Petroleum engineering lab report

1. College of Engineering
Faculty of petroleum Engineering
Reservoir Rock Properties Laboratory
PENG211L
Electrical Properties System at Ambient
Name: Ruba Alsoheil - ID: 201801530
Submitted to: Dr. Jamil Mahfoud
Date: 1-13-2021

2. Table of Content:
List of Figures……………………………………………………………………………………...i
List of Tables……………………………………………………………………………………....ii
Chapter 1: Introduction……………………………………………………………………………1
1.1 Theory and Definitions………………………………………………………………………...1
1.2 Objective……………………………………………………………………………………....1
Chapter 2: Apparatus………………………………………………………………….…………...2
Chapter 3: Other Equipment..……………………………………………………………………...4
Chapter 4: Procedure…………………..…………………………………………….……………9
Chapter5: Calculations…………………………………………………………………………...11
Chapter 6: Results and Discussion………………………………………………………………..14
6.1 Table of Results……………………………………………………………………………....14
6.2 Discussion..………………………………………………………………………………......15
Chapter 7: Errors and Recommendations…………..……………………………………………17
7.1 Errors…………………………………………………………………………………………17
7.2 Recommendations..…………………………………………………………………………..17
Chapter 8: Conclusion……………………………………………………………………………18
References………………………………………………………………………………………..19

3. i
List of Figures:
Figure 2.1: EPS-A apparatus………………………………………………………………………2
Figure 3.1: Core Samples………………………………………………………………………….4
Figure 3.2: Ruler…………………………………………………………………………………...4
Figure 3.3: Spatula………………………………………………………………………………...4
Figure 3.4: Plastic Plate……………………………………………………………………………4
Figure 3.5: NaCl…………………………………………………………………………………...5
Figure 3.6: Beakers………………………………………………………………………………...5
Figure 3.7: Digital Balance………………………………………………………………………...5
Figure 3.8: Core Plug Saturator……………………………………………………………………6
Figure 3.9: Vacuum Dryer…………………………………………………………………………6
Figure 3.10: Thermometer…………………………………………………………………………7
Figure 3.11: Air Tank……………………………………………………………………………...7
Figure 3.12: Conductivity meter…………………………………………………………………..7
Figure 3.13: Glass Microfibers…………………………………………………………………….8

4. ii
List of Tables:
Table 5.1: Weight and the resistance of different cores………………………………………….11
Table 6.1: Effective porosity of different sample………………………………………………....14
Table 6.2: Resistance and resistivity of the different cores………………………………………14
Table 6.3: Properties of the core samples…………………………………………………………14

5. 1
Chapter 1: Introduction
1.1 Theory and Definitions:
Characterizing and determining the petrophysical properties of the reservoir rocks is very
important to understand the behavior of the fluids and identifying the volume of the hydrocarbon.
Rocks consists of grains and pores. In the reservoir, the pores are usually filled with fluids like gas
or oil and water. Hydrocarbons whether oil or gas are not conductors (Muggeridge,). Meanwhile,
the water which contains salts like NaCl and KCl is considered a conductor. This due to the fact
that when salts like NaCl are dissolved in water leads to the separation of the atoms into charged
ions 𝑁𝑎+
and 𝐶𝑙−
. At all times, the water in the voids of the reservoir rock has a certain type of
salt especially NaCl, so the conductivity in the rock depend on the current flow due to the ions in
the brine solution since the rock’s minerals’ conductivity is 10 times less than that of the brine
solution (Muggeridge,). The conductivity which is often denoted by “𝜅” depends on the pores’
geometry and structure.
1.2 Objective:
The main objective of this apparatus is to measure resistivity in order to derive formation factor,
tortuosity, and cementation factor.

6. 2
Chapter 2: Apparatus
Figure 2.1: EPS-A apparatus (Vinci Technologies, n.d.)
EPS-A apparatus is a very vital apparatus, for it aids in determine the resistance and in deriving
important petrophysical properties like formation factor, Archie saturation exponent, and
cementation factor m.
▪ Screen monitor: It shows the measurements of the resistivity for each core.
▪ Lid: It is a plastic cover which aids in preventing the core from drying due to external
environment.
▪ Core Seat: It holds the core.
▪ Piston: It pushes the core.
▪ Pressure Indicator: It indicates the pressure of the piston on the core.
▪ Electrode plate: Since the cores are non-metal, the electrode plates aids in transmitting
the current through the core assuring the continuity of the current.
Screen
Monitor
Power
Switch
Pressure Indicator
Regulator
Lid
Piston
Electrode plates
Core
Seat
Electrode set

7. 3
▪ Electrode set: assures the current flow where it measures the resistance of the core
▪ Power switch: It is responsible for turning the apparatus ON or OFF.

