How Refinery work?

Hi,

Even though I play for more than one year, I could not figure out how Refinery work...
Sometimes them produce more when placed near Tib field, other times when placed near Power Plant.
I supposed it depends on the harvester/power plant level, however, near a power plant with 2-3 levels lower than the harvester, it's producing more than near the harvester...

I am trying to find the best solution to optimize cash + energy production, but this is beyond my logic :tired_face:

Does anybody know which is the logic behind?

Thanks!