The main Soviet oil producing region was in the Caucasus Mountain district. On a previous thread on this topic I posted a reference which quoted Hitler as saying that capturing the Caucasus oil fields was a top priority, and if the Germans didn't capture them then they would lose the war.Would they have needed to push on beyond Western Russia and the oil regions? A major problem that the Soviets would have to overcome would have been resources for building modern weapons. Oorah! charges against German forces with plenty of oil might not have been that effective.
It would be interesting to war game it with any putative German advance stopping at a line roughly going from Oskolkova down through Perm to the mouth of the Volga, or even as far as the Urals. What resources did the Soviets have east of that line to draw upon? Oil, coal, hydroelectricity - yes, but what of other essential elements? Did they have the horses and manpower to substitute for the US trucks and keep factories and farming running?
The Germans captured some of the outlying oil fields in the North Caucasus, but the Soviets had so thoroughly destroyed them before retreating that the Germans got no oil from them before they were recaptured by the Soviets.
The Germans didn't reach the main oil fields around Baku (on the western shore of the Caspian Sea, about half way down), but that was their primary objective in their advance through the southern Soviet Union.
Prior to WWII the two leading oil producing regions of the world were the US and the Soviet Union, the latter mainly in the Caspian Sea region. The US produced something like half the world's oil at the time, which was one of the reasons why they were so flush with cash.
The other oil producing regions of the world were much smaller, and these included Venezuela, Mexico, Persia (Iran), Iraq, Burma, the Dutch East Indies (Indonesia), and Romania. The main oil discoveries in the Middle East, along with those of North Africa, Canada, and elsewhere came after the war.
BP was founded as a state owned oil company to exploit the oil fields of Persia. The UK got a fair bit of oil from Venezuela as well, along with smaller amounts from Iraq, Burma, and elsewhere.
Romania, and several other minor producing areas in the Balkans could only supply part of Germany's oil needs, which is why they were so short of oil. They had stockpiled oil before the war, but not enough to take them very far. They could buy some oil from the Soviets before the two were at war, but the Soviets wouldn't sell them enough to maintain their existing stockpiles, let alone build up a war reserve. Once the war started the clock was ticking, and the Germans either had to capture the oil fields of the Soviet Union or else knock the British out of the war in order to import oil from overseas. Without that German tanks would grind to a halt, German aircraft would be grounded, and German U-boats would stay in port.
One of the main objectives of the Japanese smash and grab exercise in south-east Asia was the oil fields of the Dutch East Indies. Without that oil the Japanese fleet wasn't going anywhere.
One of the things which might have been a real game changer in the war is if the oil reserves of Libya had been discovered in the 1920s instead of after the war, and had been exploited as a major supply by the Italians. That would have made the Mediterranean a major theatre of war for the Germans as they sought to secure their oil supplies, and the Italians might have been able to use their oil revenues to build a bigger navy to defend their oil producing regions.
The two together might have been able to expel Britain from the Mediterranean. Of course the British plans in the region would have been different as well as they sought to either capture the oil fields or destroy them.
I don't know if there were some technological limitations which would have prevented the Libyan oil from being discovered and exploited before it was, but this is one of the few "what ifs" that I've seen suggested that might really have changed the course of the war.