8. 4
Chapter 3: Equipment Used
Figure 3.1: Core samples
Figure 3.2: Ruler
Figure 3.3: Spatula
Figure 3.4: Plastic plate
Indiana
Dolomite Torrey

9. 5
Figure 3.5:NaCl Salt
Figure 3.6: Beakers
Figure 3.7: Digital Balance
200 ml
beaker
800 ml
beaker

10. 6
Figure 3.8: Core Plug Saturator
Figure 3.9: Vacuum dryer
Vacuum
pump
Vacuum
dryer’s
chamber
Power
button
Duration

11. 7
Figure 3.10: Thermometer (LegacyPro, n.d.)
Figure 3.11: Air Tank
Figure3.12: Conductivity meter (Wolfgang Priggen, n.d.)
Conductance
reading
Conductivity
probe

12. 8
Figure 3.13: Glass Microfibers (SSI, 2021)
▪ Core Samples: Dolomite, Indiana, and Torrey are the cores used in the experiment.
▪ Ruler: The dimensions, length and diameter, are measured by it.
▪ Spatula: used to add NaCl salt and mix it with distilled water
▪ Plastic Plate: contains the NaCl salt to be measured on the digital balance
▪ Beakers: contains the brine solution
▪ Digital Balance: to measure dry, saturated, and partially saturated weight of the cores
▪ Core Plug Saturator: used to saturate the cores which will be retrieved after 24-48 hours
▪ Vacuum Dryer: It dries the cores making them partially saturated if needed or completely
dry.
▪ Thermometer: Temperature of the brine is measured which should be equal to 25ºC
▪ Air Tank: Supplies the EPS-A apparatus with air in order to move the piston so that it can
hold the core
▪ Conductivity meter: It measures the conductance of the core by putting the conductance
probe in the solution.
▪ Glass Microfibers and pads: It assures the passage of brine solution from side to side.

13. 9
Chapter 4: Procedure
▪ Prepare the brine solution where the first step is to calibrating the digital balance and using
a spatula put 36g of salt, KCl, on a plastic plate
▪ Mix the 36g of KCl using a spatula with 1000ml of distilled water which is in the beaker
▪ Using a ruler measure the dimensions, length and diameter, of the chosen cores which are
dolomite, Indiana, and Torrey
▪ Plug and turn ON the digital balance and measure the cores’ dry weight
▪ Put the core in the chamber of the cores plug saturator and follow the steps required to
saturate the cores with brine solution
▪ After 24 or 48 hours retrieve the cores from the core chamber of the core plug saturator
▪ Roll them on a tissue to get rid of extra liquid on the surface
▪ Then, put the saturated cores in the digital balance to measure their saturated weight
▪ The conductivity of the brine solution is measure by the conductivity meter by putting dip
conductivity probe in the solution
▪ Measure the temperature of the brine solution which should be equal to the room
temperature 24ºC
▪ It should be noted that the procedures should be done fast to prevent any errors in the
resistance’s values
▪ Assure that the switch responsible for holding the core between the two electrodes is OFF
▪ In the brine solution, immerse two glass microfibers pads and stick them with the pads on
the sides of the electrode plate
▪ Open the lid and put the core on the core seat

14. 10
▪ The piston moves where it holds the core after opening the air cylinder which is connected
to EPS-A apparatus
▪ Put the electrode set on the core
▪ Turn ON the apparatus and switch the valve ON to tightly hold the core by the piston
▪ The lid is closed
▪ Then, the core’s resistance is measured and noted by reading the value on the screen
▪ Turn OFF the switch
▪ Open the lid, the electrode set is then removed
▪ Retrieve the core from the core seat
▪ Repeat the same step for the remaining cores
▪ Put the cores in the vacuum dryer to desaturate the cores partially
▪ Measure the weight of the partially saturated cores using a digital balance
▪ Repeat the procedure mentioned above to measure the resistance of the partially saturated
cores
▪ Turn OFF the switch to retrieve the core, and unplug the apparatus
▪ Close the air cylinder
▪ The cores are placed in a vacuum dryer to completely dry them
▪ Clean the equipment used and the place them in place

