Yulin City, Shaanxi Province, known as the China version of Kuwait, has Shenfu coalfield, one of the eighth largest coalfields in the world. Every square kilometer of land has underground wealth 1 100 million yuan, and the potential value of mineral resources exceeds 46 trillion yuan, accounting for 1/3 of the whole country. There are 6 tons of coal, 140 cubic meters of natural gas, 40 tons of salt and 1 15 kilograms of oil under every square meter of land.