“Unlocking the Secrets of Ancient China’s Ingenious Gas Drilling: A Hidden History of Energy Innovation”
From the very start of brine extraction in Sichuan, drillers began encountering pockets of natural gas – composed mainly of methane – trapped beneath the salt. The Jialingjiang formation which feeds Sichuan Province’s abundant brine aquifers was formed by the evaporation of a large inland sea during the mid-Triassic Period, around 225 million years ago. This salt layer forms an impermeable dome which traps large quantities of natural gas, produced by the decomposition of ancient marine zooplankton and algae. At first, this gas was seen as a useless byproduct or even an unwelcome hazard; indeed, the gas was often contaminated with hydrogen sulfide, a highly-toxic gas with could induce nausea, unconsciousness, and even death depending on its concentration. Eventually, however, the gas’s flammable properties were recognized and it began to be used for household lighting, heating, and cooking throughout the region. But it was not until the Second Century C.E. that large-scale gas extraction truly began in earnest, largely in response to a resource depletion crisis. Previously, salt had been produced by boiling brine over wood fires. But as the industry grew and local forests became severely depleted, drillers turned to the abundant supply of natural gas as an alternative source of fuel.
Exploiting Sichuan’s natural gas reserves required the development of yet more advanced technology, including the “Kang Pen” drum. Invented in the late 18th Century, this device sat atop the wellhead and allowed both natural gas and brine to be extracted and separated simultaneously. Chinese drillers also invented one of the world’s first carburetors to combine natural gas with air, producing an efficient-burning mixture for heating the brine evaporation pans. They even developed a rudimentary understanding of the area’s geology, siting brine wells at the bottom of valleys and gas wells at the top of hills where gas pockets accumulate under salt domes.
