CPG Petroleum Geology & Reservoir Characterization

Question 1

What is the primary source rock for petroleum?

Accepted Answer

Shale

Answer

Shale is widely recognized as the primary source rock for petroleum because it contains a high concentration of organic matter, primarily kerogen. Under specific conditions of heat and pressure over geological time, this organic matter matures and transforms into hydrocarbons (oil and natural gas), which can then migrate to reservoir rocks.

Question 2

What is porosity in a reservoir rock?

Accepted Answer

The space available to hold fluids

Answer

Porosity in a reservoir rock refers to the percentage of the total rock volume that is made up of void spaces or pores. These interconnected pores are crucial because they are where hydrocarbons (oil and gas) and water are stored within the rock formation. High porosity is essential for a rock to be an effective reservoir, determining its storage capacity.

Question 3

Which tool is commonly used to evaluate reservoir properties?

Accepted Answer

Well log

Answer

Well logs are continuous records of various physical properties of the rock formations encountered in a borehole, measured by instruments lowered into the well. They provide critical data on porosity, permeability, lithology, and fluid content, which are essential for evaluating reservoir quality and identifying hydrocarbon-bearing zones, guiding drilling and production decisions.

Question 4

What is the function of a cap rock in a petroleum trap?

Accepted Answer

To seal the reservoir

Answer

A cap rock, also known as a seal rock, is an impermeable layer of rock that overlies a permeable reservoir rock. Its crucial function is to prevent the upward migration and escape of hydrocarbons from the reservoir, trapping them in place and forming a petroleum accumulation. Common cap rocks include shale, salt, and anhydrite, which create an effective seal.

Question 5

Which factor influences reservoir permeability?

Accepted Answer

Pore throat size

Answer

Permeability is a measure of a rock's ability to allow fluids to flow through it. While porosity indicates the amount of space, pore throat size (the size of the connections between pores) dictates how easily fluids can move. Larger, well-connected pore throats result in higher permeability, which is vital for efficient hydrocarbon production from a reservoir.

(CPG) Certified Petroleum Geologist Practice Test

(CPG) Certified Petroleum Geologist Practice Test

CPG Petroleum Geology & Reservoir Characterization