Editing Petroleum (section)

==== Kerogen formation ====
Some [[Phenols|phenolic compounds]] produced from previous reactions worked as [[bactericide]]s and the [[Actinomycetales]] order of bacteria  also produced antibiotic compounds (e.g., [[streptomycin]]). Thus the action of anaerobic bacteria ceased at about 10&nbsp;m below the water or sediment. The mixture at this depth contained fulvic acids, unreacted and partially reacted fats and waxes, slightly modified [[lignin]], resins and other hydrocarbons.<ref name="Schobert-2013" /> As more layers of organic matter settled into the sea or lake bed, intense heat and pressure built up in the lower regions.<ref name="Braun-1993">{{Cite report |url=http://www.osti.gov/servlets/purl/10169154-cT5xip/ |title=Chemical reaction model for oil and gas generation from type 1 and type 2 kerogen |last1=Braun |first1=R.L. |last2=Burnham |first2=A.K. |date=June 1993 |publisher=Lawrence Livermore National Laboratory |doi=10.2172/10169154 |access-date=March 18, 2018 |archive-url=https://web.archive.org/web/20200517104249/https://www.osti.gov/biblio/10169154-cT5xip/ |archive-date=May 17, 2020 |url-status=live}}</ref> As a consequence, compounds of this mixture began to combine in poorly understood ways to [[kerogen]]. Combination happened in a similar fashion as [[phenol]] and [[formaldehyde]] molecules react to [[urea-formaldehyde]] resins, but kerogen formation occurred in a more complex manner due to a bigger variety of reactants. The total process of kerogen formation from the beginning of anaerobic decay is called '''diagenesis''', a word that means a transformation of materials by dissolution and recombination of their constituents.<ref name="Schobert-2013" />