How are hydrocarbons extracted from underground? | Explained Premium

Learn about the geological processes, extraction methods, and environmental impact of hydrocarbon extraction in this comprehensive guide.

Over millennia, mighty geological processes in the earth’s crust heated and compressed together pieces of life-forms that had been dead for a while. Eventually, this mulch of organic matter accumulated as hydrocarbons inside rock formations. The two Industrial Revolutions were the result mainly of people finding a way to extract these hydrocarbons and using them to drive many and great engines, whose foul breath polluted the air and water and eventually gave us global warming.

The most common forms in which these hydrocarbons exist in subterranean rock formations are natural gas, coal, crude oil, and petroleum. They are usually found in reservoirs underground created when a more resistant rock type overlays a less resistant one, in effect creating a lid that causes hydrocarbons to accumulate below it. Such formations are important because otherwise, the hydrocarbons would float to the surface and dissipate.

Experts use the tools, methods, and techniques of the field of petroleum geology to assess these rocks, including to check for their porosity and permeability. If a rock formation is highly porous, it could hold a larger quantity of hydrocarbons. Similarly, the more permeable a rock is, more easily the hydrocarbons will flow through it.

The primary source of hydrocarbons in this rocky underground is called kerogen: lumps of organic matter. Kerogen can be deposited from three possible sources: as the remains of a lake (lacustrine), of a larger marine ecosystem, or of a terrestrial ecosystem. Rocks surrounding the kerogen can become warmer, more compactified over time, exerting forces on the kerogen that cause it to break down. Lacustrine kerogen yields waxy oils; marine kerogen, oil and gas; and terrestrial kerogen, light oils, gas, and coal.

The rock containing the kerogen is called the source rock, and petroleum geologists are tasked with looking for it, understanding its geophysical and thermal characteristics, and characterising its ability to yield hydrocarbons. They also undertake modelling activities informed by observational data and dig smaller exploration wells to estimate the amount of hydrocarbons there, and report it to the relevant regulatory body.

Once a particular location is determined to be a profitable source of hydrocarbons, drilling can begin.

Drilling and reservoir engineers are responsible for extracting as much of the hydrocarbons as is gainful without damaging the reservoir, to which end they deploy a variety of methods.