So gas storage has been sold off at high price with expectation that it will be filled again with cheap gas this Summer.

Yes that's the official line anyway but as various European politicians have made occasional reference to their own levels of storage as a serious cause for concern - it seems unlikely to me.

In fact if it was the case that, in the middle of winter, during a crisis with Russia/Ukraine which could blow up again at any time, with storage already heavily drained, that European Gas companies are choosing to run on empty thus forcing Gazprom into a crisis then the decision makers should be forcibly removed from post right now.

In any case Gazprom's own projected production for this year is about 500bcm. As production YTD seems to be running at about that level, Gazprom is clearly not forecasting an increase in production later this year. So unless Russian internal demand collapses spectacularly I just don't see where this expected "cheap gas later" is going to come from.

Also, and I may be wrong on this but, as far as I can see, most of the missing Russian imports were actually pre-contracted at the higher price - so the option of choosing not to purchase the gas should not even be there even if they wanted to - well not without Russian agreement anyway. But I admit that's a bit I'm not absolutely sure about.

whoa ! isn't gas fungible ? if a molecule of gas is old, or new, how does that old molecule know to be burned in preference to a new molecule ?

so it is possible to maintain a ledger showing gas volume x price, but how is that in any way meaningful ?

if gas in storage is depleted to a low pressure, there is an additional overhead(fuel) required to compress the gas to a higher pressure.

I would bet that a large part of the difficulty in understanding why EU gas prices are too cheap would be the temporary excess of gas in N America due to still-producing shale wells drilled in the good times, now rapidly depleting an not being replaced. Must displace a significant amount of LNG, making it available to EU for import. That's not going to last much longer, since all those rigs are laid down.