The first recorded salt well in China was dug in Sichuan Province, around 2,250 years ago. This was the first time water well technology was applied successfully to the exploitation of salt, and marked the beginning of Sichuan’s salt drilling industry. From that point on, wells in Sichuan have penetrated the earth to tap into brine aquifers, essentially ground water with a salinity of over 50g/l. The water is then evaporated using a heat source, leaving the salt behind.
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At some point around 2,000 years ago the leap from hand and shovel dug wells to percussively drilled ones was made. By the beginning of the 3rd century AD, wells were being drilled up to 140m deep. The drilling technique used can still be seen in China today, when rural farmers drill water wells. The drill bit is made of iron, the pipe bamboo. The rig is constructed from bamboo; one or more men stands on a wooden plank lever, much like a seesaw, and this lifts up the drill stem a metre or so. The pipe is allowed to drop, and the drill bit crashes down into the rock, pulverizing it. Inch by inch, month by month, the drilling slowly progresses.
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A major breakthrough was achieved around 1050 AD, allowing deeper wells, when solid bamboo pipe was replaced by thin, light, flexible bamboo “cable”. This dramatically lowered the weight that needed to be lifted from the surface, a weight that increased with the depth being drilled. By the 1700s Sichuan wells were typically in the range of 300 – 400m deep
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One bamboo pipe line would take away the brine, and others the gas. The 2,000 year plus Sichuan salt industry has drilled approximately 130,000 brine and gas wells, and 10% of those were in the immediate Zigong area. Zigong has a cumulative gas production over this period of over 30 billion cubic metres. The area continues to be a major salt producer, and many of the historical wells are still in production.

As recently as the 1950s there was still over 95km of bamboo pipeline in operation in the Zigong area.