Reservoir

1. DUHOK POLYTECHNIC NIVERSITY
ZAKHO TECHNICAL COLLEGE
PETROLEUM GEOLOGY DEPT.
FOURTH YEAR – SECOND SEMESTER
Practical Petroleum Reservoir
LAP #2
Title of Experiment : porosity
Prepared By: HOGR KHALMALA
Lecturer : Mr. Alaa
Assistants : Mrs. Hiba , Mrs. Nada and Mr. Nechirvan
Submitting Day : 6/4/2024
www.isotop.co.il

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Table of Contents
1. Introduction …………………………..…….…………………………….……………… 2
2. Type of methods and methoention of procedure of any method ………..…………….… 3
A-Saturation methods ……………………………………………………… 3
 Saturation methods procedure …………………………………….… 3
B-Gravimetric methods …………………………………………………… 4
 Gravimetric methods procedure …………………………………..... 4
CGas expansion methods ………………………………………………… 5
 Gas expansion methods procedure ………………………………….. 5
3. Advantages and disadvantages ………………………………………………………...…6
4. Calculation …………………….…………………………….……………………...…… 8
5. Result and Discussion …………………….……………………………..…...………… 11
6. Conclusion …………………….…………………………….…………………….…… 11
7. Reference …………………….…………………………….……………………..….… 12

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Introduction
For many industrial applications, porosity is one of the parameters that affects how solids
interact physically and chemically with gases and liquids. Catalysts, building supplies,
ceramics, pharmaceuticals, pigments, sorbents, membranes, electrodes, sensors, active parts
of batteries and fuel cells, as well as strata and rocks that contain oil and gas are a few
examples of industrially significant porous materials. According to Klobes et al. (2006), the
volume fraction of porosity (&) is the proportion of void space (V,) in relation to the sample's
apparent total bulk volume (Vy) using Equation 1. The difference between the solid's volume
(calculated from its crystal lattice density) and the apparent total bulk volume (VT) of a
single phase material can be used to determine the value of V.
Measuring porosity in a gaseous fluid is tough. Water-filled pores are used to calibrate the
neutron porosity. Gas molecules are not as dense as those of water or oil. When gas-filled, the
neutron instrument will therefore detect a low porosity. Conversely, the density porosity will
register at a high value. They should read almost the same in the adjacent water or oil leg.
As a result, in the case of gas, this "crossover" of the two traces can be used to differentiate
between oil and gas.
Φ =
𝒑𝒐𝒓𝒆 𝒗𝒐𝒍𝒖𝒎𝒆
𝒃𝒖𝒍𝒌 𝒗𝒐𝒍𝒖𝒎𝒆
=
𝒃𝒖𝒍𝒌 𝒗𝒐𝒍𝒖𝒎𝒆−𝒈𝒓𝒂𝒊𝒏 𝒗𝒐𝒍𝒖𝒎𝒆
𝒃𝒖𝒍𝒌 𝒗𝒐𝒍𝒖𝒎𝒆
Type of methods and methoention of procedure of any method
1- Saturation methods
A method used in soil science and geology to ascertain a material's porosity is called the
saturation method. This technique involves entirely filling all of the vacuum spaces in a
sample of the material with a fluid, usually water. Together with the sample's overall
volume, the volume of fluid needed to saturate it is measured.

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Saturation methods Procedure
1. Simplicity: The saturation method is very easy to perform in a laboratory setting and
requires very little equipment, which saves setup time and expenses.
2. Accuracy: This technique yields measurements of porosity that are accurate, usually to
within a few percentage points, guaranteeing dependable information for scientific and
engineering study.
3. Versatility: The saturation method is appropriate for a variety of sectors and research
fields since it can be used with a broad range of materials, such as rocks, soils, ceramics, and
polymers.
4. Cost-effectiveness: The saturation method is reasonably priced when compared to more
advanced technologies, such imaging or scanning techniques, making it affordable for
researchers and engineers on a tight budget.
5. Speed: Saturation tests can be finished rather rapidly, enabling speedy porosity assessment
in contrast to other techniques that might take more time.

