Context:
The primary source of hydrocarbons in the rocky underground is called kerogen: lumps of organic matter.
Relevance:
Facts for Prelims
About Kerogen
Definition and Composition:
- Kerogen is the portion of naturally occurring organic matter that is insoluble in organic solvents.
- Represents about 90% of the organic carbon in sediments.
Occurrence and Properties:
- Found in source rock and can expel hydrocarbons upon thermal cracking.
- Typical organic constituents include algae and woody plant material.
- Consists of both lighter and heavier hydrocarbons.
Role in Hydrocarbon Formation:
- Acts as a precursor to oil and natural gas.
- Has a high molecular weight compared to bitumen or soluble organic matter.
- Bitumen forms from kerogen during petroleum generation.
Types of Kerogens:
- Type I: Mainly algal and amorphous kerogen, highly likely to generate oil.
- Type II: Mixed terrestrial and marine source material, can generate waxy oil.
- Type III: Woody terrestrial source material, typically generates gas.
Impact on Hydrocarbon Generation:
- The type of kerogen largely determines the type of hydrocarbons produced in the rock.
- Different kerogen types contain varying amounts of hydrogen relative to carbon and oxygen.
- The hydrogen content of kerogen controls the yield of oil vs. gas from primary hydrocarbon-generating reactions.
-Source: The Hindu
