What is the cost with accepting global deliveries?

I have an oil power plant. To keep it running, I am accepting global deliveries.

The expense of running is $856/hour The burning rate is 8.93k barrels/day (k? what does k mean?).

What is with this $4500 figure? Is it how much it costs to fill my plant or something?

I can "recent transactions" in the budget.

So still with some simple math it does not computer.

8.93 barrels /day 
divided by capacity 2000 
= 223 days till i run dry.

The recent transaction shows 3 deliveries in just a few months.