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2- Gravimetric Method (Archimedes MethoD
The gravimetric approach, sometimes referred to as the weight method, weighs a material
both before and after pore fluids are removed in order to calculate how porous it is. Using this
technique, the initial weight of the substance is determined by first weighing a dry sample of
the material. Subsequently, the specimen is saturated with a recognized fluid, such water, and
its saturated weight is determined by weighing it once more.
𝑉 𝑝 = Pore volume cm3
𝑊 𝑠𝑎𝑡 = Weight of core saturated with fluid g
𝑊 𝑠𝑢𝑏 = Weight of saturated sample submerged in water g
𝑊 𝑑𝑟𝑦 = Weight of dry core g
𝜌 𝑓 = Density of saturated fluid gm/cm
Gravimetric Method (Archimedes Method) Procedure
1. Initial Weighing: Using a balance, weigh the dry sample precisely. Make a precise note of
the starting weight.
2. Saturation: Use a known fluid, like water or mercury, to completely saturate the sample.
This can be accomplished by submerging the sample in the liquid or by forcing the fluid into
the pores with pressure or vacuum.
5. Sample Preparation: Prepare a representative sample of the material whose porosity you
want to measure. Ensure that the sample is clean and free from any contaminants that could
affect the results.
6 Initial Weighing: Weigh the dry sample using a balance with high precision. Record the
initial weight accurately.

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7. Saturation: Completely saturate the sample with a known fluid, such as water or mercury.
This can be done by immersing the sample in the fluid or by applying vacuum or pressure to
force the fluid into the pores.
3- Gas Expansion Method
Boyle's law, or the ideal gas law, is the foundation of this technique. At atmospheric pressure
P, the rock is sealed inside a container with a specified volume V (Figure 5.5). A valve
connects this container to a second container with a known volume (V2) and known pressure
(P2) that holds gas. The gas pressure in the two volumes equalizes to P3 when the valve
connecting them is gently opened to maintain system isothermia.
P, (Vi-Vs) + P2 V2 = P3(V,+ V2- Vs)
Figure5-5
Gas Expansion Method procedure
1. Preparing the Sample: Get a representative sample of the substance whose porosity you
wish to gauge. Make sure the sample is pure and devoid of any impurities that can taint the
outcomes.
2. Sample Conditioning: To guarantee consistency and accuracy in the measurements,
condition the sample to the desired temperature and pressure conditions, usually room
temperature and atmospheric pressure.

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3. Gas Introduction: Fill the sample's pores with a known amount of gas, such as nitrogen or
helium. This can be accomplished by submerging the sample in a gas-filled chamber or by
utilizing a gas displacement equipment.
4. Pressure Measurement: Using a pressure gauge or a manometer, determine the sample's
internal pressure both before and after the gas is introduced. Make certain that the
measurements of pressure .
Advantages and disadvantages :
Saturation methods Advantages and disadvantages :
Advantages
1. Easy and Economical: The saturation method is a simple and economical choice for
porosity measurements, especially for academics or enterprises with tight budgets, as it
usually takes little in the way of tools and resources.
2. Versatility: The saturation approach can be used in a variety of contexts and fields,
including geology, soil science, and material science. It can be used to a broad range of
materials, including rocks, soils, ceramics, and polymers.
3. Accuracy: The saturation method can yield precise and trustworthy results for measures of
porosity when used with caution. The porosity of the sample can be precisely determined by
researchers by saturating it with a known fluid and measuring the volume of fluid absorbed.
Disadvantages
1. Restricted to Connected Pores: Materials with interconnected pores are the main
candidates for the saturation approach. When measuring porosity in materials with closed or
isolated pores, it could underestimate porosity.
2. Density Contrast Requirement: To guarantee an accurate measurement, this approach
needs a sizable density contrast between the material and the saturating fluid. The
determination of porosity may be less accurate if the density contrast is minimal
.3. Difficulties in Sample Preparation: Saturation sample preparation can be labor-intensive
and time-consuming, especially for materials that are heterogeneous or have irregular shapes.
It can be difficult to ensure total saturation across the sample.4. Possible Sample Damage:
When a sample is saturated with some liquids, like water, it may swell or change in other
ways, which could lead to an incorrect porosity measurement.

