öljyliuske

Öljyliuske, also known as oil shale, is a sedimentary rock that contains significant amounts of solid organic matter, called kerogen, from which liquid hydrocarbons can be economically extracted. This kerogen is a precursor to petroleum and natural gas. When oil shale is heated to sufficiently high temperatures (a process called retorting), the kerogen breaks down into synthetic crude oil, gas, and a spent residue.

The formation of oil shale occurs under conditions of low oxygen and high organic productivity, typically in ancient lake beds or marine environments. Over geological time, organic material accumulates and is buried, undergoing gradual transformation into kerogen. The composition of oil shale varies, but common minerals include carbonates, silicates, and clays.

Economically viable extraction of oil from oil shale has been a challenging endeavor. Historically, high extraction costs, environmental concerns associated with mining and processing, and competition from conventional petroleum sources have limited large-scale production. The energy required for retorting can also be substantial, sometimes approaching the energy content of the oil produced.

Despite these challenges, oil shale remains a potential source of hydrocarbons, particularly in regions with large deposits, such as Estonia, the United States, and China. Research and development continue to explore more efficient and environmentally sound methods for oil shale processing, including in-situ retorting techniques that aim to heat the rock underground, reducing surface disturbance. The environmental impact of oil shale extraction and processing can include significant water usage, greenhouse gas emissions, and land disturbance.