Petroleum engineering lab report

1. College of Engineering
Faculty of petroleum Engineering
Reservoir Rock Properties Laboratory
PENG211L
Core Plug Saturator
Name: Ruba Alsoheil - ID: 201801530
Submitted to: Dr. Jamil Mahfoud
Date: 27-Dec-2020

2. Table of Content:
List of Figures……………………………………………………………………………………...i
List of Tables……………………………………………………………………………………....ii
Chapter 1: Introduction……………………………………………………………………………1
1.1 Theory and Definitions………………………………………………………………………...1
1.2 Objectives……………………………………………………………………………………...2
Chapter 2: Apparatus………………………………………………………………….…………...3
Chapter 3: Other Equipment..……………………………………………………………………..4
Chapter 4: Procedure………………………………………………………………………………6
Chapter 5: Calculation……………………………………………………………………………..7
Chapter 6: Results and Discussion…………………………………………………………………9
6.1 Table of Results……………………………………………………………………………......9
6.2 Discussion…………………………………………………………………………………......9
Chapter 7: Errors and Recommendations………………………………………..………………12
7.1 Errors…………………………………………………………………………………………13
7.2 Recommendations..…………………………………………………………………………..13
Chapter 8: Conclusion……………………………………………………………………………14
References………………………………………………………………………………………..15

3. i
List of Figures:
Figure 1.1: CST gun……………………………………………………………………………….3
Figure 1.2: The functioning of CST gun……………………….………………………………….3
Figure 1.3: Conventional Rotary Coring Apparatus……………………………………………….4
Figure 2.1: MVS-2.………………………………………………………………………………..5
Figure 3.1: Core samples………………………………………………………………………….7
Figure 3.2: Vacuum dryer…………………………………………………………………………7
Figure 3.3: Digital Balance………………………………………………………………………..8
Figure 3.4: Salt used……………………………………………………………………………….8
Figure 3.5: Beakers………………………………..………………………………………………8
Figure 3.6: Spatula………………………………..…….…………………………………………9
Figure 3.7: Plastic plate………………………………..…….……………………………………9
Figure 3.8: Dead volume blocks………………………………..…………………………………9
Figure 3.9: Wrench………………………………..…….…………………………………………9
Figure 3.10: Funnel………………………………..…….………………………………………..9
Figure 3.11: Ruler………………………………..…….…………………………………………10
Figure 6.1: Pores in carbonate reservoir………………………………..…….….………………17
Figure 6.2: Cubic packing………………………………..…….………………………………..17

4. ii
List of Tables:
Table 5.1: The dimensions of the cores………………………………………………………….14
Table 5.2: The weight, interconnected pore volume, and porosity of the cores…………………14
Table 6.1: The effective porosity of the core samples……………………………………………16

5. 1
Chapter 1: Introduction
1.1 Theory and definitions:
Understanding and determining the petrophysical properties like porosity, permeability, and fluid
saturation of a reservoir rock aid in the determination of the capacity or the volume of the
hydrocarbon in place which leads to the identification of the commerciality of the reservoir rock.
In order to characterize the reservoir, reservoir engineers measure the petrophysical properties.
One of these methods is well logging which does not measure the petrophysical properties in a
straight-forward manner (Dandekar, 2011). In order to measure porosity indirectly, there are three
types of logs which are sonic, density, and neutron (Dandekar, 2011). For instance, sonic logs
record the time needed for pulse to be detected by a receiver, so a large duration indicates that a
high porous formation is present.
Cores are significantly important since they influence the decisions related to the exploration,
development, and production of oil and gas, for they can inform the reservoir scientist regarding
various petrophysical parameters (Tavakoli, 2018). In order to get cores from the formations,
coring methods are implemented. During drilling through the formation, conventional rotary
coring method is used where the core bit cut cylindrical core that is received by the aluminum
inner barrel and is held due to the mud circulation between the outer and inner barrel (Austen,
1983). Another coring method is side wall coring which is usually done after the hole is drilled
(EXLog staff, 1985). Side coring is usually done by a CST gun like figure 1.1 that fires a hollow
bullet which retrieves a cylindrical core as shown in figure 1.2 that is due to an electrical command
from the panel on the surface (EXLog staff, 1985). When comparing the coring methods, it can be
deduced that side wall coring has a lot of better contributions and characteristics than the
conventional coring method. For instance, side coring is less costly, cut and transport samples