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Advantages and disadvantages Gravimetric Method (Archimedes Method)
ADVANTEGS
1. High Accuracy: For porosity measurements, the gravimetric approach usually yields
findings that are very accurate. Researchers can get exact information on the porosity of a
sample by measuring the weight of the pore fluid that the sample absorbs.
2. Broad Applicability: This technique works with a variety of materials, such as soils,
rocks, polymers, ceramics, and other porous solids. Because of its adaptability, it can be
used to determine porosity in a variety of domains, including engineering, geology, soil
science, and materials science.
3. Easy Process: The gravimetric method requires little equipment and experience, and it
is a rather simple procedure to carry out.
Disadvantages
1. Labor-intensive Sample Preparation: When dealing with heterogeneous or
irregularly shaped materials, sample preparation for gravimetric analysis can be a labor-
intensive and time-consuming process. It can be difficult to ensure total saturation across
the sample.
2. Potential Sample Damage: The sample may swell or change in characteristics after
being saturated with some liquids, particularly water. This could result in imprecise
assessments of the sample's porosity. Furthermore, there is a chance that the sample will
be harmed if it is handled roughly or brittlely throughout the saturation process.
3. Impact of Surface Tension: Surface tension effects can skew saturation measurements
and cause inaccuracies in porosity assessments, particularly in materials with fine grained
structure.
Gas Expansion Method Advantages and disadvantages
Advantages
1. High Precision: For tests of porosity, the gas expansion method usually yields results that
are quite exact. Through the use of sophisticated technology to measure pressure changes,
researchers can accurately determine the porosity of the sample.
2. Applicable to a Wide Range of Materials: A variety of materials, such as rocks, soils,
ceramics, polymers, and other porous solids, can be treated using this technique. Because of
its adaptability, it can be used to determine porosity in a variety of domains, including
engineering, geology, soil science, and materials science.
3. Non-destructive Testing: Gas expansion is a non-destructive method, which means that
the sample is not harmed while being measured.

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Disadvantages
1-Complexity of Equipment: The equipment needed for gas expansion testing includes
specialized tools including control systems, gas cylinders, and pressure sensors, all of which
can be costly to buy and maintain. Accurate findings can also be obtained only with adequate
instrument setup and calibration
2. Potential Sample Damage: When gas is introduced into a sample, it can expand or change
in certain ways, which can lead to imprecise readings of the sample's porosity. To prevent the
sample from being harmed during the gas introduction procedure, caution must be exercised.
3. Limited Applicability to Specific Materials: Due to the gas's potential inability to enter
the sample deeply, gas expansion may not be appropriate for materials with closed pores or
extremely low porosity.
Calculation
Example 1
An irregular piece of sandstone is 35.25 grams in mass. When coated with varnish, its mass
increased to 36.55 grams. Compute the rock porosity if the coated sample displaces 15.7 ml of
water when fully submerged. ρg = 2.65 g/cm3
, ρw = 1.00 g/cm3
, ρv = 1.80 g/cm3
.
Solution
Vg = 35.25 / 2.65 = 13.30 cm3
Vv = (36.55 – 35.25) / 1.80 = 0.72 cm3
Vb = 15.70 – 0.72 = 14.98 cm3
ϕ = (14.98 – 13.3) / 14.98 = 0.112 = 11.2%
Note: This value is the absolute porosity.
Example 2
The varnish coating on the sample of example 1 was removed and the sample was submerged
in water. When air bubbling stopped, the sample was weighed while suspended in water. It
weighed 21300 dynes. Assume that you don't know the rock composition, compute the rock
porosity.
Solution

