Lecture 5 Flashcards
Does a small degree API indicate heavy degradation?
Yes
What does the total acid number (TAN) mean?
TAN is the number of mg of KOH required to neutralize the acidity in 1 g of oil. A high TAN is associated with corrosion in refineries.
What happens to an oil’s viscosity as it is biodegraded?
It increases, light oil = 100cP, heavy oil = 10,000cP
Do the following increase or decrease during biodegradation: Saturates, Aromatics, Polar(NSO), Asphaltenes.
COMPOUNDS LIGHT HEAVY BITUMEN
saturates 55 25 20
aromatics 23 21 21
polar (NSO) 21 39 41
asphaltenes 2 14 21
What are the requirements for crude oil biodegradation in reservoirs?
Temperature is <80 C
water
nutrients (nitrogen and phosphorous)
electron acceptor
What is the paleopsteurization theory?
The reason that some oil from reservoirs <80 C do not show degradation is that prior to filling, the reservoir rock was heated to temperatures higher than 80 C and has not been recolonized since oil entered it.
Where in a reservoir are microorganisms more abundant?
The oil-water contact (OWC) zone
What does a demethylation of hopane indicate?
A heavily degraded oil
Why are pristane and phytane good relative markers for biodegradation?
They are very hard to degrade, so persist even as the hydrocarbons of similar size common in lighter oils are degraded away in heavy oils.
