The genesis of hydrocarbons.

Book excerpt: Abstrakt Modern petroleum geology is built on the theory of the organic origin of hydrocarbons. It is claimed that they are formed as a result of dipping of organic carbon-rich sedimentary layers and their thermal transformation by which hydrocarbons are generated. Conventional looking at the formation of hydrocarbons is based on buried in a sedimentation pool dead biomass of organisms and their long-lasting microbial degradation in an anaerobic environment with the simultaneous influence of temperature and pressure. This process creates a transformed organic material of high molecular weight called kerogen. About 1% of the live mass of the organic may be stored in kerogen in favorable conditions. Regardless of the type of kerogen, increasing temperature and pressure leads to the dissociation temperature or the cracking and forms a crude oil or natural gas. The secondary cracking at a higher temperature and pressure may result in the smallest particles of hydrocarbons, methane (Sephton, Hazen 2013). This theory does not answer the question of why there are massive accumulations of hydrocarbons reaching hundreds of millions of tons when their hitherto regarded as the mother layers, source rocks, is so little spread in the geological profile?