This cite has them at 873B of net exports with about 200B in petroleum imports in 2017:
https://atlas.media.mit.edu/en/profile/country/chn/
The net exports decreased to about 500B for 2018. I can't seem to find a dollar figure for 2018 oil but I've seen articles saying imports are up 10% by volume. So total petroleum imports are less than half of their net export amount. Meaning that they could triple their petroleum imports and still be a net exporter.