By John Richardson
A lot of the projects which have pushed the world into severe overcapacity were based on the assumption that China would remain in big deficits for many basic commodity chemicals and polymers.
It was thought that the world's most-important market would remain a sink for surpluses for a very long time at a time when tough questions over financing were rarely asked.
But it's become clear over the past few years that many of the assumed deficits won't be there.
China is seeking very high levels of self-sufficiency through building a big wave of new refineries integrated downstream with crackers, polymers and other derivatives.
Now the search for what to build - and what to provide storage and other support services for - outside China to supply China is likely to be a great deal more rigorous and selective.
The usual approach to this problem would be to conduct a study looking at the announced projects while also examining where China lacks the economics and the technology in a particular product.
"I am afraid this won't work in the political context of this country," a Westerner based in Shanghai told me last week.
"If a chemical looks like being in big deficit and even if China has no obvious competitive advantages or technology to start production, this doesn't mean it won't be built.
"The government would rather haemorrhage money than be dependent on imports for anything they regard as strategic."
Those able to read the minds of China's senior leadership should therefore be able to do very good business.
Another approach might be one of bitter regret if you haven't already got substantial capacity on the ground in China.
More constructively, if you have missed the boat what would be better is to take China's demand largely out of the equation when deciding your strategy for basic chemicals.