This war would end with Russia (or its vassals) being in control of those resources. Majority of the fuel deposits are in the western separatist regions and within Crimea's EEZ. Smaller deposits are to the east near Moldova - where there are also separatist movements that's very likely funded from Moscow as well.
Winning this war achieves multiple objectives for Russia (gaining resources, keeping NATO away from the border, dropping a future rival down several pegs, etc) that this war simply has to happen.
I have already made a clear analysis about this in one of my posts in the forum here:
https://bitcointalk.org/index.php?topic=5390494.msg59577912#msg59577912Russia just wants to remain the number one position of supplier of natural resources in the EU. They do not want any competitors in this sector because this is the most profitable and major source of income for Russia. Also, the more EU depends only on Russia for natural resources the more influence Russia will have over them which has already been proven recently. Ukraine was also causing problems for Russia with gas transit so Russia had no choice but to neutralize Ukraine to secure its finance source of income.