle East (Kurdistan and Basra in Iraq; Shi'ite areas in Eastern Saudi Arabia; Kuwait), which is why oil markets are sensitive to sectarian violence.

 In Iraq, oil deposits in the South near Basra are well-defended, and account for 75% of Iraqi production volumes. Exports from the North near Kirkuk are low after pipeline attacks earlier this year.