15. 11
Chapter 5: Calculations
The first step is to calculate the bulk volume of the cores that have the same diameter 2.5 cm and
length 5 cm (0.05m)
𝑉𝑏𝑢𝑙𝑘= 𝜋 𝑟2
ℎ= 𝜋× 1.252
× 5 =24.53 cm3
A= 𝜋 𝑟2
= 𝜋× 1.252
=4.92 cm2
(4.92× 10−4
m2
)
Table 5.1: Weight and the resistance of different cores
Saturated core Desaturated core
Sample Dry weight (g) Weight (g) Resistance (Ω) Weight (g) Resistance (Ω)
Silurian 63 72 3500 65 3800
Torrey 58 66 320 61 400
Indiana 56 64 650 60 1000
Then, calculate the volume of the pore of Silurian, in order to calculate the effective porosity
𝑉
𝑝𝑜𝑟𝑒=
𝑆𝑎𝑡𝑢𝑟𝑎𝑡𝑒𝑑 𝑤𝑒𝑖𝑔ℎ𝑡−𝐷𝑟𝑦 𝑤𝑒𝑖𝑔ℎ𝑡
𝐷𝑒𝑛𝑠𝑖𝑡𝑦 𝑜𝑓 𝑠𝑜𝑙𝑢𝑡𝑖𝑜𝑛
=
72−63
1.02 𝑔/ 𝑐𝑚3
= 8.82 𝑐𝑚3
∅ =
𝑉𝑝𝑜𝑟𝑒
𝑉𝑏𝑢𝑙𝑘
=
8.82
24.53
= 0.36 (35%)
The conductivity, 𝜅, is the reciprocal of the resistivity:
𝜅 =
1
𝑅𝑜
(equation 1)
So, the resistivity of the brine solution is equal to 0.1538 Ω.m at 24ºC
𝑅𝑤 =
1
𝜅
=
1
6.5 𝑆/𝑚
=0.1538 Ω.m
𝑅 = 𝑅𝑟𝑒𝑓 [1 + 𝑎(𝑇 − 𝑇𝑟𝑒𝑓)] (equation 2)
▪ 𝑇𝑟𝑒𝑓 is the temperature at 20ºC
▪ 𝑅𝑟𝑒𝑓 is the resistivity at 20 ºC

16. 12
𝑅 = 𝑅𝑟𝑒𝑓 [1 + 𝑎(𝑇 − 𝑇𝑟𝑒𝑓)]; 𝑅𝑟𝑒𝑓𝑤 =
0.1538
[1+0.0188(𝑇−𝑇𝑟𝑒𝑓)]
= 0.1430 Ω.m (at 20 ºC)
𝑅𝑜 = 𝑅
𝐴
𝑙
(equation 3)
▪ R is the resistance (Ω)
▪ A is the cross-sectional area of the sample (𝑚2
)
▪ L is the length of the sample (m)
Resistivity of saturated Silurian at 24 ºC
𝑅𝑜. 𝑠 = 𝑅
𝐴
𝑙
=3500
4.92×10−4
0.05
=34.44 Ω.m
𝑅𝑟𝑒𝑓.𝑠 =
𝑅𝑜
[1+𝑎(𝑇−𝑇𝑟𝑒𝑓)]
=
34.44
[1+0.0188(24−20)]
= 32.03 Ω.m (at 20 ºC)
Resistivity of desaturated Silurian at 24 ºC
𝑅𝑜. 𝑑 = 𝑅
𝐴
𝑙
=3800
4.92×10−4
0.05
=37.39 Ω.m
𝑅𝑟𝑒𝑓.𝑑 =
𝑅𝑜
[1+𝑎(𝑇−𝑇𝑟𝑒𝑓)]
=
37.39
[1+0.0188(24−20)]
= 34.77 Ω.m (at 20 ºC)
Calculate the formation factor
𝐹𝑟 =
𝑅𝑜
𝑅𝑤
(equation 4)
▪ Ro is the core’s resistivity when saturated with brine fully (Ω.m)
▪ Rw is the resistivity of the brine solution (Ω.m)
𝐹𝑟 =
𝑅𝑜
𝑅𝑤
=
32.03
0.1430 Ω.m
=240.83 (at 20 ºC)
𝐹𝑟 = 𝑎∅−𝑚
(equation 5)
▪ Archie’s coefficient, a (unitless)
▪ Cementation factor, 𝑚 (unitless)
▪ Porosity, ∅ (unitless)