6. 2
faster, and the samples can be tested immediately (Gaafar et al., 2015). Moreover, cores should be
handled and preserved carefully, for mishandling the core samples can lead to major difference in
the cores’ characteristics. Also, different rock types require different preservations and handling
methods (Ubani, 2012). For instance, mishandling cores inappropriately leads to additional
fractures and contaminations if preserved in a reactive material.
The analysis of the cores has developed to a phenomenal extent the past years. For instance, in the
past scientists used to characterize cores by using visuals, taste, and smell (Monicard, 1980). The
vital information provided by core analysis are related to permeability, capillary pressure and
acoustic velocity (Gaafar et al., 2015). One of the most important petrophysical parameters is
porosity. One of the equipment which measure porosity is core plug saturator which is unlike
helium porosimeter since it uses liquids saturation of the rock in order to measure effective
porosity, ∅𝑒𝑓𝑓.
∅𝑒𝑓𝑓 =
𝑉
𝑝
𝑉𝑏𝑢𝑙𝑘
=
𝑉𝑏𝑢𝑙𝑘 − 𝑉𝑔𝑟𝑎𝑖𝑛
𝑉𝑏𝑢𝑙𝑘
=
𝑉𝑖𝑛𝑡𝑒𝑟
𝑉𝑏𝑢𝑙𝑘
… . . (equation 1)
Where 𝑉𝑖𝑛𝑡𝑒𝑟 =
Saturated weight−Dry weight
𝜌𝑙𝑖𝑞𝑢𝑖𝑑 𝑢𝑠𝑒𝑑
▪ 𝑉
𝑝, volume of the voids (cm3
)
▪ 𝑉𝑏𝑢𝑙𝑘, volume of the core (cm3
)
▪ 𝑉𝑖𝑛𝑡𝑒𝑟, volume of the interconnected pores (cm3
)
1.2 Objective: Core plug saturator is used to saturate the core with liquid under an appropriate
pressure to mimic lithostatic pressure where this allows to derive the volume of interconnected
core, and most importantly effective porosity using equation 1.

7. 3
Figure 1.1: CST gun (EXLog staff, 1985)
Figure 1.2: The functioning of CST gun (EXLog staff, 1985)

8. 4
Figure 1.3: Conventional Rotary Coring Apparatus (EXLog staff, 1985)

9. 5
Chapter 2: Apparatus
Figure 2.1: MVS-2K
▪ Stopper: used to close the flask making the flask a closed system
▪ Flask: Brine, oil, or even water can be contained in it, but in this experiment the saturating
fluid is brine
▪ Cap: used to close the saturation cell
▪ Saturation cell: The chamber where dead volume blocks and the core are placed in to
saturate the core. The maximum diameter’s core is 2 in and the maximum length is 12 in
(PMI, 2020).
▪ Guage pressure reading is related to saturation pressure
▪ Hand operated pressure pump or hand pressurized valve is used to force the brine to go
inside the core which is in the saturation cell
Tubes
Stopper
Vacuum
valve
Cap
Saturation valve
Saturation cell
Hand operated
pressure pump
Gauge pressure
reading
Bypass
valve
Flask

10. 6
▪ There are two tubes: The shorter one is called the vacuum tube which is used to vacuum
the system from any solution from any previous experiment. While the other one which is
longer is called the saturation tube which makes the liquid used to flow into the saturation
cell
▪ There are three valves which are the vacuum valve to vacuum the system, saturation valve
to allow the saturation of the system, the bypass valve is responsible for controlling the
pressure of the system.

