Absolute porosity is the percentage or volume of void spaces or porosity of rocks that can contain hydrocarbons. Porosity is the measure of a rock’s ability to hold hydrocarbons like oil and gas, water, and condensates. Absolute porosity contains effective (interconnected) and ineffective (isolated) porosity. Effective porosity is the volume of connected pores, but isolate is the pore volume which is not connected to the pore network. Isolated porosity can be significant in volcanic rocks and some carbonates.

1. Soran University
Faculty of Engineering
Department of Petroleum Engineering
Petroleum Geology
Title: Total (absolute) Porosity and Isolated Porosity Measurement
Lab Number: 3
Name: Raboon Redar Muhammed
Group: B (II)
Lab Date: 27/10/2019
Supervisor(s): Mr. Foad Yousefi
Ms. Meriam

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1. Aim
The main aim of this experiment is to find out the total (absolute) porosity and isolated porosity of a rock.
2. Introduction
Absolute porosity is the percentage or volume of void spaces or porosity of rocks that can contain
hydrocarbons. Porosity is the measure of a rock’s ability to hold hydrocarbons like oil and gas, water, and
condensates. Absolute porosity contains effective (interconnected) and ineffective (isolated) porosity.
Effective porosity is the volume of connected pores, but isolate is the pore volume which is not connected to
the pore network. Isolated porosity can be significant in volcanic rocks and some carbonates.
(Nielsen‐ Marsh, C.M. and Hedges, R.E.M., 1999)
3. Equipment and Materials
1. Pumice Rock
2. Water
3. Electronic Balance
4. Beaker
5. Mortar and Pestle
6. Pycnometer
7. Small Funnel
8. Wire Gauze
9. Bunsen Burner
4. Procedure
1. First, measure the mass of the rock by the electronic balance.
2. Heat the rock by the Bunsen burner.
3. Crush the rock by the rock breaker.
4. Measure the mass of the crushed rock by electronic balance.
5. Pour water into a pycnometer and measure its mass (mass of pycnometer + water)
6. Pour out the water and put the broken rock into the pycnometer.
7. Then pour the same amount of water into the pycnometer again using a graduated cylinder.
8. Measure the mass of the pycnometer which contains crushed rock and water.
9. Subtract the mass of the pycnometer which contains rock and water from the mass of pycnometer
which contained water only.
10. Find the density of the water. (ρ=m/v)
11. Convert the mass of displacement water to volume which is equal to the volume of crushed rock or
in other words, it’s equal to the volume of the grains. (use density rule ρ=m/v)
12. Find density of the rock by this rule (ρrock=Mgrain/Vgrain)
13. Find volume of the grain (Vgrain) for the rock before breaking by this rule
(Vrock= M rock before crushing /ρrock)

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14. Bulk Volume was found in the last experiment.
15. Find absolute porosity by this rule (φ=(Vb-Vg)/Vb)
16. Isolated porosity is equal to this absolute porosity minus the previous lab’s effective porosity.
5. Calculation and Results
Mass of the rock = 18.54g
Mass of the crushed rock = 18.5g
Mass of pycnometer = 28.87g
Mass of (pycnometer + water) = 128.87g
Density of water (ρ=m water/v water) = (128.87-28.87) / 100 = 1.0058g/cc
Mass of (pycnometer + water + rock) = 139.06g
Mass of displacement water = mass of (pycnometer + water + rock) – mass of (pycnometer + water) =
139.06 – 128.87 = 10.19g
Displaced water volume is equal to the volume of the crushed grains = Vg = mw/ρw = 8.76 / 1.0042 = 10.13cc
To determine the porosity of the original sample, first the grain density of the rock must be determined then
divide the rock’s mass to its density to get the rock’s volume.
Density of the grain (ρ = m/v) = 18.5 / 10.13 = 1.82g/cc
Volume of the rock = m/ρgr = 18.54 / 1.82 = 10.18cc
Bulk volume from previous lab experiment = 31.08cc
Absolute porosity = (Vb – Vgr) / Vb = (31.08 – 10.18) / 31.08 = 0.67 = 67.24%
Isolated Porosity = Total Porosity – Effective Porosity (from previous lab) = 67.24% – 19% = 48.24%
6. Discussion
Crushed grains always have smaller weight than the rock, but be careful, not to lose crushed grains while
crushing and pouring into beakers. Having a pumice rock with total porosity 67%, and a small amount of
effective porosity 19% with large amount of isolated porosity 48.24% is pretty much a close result to reality
and nature. Because pumice rocks contain holes where gas bubbles where trapped in the molten lava
creating so many isolated pores. (McPhie, J., M. Doyle, and R. Allen, 1993)
7. Conclusion
Pumic rocks usually have a total porosity range between 64-85%. (Lockwood, J.P.; Hazlett, R.W., 2010). It
can be said that the porosity of pumic rock is always big because of its lithology, but that does not mean a

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reservoir with pumic rock is a good reservoir, regardless of interconnected pores, factors such as fluid
conductivity or permeability also effect too much.
8. References
Nielsen‐ Marsh, C.M. and Hedges, R.E.M, (1999). Bone porosity and the use of mercury intrusion
porosimetry in bone diagenesis studies. Archaeometry, 41(1), pp.165-174.
McPhie, J., M. Doyle, and R. Allen, (1993). Volcanic Textures A guide to the interpretation of textures in
volcanic rocks Centre for Ore Deposit and Exploration Studies, University of Tasmania, Hobart,
Tasmania.198 pp.
Lockwood, J.P.; Hazlett, R.W. (2010). Volcanoes: Global Perspectives. Chichester: Wiley-Blackwell. pp.
184–185.