17. 13
𝐹𝑟 = 𝑎∅−𝑚
; m =
ln (𝐹𝑟)
ln (∅)
=
−ln (240.83 )
ln (0.36)
=5.36(at 20 ºC)
Calculate tortuosity (unitless)
𝑇 = ∅ × 𝐹𝑟= 0.36 × 240.83 =86.69
Calculate the resistivity index, I, (unitless)
𝐼 =
𝑅𝑡
𝑅𝑜
(equation 6)
𝐼 =
𝑅𝑡
𝑅𝑜
=
34.77
32.03
=1.085 (at 20ºC)
𝑉𝑤𝑎𝑡𝑒𝑟 =
𝐷𝑒𝑠𝑎𝑡𝑢𝑟𝑎𝑡𝑒𝑑 𝑤𝑒𝑖𝑔ℎ𝑡 − 𝑑𝑟𝑦 𝑤𝑒𝑖𝑔ℎ𝑡
𝑑𝑒𝑛𝑠𝑖𝑡𝑦 𝑜𝑓 𝑏𝑟𝑖𝑛𝑒
=
65 − 63
1.02
= 1.96 𝑐𝑚3
Water saturation, Sw, which is unitless equation is shown.
Sw =
𝑉𝑤𝑎𝑡𝑒𝑟
𝑉𝑝𝑜𝑟𝑒
=
1.96
8.82
= 0.22

18. 14
Chapter 6: Results and discussion
6.1 Results:
Table 6.1: Effective porosity of different sample
Saturated
core
Desaturated
core
Sample Dry
weight (g)
Weight (g) Weight (g)
𝑉
𝑝𝑜𝑟𝑒 (cm3
)
𝜙
(unitless) 𝜙 (%)
Silurian 63 72 65
8.82 0.36 35.97
Torrey 58 66 61 7.84 0.32 31.97
Indiana 56 64 60 7.84 0.32 31.97
Table 6.2: Resistance and resistivity of the different cores
Saturated
core
Desaturated
core
At 24 ºC At 20 ºC
Sample Resistance
(Ω)
Resistance
(Ω)
Resistivity
of
saturated
core
(Ω. m)
Resistivity
of
desaturated
core
(Ω. m)
Resistivity
of
saturated
core
(Ω. m)
Resistivity
of
desaturated
core
(Ω. m)
Silurian 3500 3800
34.34 37.29 31.94 34.68
Torrey 320 400
3.14 3.93 2.92 3.65
Indiana 650 1000
6.38 9.81 5.93 9.13
Table 6.3: Properties of the core samples
Sample Fr
(unitless)
m
(unitless)
I
(unitless)
T
(unitless) 𝑉𝑤𝑎𝑡𝑒𝑟 (cm3
) Sw (unitless)
Silurian 223.37 5.29 1.09 80.35 1.96 0.22
Torrey 20.42 2.65 1.25 6.53 2.94 0.38
Indiana 41.48 3.27 1.54 13.26 3.92 0.50
At 20 ºC

19. 15
6.2 Discussion:
The resistivity and the conductivity, the reciprocal of resistivity (equation 1), depend on the
geometry of the voids in which brine water is in. The conductivity increases when brine water in
the rock increases which depend on the effective porosity or the interconnected pores. So,
resistivity increases when effective porosity decreases since the volume of the natural electrolyte
filling the pores decrease (Sharma, 1997). However, the comparison of table 6.1 and table 6.2
shows that the rock, Silurian, which have highest effective porosity (0.36) has the highest
resistance and resistivity of saturated cores (34.34 Ω. m ) compared with Torrey that has the lowest
resistivity (3.14 Ω. m) and effective porosity (0.32). This shows that there are certain errors done
in the experiment which are developed in Chapter 7.
Moreover, temperature and the volume of the cores in the pores affect the resistivity of the core.
When the temperature rises, this leads to an increase in the mobility of the ions which are in this
experiment 𝑁𝑎+
and 𝐶𝑙−
. When the ions’ mobility increases, the conductivity increases, and the
resistivity decreases (Sharma, 1997). When the volume of brine solution in the cores decreases,
resistivity increases. The resistivity of the saturated core, Silurian, is 31.94 Ω. m at 20 ºC While,
the resistivity of the desaturated core, Silurian, is 34.68 Ω. m at 20 ºC which is more. Also, the
salinity of the water affects conductivity and resistivity, since when the concentration of salt
increases, conductivity increases (Chopra, 2010). Also, processes that decreases the percentage of
the interconnected pores in the rock increases resistivity like compaction and mineral participation
(Heimmer, 1996). While, dissolution and fracturing due to tectonic movements decrease resistivity
(Heimmer, 1996).
Furthermore, as shown in equation 4, the formation factor is directly proportional to the resistivity
of fully saturated core. So, the factors which affect the resistivity impact the formation factor.

