Chinese national oil companies have reported huge oil and gas discoveries year after year, but little has been commercialised.

Led by China National Petroleum Corporation (CNPC), the companies are never short of reserves figures that impress government officials but make little sense to technocrats.

CNPC consistently reports multiple discoveries, each with a minimum reserves size of 1 billion tonnes (7.35 billion barrels) of what it calls “geological” oil reserves.

The other two state players, Sinopec and China National Offshore Oil Corporation (CNOOC), make similar claims.