[Notes] Petroleum Geology Part 8

 Summary of Kerogen Type

Type I            Algal Kerogen (Alginite)

Type II           Formed from lipid components (Exinite)

Type III         Woody Kerogen (Vitrinite)

Type IV         Eroded or reworked OM (Inertinite)

Type I

- waxy & cuticular material

- derived largely from algal material enriched in lipids due to microbial alteration

- hydrogen-rich

- small volume of preserved OM

- Oil will be generated

Type II

- less waxy or cuticle material

- bacteria, phytoplankton, zooplankton & minor amounts of terrigenous OM like spores and pollens

- hydrogen-rich

- more abundant than Type I

- Oil and gas will be generated

Type III

- few, if any, ester groups or aliphatic chains

- terrestrial higher plants & their parts, ie. wood, cellulose, lignin, vitrinite & huminite

- hydrogen-poor

- along continental margin

- Gas will be generated (coal)

Type IV

-  highly-oxidized inertinitic

- either oxidation of OM during deposition or degradation due to diagenetic transformation

- OM from Type III

- only gas during the later stage of maturity