11. 7
Chapter 3: Other Equiment
`
Figure 3.1: Core samples
Figure 3.2: Vacuum dryer
Vacuum
pump
Vacuum
dryer’s
chamber
Power
button
Torrey
Indiana
Dolomite
Berea
Duration

12. 8
Figure 3.3: Digital Balance
Figure 3.4: Salt used
Figure 3.5: Beakers
800 ml
beaker
200 ml
beaker

13. 9
Figure 3.6: Spatula
Figure 3.7: Plastic plate
Figure 3.8: Dead volume blocks
Figure 3.9: Wrench
Figure 3.10: Funnel (Storage Box, n.d.)

14. 10
Figure 3.11: Ruler
▪ Cores: Berrea, Silurian, Indiana, and Torrey are the cores used in the experiement.
▪ Vacuum dryer: This apparatus is used to dry out any droplets of water and to clean the
cores from dust and residuals left from previous experiments.
▪ Digital Balance: measuring the weight of the cores is done by it
▪ Beakers: used as a container to make brine
▪ Spatula: used to put salt on the plastic plate and to mix in order for the salt to dissolve
▪ Plastic plate: salt is placed on it
▪ Funnel: in order to prevent brine from falling outside the flask
▪ Dead volume blocks: The volume of the saturation cell is much larger than the volume of
the core, so dead volumes which have zero porosity are used to compensate for the needed
space. In this way less volume of brine is needed to fill the saturation cell.
▪ Wrench: unscrewing the cap
▪ Ruler: Cores’ different dimensions are measured

15. 11
Chapter 4: Procedure
▪ Measure the dimensions, diameter and length, of the cores using a ruler and record them
▪ Turn On the vacuum dryer
▪ Put the cores in a vacuum’s chamber to make sure that the core is dry
▪ Set the vacuum dryer’s duration to 40 sec and activate it
▪ While waiting for the cores to be dry, prepare the brine solution
▪ Bring a spatula and plastic plate
▪ Put the plastic plate on the digital balance and calibrate it
▪ Use the spatula and put salt, KCl, into the plastic plate until the digital balance reading is
36g
▪ 1 liter of distilled water is needed, so fill distilled beaker with 800 ml
▪ Then, fill another beaker with 200ml
▪ Add KCl using a spatula to the distilled water
▪ Mix it using a spatula until the all the KCL dissolve
▪ The density of the mixture will be 1.02
𝑔
𝑐𝑚3
⁄
▪ The vacuum dryer finished drying the core
▪ Take the cores from the vacuum chamber
▪ Measure each core dry weight using a digital balance
▪ Open the stopper
▪ Put a funnel and pour 800 ml of brine in the flask
▪ Make sure the saturation tube is below the liquid level and the vacuum tube is above the
liquid level
▪ Close the stopper

16. 12
▪ Open the saturation cell’s cap using a wrench
▪ Replace the rubber ring if needed
▪ Clean the cap from any residuals from previous experiments
▪ Put the appropriate core alongside with dead volumes
▪ Close the cap well
▪ Open the vacuum, bypass, and saturation valves
▪ Turn On the apparatus, core plug saturator
▪ Wait until there no bubbles seen in the flask, such it can be defined as vacuumed
▪ Turn Off the apparatus
▪ Close the vacuum and the bypass valves
▪ Open the stopper
▪ Apply pressure using the hand pressurized valve to urge the fluid to go inside the core
▪ Close saturation valve
▪ Wait twenty-four hours
▪ Close the stopper
▪ Open vacuum, bypass, and saturation valves
▪ Turn On the apparatus
▪ The Brine solution starts to go back to the flask from the saturation cell
▪ When the flow of liquid stops, close the vacuum valve
▪ Close the bypass and the saturation valves
▪ Turn OFF the apparatus
▪ The tubes should be above the liquid level
▪ Open vacuum and saturation valve

