The Russians are losing refineries, not oil fields.
The Russian crude trade to countries like India pushes the price down globally, but limits Russian access to refined fuels and products.
It also limits their ability to fund the war.
https://www.reuters.com/business/energy/russia-extends-diese...
Petroleum products are refined and consumed near the point of use because they're not very shelf stable. Petrol is not shipped internationally in any significant quantity, neither is diesel for these reasons.
Take down any production capacity anywhere and you'll have shortages locally but crude oil supplies will divert to other refining capacity and fall in price.
Conversely take down crude oil supply...
Diesel is shelf stable for 6-12 months, which is long enough to ship anywhere in the world.
Attacks on refineries also have impact on worlds petrol/diesel prices - one of biggest exporters turned into an importer at a time when there is world shortage of refining capacity and cracks spread is at or near all time high.
> It also limits their ability to fund the war.
It does but it also makes petrol and diesel more expensive around the world.