Ever consider that exporting countries building reserves may not be doing it to quickly work the market, but rather are storing above ground supplies in preparation for quick mobilization for their own use?

War would be an obvious reason to have those oil supplies at the ready.  Since WWI and WWII proved that rapid ramp up in industrial ability and the ability to mobilize quickly, even if the target of a first strike, is critical to getting on a winning footing, then I could easily see the Russians or other nations wanting to have an oil supply which can be used rapidly and not be dependent on geology at hand.

Not everything is about market warfare, and I think there are a lot of players getting more nervous about energy than what is let on.

In mutually offensive wars, a cubic kilometer of oil in one place is among the first targets of missile or air attacks.  Which is why I said it makes peacetime sense.