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Weight of sample in air = 35.25 x 980 = 34,545 dynes
Weight of sample in water = 21,300 dynes
Weight of displaced water = 34545 – 21300 = 13,245 dynes
Volume of displaced water = 13245 / (980 x 1) = 13.52 cm3
Vg = 13.52 cm3
ϕ = (14.98 – 13.52) / 14.98 = 0.097 = 9.7%
Note : This value is the effective porosity
Bulk Volume Calculated by Displacement:
Example 3
A core sample coated with paraffin immersed in a container of liquid displaced 10.9 cm3 of
the liquid. The weight of the dry core sample was 20.0 g, while the weight of the dry sample
coated with paraffin was 20.9 g. Assume the density of the solid paraffin is 0.9 g/cm3 Calculate
the bulk volume of the sample.
Solution
Weight of paraffin coating, Wparaffin = Weight of dry core sample coated with paraffin - Weight of dry core sample
Wparaffin = 20.9 g - 20.0 g = 0.9 g
Volume of paraffin coating = Weight of paraffin / density of paraffin
Volume of paraffin coating = 0.9 g / 0.9 g/cm3 = 1.0 cm3
Bulk volume of core sample = (Bulk volume of core coated with paraffin) – (volume of paraffin)
Vb = 10.9 cm3 - 1.0 cm3 = 9.9 cm3

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Example 4
Calculating the Matrix Volume and Porosity of a Core Sample Using the Displacement Method
The core sample from Example 3 was stripped of the paraffin coat, crushed to grain size, and
immersed in a container with liquid. The volume of liquid displaced by the grains was 7.7 cm3.
Calculate the matrix volume and the core porosity. Is this effective porosity or total porosity?
(It is total porosity).
Example 5
Archimedes Method of Calculating Porosity a Core Sample Using the gravimetric method
with the following data, calculate the pore and bulk volumes and the porosity. Is this
porosity total or effective?
Dry weight of sample, W dry = 427.3 g
Weight of sample saturated with water, W sat = 448.6 g
Density of water (𝜌 f ) = 1.0 g/cm3
Weight of saturated sample submerged in water, W sub = 269.6 g

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Result and Discussion
1) How may porosity be determined by saturation?
A1) After cleaning the core sample, we put it in the sample container and inject water into it
under high pressure. The volume of the injected water equals the pore volume of the connected
pores, allowing the porosity to be computed.
Q2) What is the purpose of using dead volume sets in this experiment?
A2) Depending on the porosity of the rock, they are utilized to lessen the exposed area to the
compressible pressure by water, allowing the core sample to become more saturated with water.
Conclusion
In summary, porosity, which describes the volume of voids or empty spaces within a substance,
is a fundamental feature of materials. It is essential to many disciplines, including biology,
materials science, engineering, and geology. Porosity is crucial for many different applications
because it affects characteristics including permeability, strength, density, and fluid storage
capacity.

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References
1-Vocabulary.com (2019). porosity - Dictionary Definition. [online] Available at:
https://www.vocabulary.com/dictionary/porosity [Accessed 19 Oct. 2019].
2-Cosentino, L., 2001. Integrated Reservoir Studies. Paris: Editions TECHNIP.
3-Dandekar, A. Y., 2013. Petroleum Reservoir Rock and Fluid Properties, Second Edition. 2nd
ed. New York: CRC Press.
4-Vocabulary.com (2019). porosity - Dictionary Definition. [online] Available at:
https://www.vocabulary.com/dictionary/porosity [Accessed 19 Oct. 2019].
5-En.wikipedia.org. (2019). Porosity. [online] Available at:
https://en.wikipedia.org/wiki/Porosity [Accessed 9 Oct. 2019].