What do you do if you’re sitting on reserves of $2 trillion and you’re afraid that a sinking U.S. dollar will erode the value of that pile of cash?

If you’re China, you buy things. Small things, naturally. $40 billion for oil drilling rights in tracts off Nigeria’s coast, for example. Another $40 billion in loans to Venezuela, Russia, and Brazil in exchange for future oil deliveries.

And you don’t really care too much if you overpay. Or at least if you overpay by the standards of international oil companies that are worried about making a positive return on their investment. If the value of the dollars in that national portfolio are worth less everyday, then you might even be willing to take a negative return on your oil investment just to get billions out of a bigger negative return position in the U.S. dollar.

Especially if, as history argues, the price of oil will go up as the value of the U.S. dollar sinks. (Oil is traded, so far at least, in U.S.dollars.) 

And if you believe, as many investors inside and outside China do, that the world’s supply of U.S. dollars is set to keep on growing, leading to further declines in its value, and the globe’s supply of easily discovered and produced oil will keep on shrinking, leading to further increases in its value.

This willingness to spend depreciating dollars today for appreciating oil tomorrow, though, is making it harder for publicly-owned, supposed-to-make-a-profit oil companies to gain the right to explore in the world’s most promising oil frontiers.

Look at what’s happening to Exxon-Mobil, (XOM) in Ghana, for example.

 Exxon Mobil has struck what it thought was a binding deal to acquire Kosmos Energy for $4 billion. Kosmos has a stake in the Jubilee field, the largest deepwater field in Africa.

Ghana’s national oil company is negotiating with China’s CNOOC (CEO) over a counter-bid for Kosmos. You’d think that Kosmos would have the right to sell to ExxonMobil or to any other company that it chooses, but no, the government of Ghana is threatening to block the sale, arguing that it wants to protect the country’s national interest.

What’s Ghana’s national interest in this? The international oil companies are arguing that it’s in the country’s interest not to block the sale and damage Ghana’s reputation as a transparent and fair market. I’m sure the Chinese are arguing that it’s in Ghana’s national interest to get the most for its oil.

It’s likely that cash will trump appeals to fairness. (And I’m not even considering the effect of any cash that might flow under the table to officials in Ghana’s government.)

And if Ghana does go for the cash, I expect China to turn in the highest bid. ExxonMobil wants the oil, for sure, but it’s not going to up its bid beyond the point where a profit turns into a loss. CNOOC, on the other hand, isn’t using the same accounting standards.

Paying so much that the project makes a loss is good business if one of your goals to to dump a few more billion in depreciating U.S. dollars.