BEIJING (AFX-ASIA) – PetroChina Tuha Oilfield Co has signed a 15-year contract to supply 520 million cubic meters of natural gas each year to Xinjiang Guanghui Natural Gas Development Co Ltd, a subsidiary of Xinjiang Guanghui Industry Co Ltd (SHA 600256), the China Business times reported, without citing sources. The newspaper said Xinjiang Guanghui Natural…