In this study, complete PVT lab experiments were done and then evaluate the most frequently used empirical black oil PVT correlations for application in the Middle East. Empirical PVT Correlations for Middle East crude oil have been compared as a function of commonly available PVT data. Correlations have been compared for: Bubble point pressure; solution gas oil ratio, oil formation volume factor, oil density, and oil viscosity. After evaluates the Empirical correlations the crude sample was characterized using different EOS to arrive at one EOS model that accurately describes the PVT behavior of crude oil produced.

1. Laboratory and Theoretical investigations of
petroleum reservoir fluid properties
New Correlation for Libyan Oil
By
Mohamed Lamoj
Libyan Petroleum Institute. Petroleum PVT Department. Al-siyahia. Libya
Academy of Higher Education. Department of Oil and Gas Engineering. Janzur. Libya
2022
Scientific Article

2. Abstract:
Understanding the PVT properties is very important to many kinds of petroleum determinations
like calculations of reservoir fluid properties; expect the future performance, selection of
enhanced oil recovery methods, and for production facilities design. Models for expecting
reservoir fluid properties has been increased attention during last decade by knowing reservoir
pressure and temperature, oil API gravity, and gas gravity.
In general, PVT properties are obtain from laboratory experiments but in some cases correlations
are used whenever experimentally derived PVT data are not available and data from local
regions are expected to give better approximation to estimated PVT values. Also, Equations of
State, EOS, are increasingly being used to model fluid properties of crude oil and gas reservoirs.
This technique offers the advantage of an improved fluid property prediction over conventional
black oil models. Once the crude oil or condensate fluid system has been probably characterized,
its PVT behavior under a variety of conditions can easily be studied. This description is then
used, within a compositional simulator, to study and choose among different scenarios.
In this study, complete PVT lab experiments were done and then evaluate the most frequently
used empirical black oil PVT correlations for application in the Middle East. Empirical PVT
Correlations for Middle East crude oil have been compared as a function of commonly available
PVT data. Correlations have been compared for: Bubble point pressure; solution gas oil ratio, oil
formation volume factor, oil density, and oil viscosity. After evaluates the Empirical correlations
the crude sample was characterized using different EOS to arrive at one EOS model that
accurately describes the PVT behavior of crude oil produced.
The multi-sample characterization method is used to arrive at one consistent model for crude oil
for the whole reservoir. The fluid sample is first analyzed for consistency to make sure that they
are representative of oil produced, and then it is used to obtain parameters for EOS model. The
tuning procedure for the EOS is done systematically by matching the volumetric and phase
behavior results with laboratory results.
Results showed some correlations gives good results and can be used with Libyan oil and some
gives high percentage of error.

3. NOMENCLATURE
Bo oil formation volume factor, bbl/STB
Bob oil FVF at bubble point pressure, bbl/STB
API stock-tank oil gravity, APIo
FVF formation volume factor
GOR gas oil ratio
OFVF oil formation volume factor
P pressure, psia
Pb bubble point pressure, psia
PVT pressure-volume-temperature
Rs solution gas-oil-ratio, SCF/STB
SCF standard cubic feet
STB stock tank barrel
g gas specific gravity (air = 1)
o oil specific gravity (water = 1)
T reservoir temperature, °R
gs gas gravity at the reference separator pressure
g gas gravity at the actual separator conditions of Psep and Tsep
Psep actual separator pressure, psia
Tsep actual separator temperature, °R
o viscosity of under-saturated oil, cp
ob viscosity of saturated oil, cp
od viscosity of the dead oil as measured at 14.7 psia and reservoir temperature, cp
ACRONYMS
bbl barrel
Bib binary interaction parameter
CCE constant composition expansion
CVD constant volume depletion
DL differential liberation
EOS equation of state
GOR gas oil ratio
GLR gas liquid ratio
SCF standard cubic feet
STB stock tank barrel
SW schmidt-wenzel E.O.S
PR peng-robinson E.O.S
RK redlick-kwong E.O.S
SRK soave-redlick-kwong E.O.S
a, b, c coefficient value of correlation

4. Objectives
This study aims to achieve these goals:
1- Understanding the main PVT experiments for reservoir fluids and learn the importance of
their design and results.
2- Using PVT analysis report to calculate oil physical properties, in this study
 Bubble Point Pressure, Pb
 Oil Formation Volume Factor, FVF, Bo
 Gas Oil Ratio, Rs
 Oil Density, ρo
 Oil Viscosity, μo
3- Using most of the Empirical PVT correlations to determination the previous sample physical
properties By design Excel software.
4- Evaluation the Empirical PVT correlations by Comparison the results from the observation
data from the lab experiments and the results getting from the correlations.
5- Understanding and training on Eclipse software just for PVTi software and understanding the
function of different E.O.S.
6- Test the ability of Equation of State for predicting the PVT properties by matching the PVT
lab data with different E.O.S.
7- Appreciate the need for E.O.S tuning, the role of experimental data and parameters used for
tuning.
8- Developed new PVT correlations for one Libyan oil field just for:
 Bubble Point Pressure, Pb
 Oil Formation Volume Factor, FVF, Bo
by using DataFit software.