20. 16
Silurian has the highest resistivity of saturated cores (34.34 Ω. m ) and the highest formation factor
223.37. The formation factor is related to porosity and pore structure (Tiab & Donaldson, 2012).
Cementation is impacted by the type, the amount, and the way the particles are distributed. Also,
the cementation factor, m, is related to porosity and formation factor as shown in equation 5. The
cementation factor depends on the type of the rock, structure of the pore, and its distribution. For
instance, carbonate cementation factor ranges between 2.5 and 5. Whereas, in sandstone it ranges
between 1.5 and 2.5 (Bensabt, 2017). Torrey (m=2.65) which is a sandstone is slighter higher than
the range (Torrey Pine States Natural Reserve, 2021).
Tortuosity as shown in equation 6 is directly proportional to porosity and formation factor, for
Silurian has the highest tortuosity 80.35. Low porosity and high formation factors increase
tortuosity which is dominantly found in rocks that have coarse grains (Salem, 1993). Also, the
shape of the grain affect tortuosity (Salem, 1993). For instance, rocks with spherical grains has
lower tortuosity than the angular ones. Saturation depends on the volume of the pore and the water
volume which is related to effective porosity. Also, high water saturation means low resistivity.
For instance, Silurian has the lowest water saturation 0.22 and the highest resistivity.

21. 17
Chapter 7: Errors and Recommendations
7.1 Errors:
▪ Not rolling the cores on a tissue after retrieving the cores from the core plug saturator which
leads to smaller resistivity
▪ Not putting the glass microfibers on the two electroplates which decreases the conductivity
▪ Lid is open which decreases the saturation of the core
▪ The electrode set is not appropriately placed leading to errors in the measurement
▪ Not opening the air tank leading to the piston not being pushed and errors in the
measurement
▪ The room’s temperature is not exactly 24 ºC
7.2 Recommendations:
▪ Roll the cores on a tissue after their retrieve from core plug saturator
▪ Stick glass microfibers on the electroplates
▪ Close the lid to ensure that the core does not dry
▪ Placing the electrode set on the core appropriately
▪ Open the tank before turning the power switch ON
▪ Take into account if the temperature is not exactly 24 ºC

22. 18
Chapter 8: Conclusion
The electrical properties like resistivity and conductivity are very important especially in
petroleum industry. Moreover, measuring resistivity helps identifying the saturation of the water
since high resistivity means low water saturation. This aids in identifying the irreducible water
saturation and the transition zone helping in identifying the place in which the well should be
drilled. Formation factor, tortuosity, and the resistivity index are all related to resistivity which is
affected by porosity and the geometry of the pores (Jiang et al., 2011).

23. 19
References
Bensabat, J. et al. (2017). Geological Storage of CO2 in Deep Saline Formations. Sweden:
Springer.
Chopra, S. (2010). Heavy Oils: Reservoir Characterization and Production Monitoring. Tulsa:
Society of Exploration Geophysicists.
Heimmer, D. H. (1996). Near-surface, High Resolution Geophysical Methods for Cultural
Resource Management and Archeological Investigations. Colorado: U.S. Department of Interior.
Jiang, L. et al. (2011). Study of different factors affecting the electrical properties of natural gas
reservoir rocks based on digital cores. Journal of Geophysics and engineering.
DOI: 10.1088/1742-2132/8/2/021
LegacyPro. (n.d.). Legacy Pro 6 Glass Thermometer. Retrieved from: Legacy Pro 6" Glass
Thermometer 62010 B&H Photo Video
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Salem, H. S. (1993). Geological Survey of Canada, Open File 2686. Bedford: Atlantic Geoscience
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Sharma, P. V. (1997). Environmental and Engineering Geophysics. New York: Cambridge
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per-box
Tiab, D. &, Donaldson, E. C. (2012). Petrophysics: Theory and Practice of Measuring Reservoir
Rock and Fluid Transport Properties. Waltham: Gulf Professional Publishing.

24. 20
Torrey Pine States Natural Reserve. (2021). Rock Formations. https://torreypine.org/nature-
center/geology/rock-formations/
Wolfgang Priggen. (n.d.). G 1420, High-Resolution Ultra Clean Water Conductivity Meter.
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