As global oil prices fluctuate, the ‘dream’ of discovering oil reserves within South Korea resurfaces. Despite the presence of dinosaur fossils, the scientific community explains that the Korean peninsula is structurally unfavorable for oil formation.

The Origin of Oil: Not Dinosaurs, But the Sea

The long-held belief that oil originates from dinosaur remains is outdated. Current scientific consensus points to marine organic matter, such as plankton, as the primary source. Over millions of years, organic material accumulating on the seabed, buried under thick layers of sediment, transforms into liquid hydrocarbons – crude oil – under intense heat and pressure. This process requires tens of millions, even hundreds of millions, of years.

Temperature is also critical. As depth increases, so does temperature. For organic matter to convert into oil, it must reach a temperature range of 50-150°C at an appropriate depth. Outside this ‘oil window,’ gas may be produced, or the transformation may not occur at all.

The Three Essential Rock Types

Even with oil formation, a viable oil field isn’t guaranteed. Specific geological structures are necessary. Oil generated in organic-rich sedimentary rocks (source rocks) migrates through surrounding rock fractures. It accumulates in porous rock layers like sandstone or limestone (reservoir rocks). A cap rock, an impermeable layer, must then seal the reservoir, preventing the oil from escaping to the surface.

A source rock, reservoir rock, and cap rock – all three must be present within a suitable geological structure for an economically viable oil field to form. The absence of even one component can result in oil not accumulating or escaping to the surface.

Why the Middle East Succeeds, While Korea Doesn’t

Major oil-producing regions like the Middle East, the North Sea, and Texas have historically been covered by shallow seas for extended periods during the Paleozoic and Mesozoic eras. The Middle East, for example, was largely covered by the Paratethys Sea, a shallow inland sea, allowing for the thick accumulation of organic matter from plankton and marine algae. This organic matter subsequently transformed into oil as the region transitioned into land.

South Korea’s geological history differs significantly. The peninsula is predominantly composed of Precambrian metamorphic rocks, formed 500 million to 4 billion years ago, accounting for 42.7% of the landmass. Granite, formed from solidified magma, constitutes a substantial 28.2%. The terrain largely consists of igneous and metamorphic rocks, leaving little space for organic matter accumulation or oil pooling.

South Korea’s period as a seabed was relatively short, hindering the accumulation of sufficient organic material. According to the Korea Institute of Geology and Mineral Resources, the Korean Peninsula and East Asia have largely remained landmasses since the early Paleozoic era, making the formation of large sedimentary basins suitable for oil accumulation difficult.

While small sedimentary layers exist in parts of the East Sea, West Sea, and South Sea continental shelf, the 2024 exploration in the Yeongil Bay area of the East Sea did not reveal economically viable reserves. The scientific community generally agrees that, barring significant geological changes, the likelihood of discovering large oil fields in South Korea remains low.

Frequently Asked Questions

• Is there absolutely no oil in South Korea? While large-scale, economically viable oil fields are unlikely, the possibility of smaller deposits cannot be entirely ruled out.
• What is the ‘oil window’? It’s the temperature range (50-150°C) at which organic matter transforms into oil.
• What are the three key rock types needed for oil formation? Source rock, reservoir rock, and cap rock.

By Jeong Seong-hwan