Oil Wells produce 0.25 Oil per turn each, accumulating to 3 Oil per day. Oil Wells are cheap to build and operate, and never run out of Oil to drill for. Each city can have up to 10 Oil Wells.
There are no National Projects that increase Oil production. To increase Oil Production, a nation must increase the number of Oil Wells it has.
Oil is used to fuel Oil Power Plants which are a staple Power Improvement for new nations. Oil is the sole resource used in producing Gasoline. Gasoline is a very valuable manufactured resource. Nations in other Continents that wish to produce Gasoline must import either Oil, increasing its value as an export.