17. 13
▪ Use the wrench to unscrew the cap
▪ Retrieve the used core from the saturation cell
▪ Roll the core on a tissue to get rid of the extra droplets on the core’s surface
▪ Use the digital balance to measure the saturated weight
▪ Record the saturated weight
▪ Use the vacuum dryer to dry the cores
▪ Close the saturation cell after cleaning
▪ Close the cap
▪ Clean the used beakers and spatula
▪ Get rid of the brine solution and clean the flask

18. 14
Chapter 5: Calculation
Table 5.1: The dimensions of the cores
Core samples Diameter (cm) Length (cm) 𝑉𝑏(𝑐𝑚3
)
Berea 2.5 3.7 18.15
Silurian Dolomite 2.5 5 24.53
Indiana 2.5 5 24.53
Torrey 2.5 5 24.53
Table 5.2: The weight, interconnected pore volume, and porosity of the cores
Core samples Dry weight (g) Saturated weight
(g)
𝑉𝑖𝑛𝑡𝑒𝑟(𝑐𝑚3
) ∅eff
(unitless)
∅eff (%)
Berrea
Sandstone
37 47
9.80 0.54 54
Silurian
Dolomite
64 67
2.94 0.12 12
Indiana 56 65 8.82 0.36 36
Torrey 58 63 4.90 0.20 20
Calculate the total volume, bulk volume, in cm3
of the sample core, Silurian Dolomite
𝑉𝑏 =
𝐷2
𝜋 𝐿
4
▪ D is diameter of the core in cm2
▪ L is the length of the core in cm
𝑉𝑏 =
𝐷2𝜋 𝐿
4
=
2.52𝜋 5
4
= 24.53 cm3
Then, the interconnected volume of the core, 𝑉𝑖𝑛𝑡𝑒𝑟, is calculated.
𝑉𝑖𝑛𝑡𝑒𝑟 =
Saturated weight−Dry weight
𝜌𝑏𝑟𝑖𝑛𝑒
=
67−64
1.02
𝑔
cm3
⁄
= 2.94 cm3

19. 15
The last step is to calculate the effective porosity, ∅eff.
∅eff =
𝑉𝑖𝑛𝑡𝑒𝑟
𝑉𝑏
=
2.94
24.53
= 0.12 (12%)

20. 16
Chapter 6: Results and discussion
6.1 Results:
Table 6.1: The effective porosity of the core samples
Core samples 𝑉𝑖𝑛𝑡𝑒𝑟(𝑐𝑚3
) ∅eff (unitless) ∅eff (%)
Berrea Sandstone 9.80 0.54 54.02
Indiana 8.82 0.36 36
Torrey 4.90 0.20 20
Silurian Dolomite 2.94 0.12 12
6.2 Disscusion:
Table 6.1 shows that the effective porosity of Berrea Sandstone is the highest (54.02%). While the
effective porosity of Silurian Dolomite is lowest (12%). Effective porosity is the porosity of the
interconnected pores such that the isolated pores are not taken into consideration (equation 1), so
as the 𝑉𝑖𝑛𝑡𝑒𝑟 increases the ∅eff increases.
There are a lot of factors which affect the effective porosity of the rocks. There are two types of
porosity that are secondary and primary porosity. Primary is related to the original deposition,
while secondary is related to fractures due to tectonic pressure and vugs or cavities which is due
to the dissolution of the reactive grains. Furthermore, whether the rock is clastic, rocks formed due
to erosion, or carbonate, formed due to chemical participation give an idea about the dominant
type of porosity. Carbonate rocks like dolomite and Indiana’s have secondary porosity, for instance
a typical stress to cause fracture for consolidated carbonate ranges from 2000 psi to 37000 psi
(Kogel et al. 2006). Furthermore, dolomitization process affect the porosity in dolomite (Wang et
al., 2015). The dissolution of carbonate increases porosity, while the participation decreases
porosity. Typical porosity for carbonate rocks is shown in figure 6.1.

