# Petroleum Production Operations Questions and Answers – Formation Damage – Mathematical Expressions

This set of Petroleum Production Operations Multiple Choice Questions & Answers (MCQs) focuses on “Formation Damage – Mathematical Expressions”.

1. In a two-region reservoir model, how is the skin factor “s” calculated?
a) [(k/ks)-1]ln(rs/rw)
b) [(k/ks)+1]ln(rs/rw)
c) [(ks/k)-1]ln(rs/rw)
d) [(ks/k)+1]ln(rs/rw)

Explanation: In a two-region reservoir model, the skin factor “s” is calculated by using the formula [(k/ks)-1]ln(rs/rw). It is a dimensionless factor which gives information about the reduction of permeability.

2. What could be the reason for the pressure drop?

a) Packer dislocation
b) Oil production
c) Skin
d) Fracture

Explanation: The reason for the drop could be due to the skin or formation damage for the reduction of the original permeability. This reduction of pressure due to the skin can be calculated by using the equation ΔPs=141.2qμBs/kh.

3. The minimum (possible most negative) skin factor is obtained when the apparent wellbore radius equals to drainage radius.
a) True
b) False

Explanation: The statement is true. The minimum skin factor is obtained when the apparent wellbore radius equals to drainage radius. This is the possible most negative skin factor. This is the dimensionless unit.

4. What is the formula for calculating the pressure drop as shown in the diagram below?

a) ΔPs=141.2qμBs/kh
b) ΔPs=161.2kh/qμBs
c) ΔPs=141.2kh/qμBs
d) ΔPs=161.2qμBs/kh

Explanation: The formula for calculating the pressure drop as shown on the diagram is ΔPs=141.2qμBs/kh. Where q is the flow rate, μ is the viscosity, B is the Oil formation volume factor, k is the permeability, s is the skin h is the height.

5. Flow efficiency is less than 1 in a stimulated well.
a) True
b) False

Explanation: The statement is false. The corrected statement is Flow efficiency is greater than 1 in a stimulated well. For a damaged well the flow efficiency is less than 1 where the skin is greater than 1.
Note: Join free Sanfoundry classes at Telegram or Youtube

Sanfoundry Global Education & Learning Series – Petroleum Production Operations.

To practice all areas of Petroleum Production Operations, here is complete set of 1000+ Multiple Choice Questions and Answers.