The article doesn't go into details about why they are having such trouble, just noting a lack of infrastructure and development near the wells, but I think it is important to remember that China has an image problem in many parts of the Muslim world. While that image is better than the US has, it should be remembered that AQIM recently declared war on China for the rioting in Xinjiang, and has even attacked Chinese workers in North Africa.
China is starting to have its own "colonialism" problem, which I am certain puzzles the Chinese leadership to no end. They are used to being the anti-colonialists; to now be called colonialists themselves must be odd. But it's a fact in many parts of the world, including now Iraq.