21. 17
Factors like grains’ size, shape, and uniformity, and type of packing or sorting affect porosity. For
instance, the highest porosity is when the grains are arranged in a cubic packing as shown in figure
6.2 (Dandekar,2011). Furthermore, in sandstone the main factor which decreases porosity is
cementation where minerals deposit between the pores. This can justify the reason why Torrey
sandstone has less porosity than berrea sandstone due the depositions of cement between the quartz
particle (Torrey Pine State Natural Reserve, 2020). In some cases, the cement dissolves creating
isolated pores, instead of interconnected pores. Also, as the depth increases, the lithostatic stress
increases which leads to rocks’ grains to be more compacted, so the porosity decreases. So, there
are a lot of factors which affect the ratio of porosity where usually sandstone has the highest
porosity which can be either primary or secondary, but it can fluctuate due to the previously
discussed factors.
Figure 6.1: Pores in carbonate reservoir (Monicard, 1980)
Figure 6.2: Cubic packing (Monicard, 1980)

22. 18
Chapter 7: Errors and Recommendation
7.1 Errors:
▪ The cores are not dryed well
▪ The saturation cell’s cap is not clean
▪ Forgetting to put a rubber ring around the cap to seal the saturation cell well
▪ The stopper is firmly closing the flask
▪ Forgetting to roll the cores over a tissue leading to an increase in the saturation weight
▪ Errors in measuring the dimensions of the core
▪ The weight of the salt is not exactly 36g leading to slightly different density
▪ Not waiting before retreiving the core leading to the core not being saturated well
7.2 Recommendatiom:
▪ Use a vacuum dryer to dry the core
▪ Clean the saturation cell well
▪ Make sure to replace the rubber ring around the cap
▪ Make sure the stopper and the tubes are placed well
▪ Roll the core over a tissue to get rid of the extra liquid particles on the surface of the core
▪ Make sure that the salt weight is 36g
▪ Wait 24 hours before retrieving the core

23. 19
Chapter 8: Conclusion
Core analysis reduces the uncertainties and the contingencies, but core analysis alone is not enough
to characterize the whole reservoir effectively and efficiently, so this is why it is paired with well
logging. Effective porosity is a vital parameter which helps understand the reservoir’s hydrocarbon
capacity. Porosity is impacted by various, many parameters like type of rock and shape of the
grains.

24. 20
References
Dandekar, A. Y. (2011). Petroleum Reservoir Rock and Fluid Properties. New York: Taylor &
Francis group.
Gaafar, G. R. et al. (2015). Overview of Advancement in Core Analysis and Its Importance in
Reservoir Characterization for Maximizing Recover. Evaluation of Low Resistivity Low Contrast
(LRLC) Pays of Some Malaysia Reservoirs. DOI: 10.2118/174583-MS
Kogal, J. E. et al. (2011). Industrial Minerals & Rocks: Commodities, Markets, and Uses. United
States of America: SME.
Monicard, R. P. (1980). Properties of Reservoir’s Rocks: Core Analysis. Paris: Editions Technips.
PMI. (2020). Manual Core Saturator. Retrieved from: Manual Core Saturator (rockcoreinc.com)
Storage Box. (n.d.). Funnel 17cm. Retrieved from:
https://www.storagebox.co.nz/garage/measuring-jugs-funnels-jars/funnel-17cm
Tavakoli, V. (2018). Geological Core Analysis: Application to reservoir characterization. Tehran:
Springer.
Torrey Pines State Natural Reserve. (2020). Torrey Sandstone. Retrieved from:
https://torreypine.org/nature-center/geology/rock-formations/torrey-sandstone/
Ubani, C. E. (2012). Advances in coring and core analysis for reservoir formation evaluation.
Nigeria: University of Lagos.
Wang, G. et al. (2015). Dolomitization process and its implications for porosity development in
dolostones. Journal of Petroleum Science and Engineering. DOI: 10.1016/j.petrol.2015.04.011