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Approximately 5,000 years ago Chinese coastal people were
boiling sea water to produce salt. As high density human
settlement penetrated further and further inland and increasingly
relied on farming, salt — critical to human survival as a vital food
supplement and preservative — became a valuable commodity.
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 more
than 50 g/l. The water is then evaporated using a heat source,
leaving the salt behind.
About 2,000 years ago the technology began to evolve. The
inhabitants began to dig wells with percussive drilling systems
instead of digging them by hand with shovels. By the beginning of
the third century AD, wells were being drilled up to 459 ft (140 m)
deep. Rural farmers in China still use this drilling technique for
water wells today. 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 , much like a seesaw, and this lifts up the drill stem
about 3.3 ft (1 m) . The pipe is allowed to drop, and the drill bit
crashes down into the rock, pulverizing it. Inch by inch, drilling
slowly progresses.
It has been speculated that percussive drilling was derived
from the pounding of rice into rice flour. While it may seem that
this was a fairly crude technology, the methods became quite
sophisticated over time. Eventually, these ancient drillers had
developed most of the tools and techniques one might see on a
modern drilling rig, albeit on a smaller scale and without the
benefits of modern machining methods.
At regular intervals in the drilling, the crushed rock and mud
at the bottom of the hole needed to be removed. A length of
hollow bamboo with a leather foot valve would then be lowered to

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