Zigong Deep-Well Salt Drilling and Brine Extraction Technique

The Zigong well-salt drilling and extraction technique stands as one of ancient China’s greatest engineering achievements and is widely regarded as the precursor of modern oil drilling. Originating in Sichuan Province, its core is a percussive method known as cable-tool drilling: artisans used a foot-treadle lever to lift and drop a heavy bit, repeatedly pounding through rock layers to reach underground brine.

A major leap came in the 11th century during the Northern Song Dynasty with the Zhuotong Well, a small-diameter deep-well design that predated Western counterparts by over 800 years. In 1835, the Shenhai Well in Zigong reached 1,001.42 meters—the world's first well to exceed one kilometer—marking the full maturity of China's cable-tool drilling technology.

The complete salt-making process includes drilling, brine extraction, sun-drying, and boiling. Artisans must master techniques such as well surveying, deviation correction, and tool fishing—skills passed down orally from master to apprentice. Zigong is known as the Salt Capital of China and was officially established as a city because of its salt industry in 1939. This millennia-old craft, preserved in its entirety, stands as a living fossil of global drilling technology.