Understanding Oil Prices

I apologize if this is covered elsewhere, but I haven’t’ seen it.

What is the effect of oil prices? I ran a tech savy nation with bio-fuel subs and the oil price went down. According to the home screen, this will effect GDP but I can’t tell if in a good way or bad way? Part of me says lower oil means business can start up with cheaper energy, but the other part says cheaper oil means less money on exports of oil.

So which do I want? a high demand or high supply of oil?