Petroleum and Natural Gas
It is probably a conservative estimate to say that the Chinese were burning natural gas for fuel and light by the fourth century BC. The deep boreholes drilled for brine also yielded natural gas from time to time. These methane gas deposits tended to occur under the brine, but many boreholes, including those intended for brine, yielded only natural gas and were known to the Chinese as "fire wells". These boreholes were being drilled systematically for brine by at least the first century BC, so that deep supplies of natural gas were tapped from that date by boreholes going down over 100 metres. And the systematic search for natural gas itself by deep drilling is recorded in the second century AD.
Chang Quin 347 recorded in his book Records of the Country South of Mount Hua:
"At the place where the river from Bupu joins the Huojing River, there are fire wells; at night the glow is reflected all over the sky. The inhabitants wanted to have fire, and used to ignite the gas outlets with brands from household hearths; after a short time there would be a noise like the rumbling of thunder and the flames would shoot out so brilliantly as to light up the country for several dozen li around. Moreover they use bamboo tubes to 'contain the light', conserving it so that it can be made to travel from one place to another, as much as a day's journey away from the well without its being extinguished. Whenit has burnt no ash is left, and it blazes brilliantly." .
Bamboo pipelines did indeed carry both brine and natural gas for many kilometres, sometimes passing under roads and sometimes going overhead on trestles.
The ignition and use of the natural gas for light and fuel posed problems which were successfully overcome by the ancient Chinese. Old texts describe in some detail the complicated arrangements which were eventually adopted to control the burning of natural gas. …