Lecture 3

Question 1

What are the three forms of petroliferous organic matter?

Answer 1

1) solids/ coal
2) liquids/ crude oil
3) gases/ natural gas

Question 2

For every 1,000 carbon atoms which goes through the carbon cycle (photosynthesis & cellular respiration/ degradation) how many on average will “leak” and sink int sediments

Answer 2

1 carbon atom. The carbon cycle is 99.9% efficient.

Question 3

Why is crude oil harder to trace than coal?

Answer 3

Because oil is mobile, thus may move from where it was produced.

Question 4

What organisms is crude oil believed to have derived from?

Answer 4

phytoplankton, zooplankton, algae, higher aquatic plants, small marine organisms like invertebrates and fish.

Question 5

What process creates kerogen from the lipids, proteins and carbohydrates in biomass? What temperature does kerogen need to form?

Answer 5

Diagenesis, 50 C

Question 6

What compounds are formed during catagenesis and at what temperatures?

Answer 6

Petroleum, and then natural gas is created at 150-200 C

Question 7

What process produces methane and graphite from natural gas, and what temperature is required for these products to form?

Answer 7

Metagenesis, 250 C

Question 8

The zone in the Earth’s crust where oil is generated via catagenesis, and then released from the source rock is called what?

Answer 8

the Oil window/ Oil Kitchen

Question 9

Do petroleum biomarkers come from the lipids that were in living creatures?

Answer 9

yes

Question 10

Name some useful biomarkers in petroleum.

Answer 10

Steranes (from eukaryotic hormones)
Hoptanes (hopanoids in bacterial membranes)
Isoprenoids (from chlorophyll)
Porphyrins (from chlorophyll)
Carotanes (from plant pigments)

Question 11

What is the likely biological origin of a sterane skeleton with 2 carbons coming out of the chain?

Answer 11

Plant/ terrestrial origin.

Question 12

How are biomarkers used in the petroleum industry?

Answer 12

Because the biomarkers are so complex and various, they can be used to trace an oil from its origin to maturity (oil-source rock correlations)

Question 13

What three types of rock are needed to form an oil/gas reservoir?

Answer 13

1) Source rock (organic rich, generated oil in geological past)
2) Reservoir Rock (porous sediments that can store liquid hydrocarbons)
3) Cap rock (non-porous rock, e.g. shale or clay. fluids separate according to density)

Question 14

True or False. The oil layer under the gas cap (oil leg) has 80% of its pore space filled with water.

Answer 14

True, the water saturated part of the reservoir is all water in its pore space.