I don't think its a concern, CNOOC and CPC have been working together to explore for oil since 2003, while Sinopec supplies the island with the majority of its daily gasoline. The Diplomatic recognition is just politics, and Tawain and China both currently have economic interests in Chad, there is no need to use ERHC as a pawn so that China and Tawain don't appear to be working together in the oil world when they have been openly working together for almost a decade in the search for oil, so there is no need to hide their cooperation when everyone knows they openly cooperate together.