Here's a little general info. Colonial Pipeline runs from Houston through the south and then up to New York City area. Plantation Pipeline runs from Baton Rouge to the Washington DC area. With power out in the hurricane region, the pumping stations are unable to boost the flow and pressure on the pipelines. Most of the these pipelines are fed by other shorter lines from the refineries in the area.
The refineries that produce gas and diesel, except for the Exxon refinery in the Baton Rouge area, are idle. The main problem being people and power. Most of the refineries produce their own power but people have been unable to reach the area to check for damage and test equipment. Also with the hurricane on the way, tank farms will rearrange the volumes in the tanks, reduce or gain, so that the tanks can best withstand the winds.
One help is that the EPA has agreed to relax the clean air standards for sulfur content in gas and diesel until Sept. 15. Currently around the US there are at least 16 different formulas for gasoline depending upon where it is sold. Most of the standards are due to the states imposing their own requirements.
With the above information, one could say that the some of the price increases are due to supply and demand while others could be due to gouging.
Hope this explains some of what is going on out there.
Good luck and be safe.
Jim