sentences:  The main problem has been pipeline capacity.As a result of delays in US government approval of the Keystone XL system and other pipelines, only of Canadian crude reached the Gulf Coast in 2012.Since Canadian heavy oil and bitumen was much lower in price than heavy oil from other countries, oil companies started buying up and reversing idle pipelines which used to carry imported oil from the Gulf Coast to the Midwest to carry Canadian oil in the other direction.