petroleum geology notes

Petroleum geology

Theories of origin of petroleum:-

organic origin theory is widely accepted, as 97% of petroleum reservoirs are found in sedimentary rocks. Rest 3% are found in metamorphic as well as igneous rocks, that too with some conditions.

Inorganic theories:-

1) cosmic theory:- Bertheiot(1865) ,mendaleef(1877) suggested the formation of petroleum in earths interior by action of water on metallic carbides such as those of Ca and Fe.Another proposed mechanism involved in the interaction of alkali metals with co2 and water.

Metallic carbide + H2O vapour = CH4 + metallic hydroxide

Alkali metals + Co2 + H2O vapour = CH4 + alkali hydroxide

2) mantle theory/Gold’s earthquake out gassing theory:-

Enriched Delta(13C) of methane from hotspots of red sea, lake kivu(east africa) and pacific rise depicts an abiogenice origin(Mac donald).

Delta(13C) content in crude oil is -30%o(i.e per millenium)

some other key learning:-

oldest rock is found in greenland which is 4.2 billion years old.

2nd oldest rock is found in chota nagpur(singhbhum)

Origin of most petroleum in the world dates back to mesozoic to paleozoic

The origin of petroleum found in india lies in the cenozoic age.

NELP:- new exploration licensing policy [ it is now about 15 years old  ]

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