Porosity Measurement | What is porosity and how is it measured?
Assignment Porosity Measurement
You are one of your company’s petrophysicists and are asked by your multi-disciplinary team colleagues to explain to them the difference between the total porosity of a formation and its effective porosity, highlighting the critical importance of the effective porosity for hydrocarbon production from a reservoir formation.
Solution
The total porosity of a formation is defined as all of the pore space present within a rock sample, whether it exists as an isolated pore sealed by secondary cementation, or is connected to other pores.
The effective porosity of a formation is defined as the pore volume of only the interconnected pores. Only the effective porosity contributes to hydrocarbon production, but a number of downhole well logs indirectly sense the total porosity. While reservoirs always have both total and the effective porosity, differences between the two can sometimes be critical for reservoir performance.
Assessment Porosity Measurement
1. Which types of porosity can be found in carbonate reservoirs? (Select all that apply.)
A .Intraparticle Correct ✔
B .Interparticle Correct ✔
C .Fenestral Correct ✔
D .Fracture Correct ✔
E .Moldic Correct ✔
2. In the summation-of-fluids technique, what is measured in the pore spaces of fresh core of known bulk volume? (Select all that apply.)
A .Gas Correct ✔
B .Water Correct ✔
C .Oil Correct ✔
D .Pyrite
3. Which types of porosity can be found in sandstone reservoirs? (Select all that apply.)
A .Dissolution Correct ✔
B .Vugular
C .Intergranular Correct ✔
D .Fracture Correct ✔
E .Microporosity Correct ✔
4. With increased overburden in chalk formations, what reservoir parameters tend to decrease significantly? (Select all that apply.)
A .Hydrocarbon productivity Correct ✔
B .Gamma ray radiation
C .Permeability Correct ✔
D .Porosity Correct ✔
E .Grain density
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