Kerogen maturation

Park et al. (1990) suggested an alternative mechanism that may induce free convection in the subsurface the methanogenesis-driven convection system. By numerically simulating reaction-transport equations. Park et al. (1990) calculated that the generation of methane from kerogen maturation can induce kilometre scale flow in a porous medium because of the density dependence of groundwater on methane concentration. 

Barth T., Borgund A.E., Hopland A.L., Graue A. (1988) Volatile organic acids produced during kerogen maturation—amounts, composition and role in migration of oil. Org. Geochem. 13, 461—5. 

Ujllfi Y. (1986) Contact-metamorphic effect on parameters for kerogen maturation. Org. Geochem. 9, 375-378. 

Primary migration presents a different problem Shales are impermeable and normally provide excellent seals that inhibit upward petroleum movement (see later). How then can petroleum emigrate from an impermeable source bed into a permeable carrier formation It is not enough to invoke simple compaction of clay during burial. When clays compact, most of the porosity is lost in the first kilometer or so of burial. Temperatures are still too low to permit kerogen maturation. At the depths at which petroleum generally forms (some 3 to 4 km) little porosity loss takes place. 

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