5. Methodology:
Part One: Laboratory Analysis of Reservoir Fluids
In this study we select one Libyan crude oil which was heavy oil (Black oil) to do all routine lab
PVT experiments
For bottom hole sample the following sequence of PVT tests are proposed:
 Select most representative sample
 Flash to atmospheric conditions
 Constant mass study (PV Relation)
 Differential vaporization
 Separation test
 Viscosity determination
 Calculations
 Final report
Operating Procedures (main steps):
1) Set the bottle containing the sample to be run at vertical position.
2) Clean, evacuate the PVT cell at room temperature.
3) Connect steel line from the injection pump to the top of the cell making sure top cell
valve is closed.
4) Open top valve on sample bottle very slowly, filling steel line with fluid.
5) Set pressure exactly to the desired working pressure.
6) Read and record initial pump reading.
7) Open the cell valve and starting injection fluid until reach the desired volume, close the
cell valve.
8) Read and record final pump reading of charge.
9) Close sample bottle valves and disconnect the steel line.
10) Heat up oil sample to desired reservoir temperature.
PV Relation:

6. 1) Starting the test with pressure above the initial reservoir pressure.
2) After stabilization read and record the volume at first pressure.
3) Lower the pressure in even increments; agitate the cell until pressure equilibrium is
reached at the desired pressure level, then record the cell pressure and volume.
4) Repeat this procedure at successively lower pressure levels, recording cell pressure and
volume until surface pressure.
Flash Test:
1) After injection enough amount of sample to the cell.
2) Set the desired pressure and reservoir temperature.
3) Weight the empty flask and connect it in the top of cell valve.
4) Evacuated the gasometer and connected with the empty flask.
5) Open the cell valve and starting injection fluid slowly from the reservoir pressure to the
room pressure.
6) The gas released will go to the gasometer , recording the volume .
7) The oil will trap in the flask; weight the flask with full oil.
8) Calculate the density of oil in density meter.
9) Analysis the oil and gas composition by G.C.
Differential vaporization:
1) After injection enough amount of sample to the cell.
2) Set the desired pressure and reservoir temperature.
3) Set pressure exactly to the bubble point pressure.
4) Depending on bubble point divided the pressure to stages usually from 6 to 12 stage.
5) Lower pressure to the first stage.
6) Connect small trap with the gasometer to the top valve of cell.
7) Shaking well the cell until all the gas released from the oil at first stage.
8) Record the initial volume and open the cell valve very slowly until the all gas go out to
the gasometer.
9) Record the gas volume and the final remaining oil in the cell.
10) Analysis the gas composition.
11) Repeat this procedure until the last stage.

7. 12) At the last stage flashing the oil to the surface.
Separation test:
1) Clean and evacuate the separator cell.
2) Inject desired volume of sample to the separator cell at reservoir condition.
3) Set the desired pressure depending on separator stages (single or multi) and the separator
temperature.
4) Connect the gasometer to separator cell by cleaning and evacuated line.
5) Record the final oil volume after releasing gas at first stage.
6) Open the bottom separator valve to move all the gas to gasometer, record the volume.
7) If there more stages repeat the same procedure.
8) Weight empty flask and connected with the separator and gasometer.
9) Flashing the remaining oil to surface, weight the flask with oil.
Viscosity determination:
1) Clean and evacuate the rolling ball viscometer.
2) By injection pump, inject about 70 cc from the sample to viscometer.
3) Set the desired pressure which above the initial reservoir pressure and reservoir
temperature.
4) Agitate the viscometer until pressure equilibrium is reached at the desired pressure level.
5) Select the angle test and starting fall the ball from the top tube to the bottom, recording
the time of falling.
6) Repeat this step at all pressures from the first pressure to the 14.7 psia (above and below
bubble point pressure).
7) By knowing the density of oil and the density of ball and the time of falling the ball, we
calculate the viscosity at all stages.
5.1 Results:
 Direct Flash of Bottom Hole Sample to Atmospheric Conditions

8. At Pr = 3000 Psia and Tr = 204 Fo
GOR, Scf/STB Bo, bbl/STB Gas Gravity Oil Density, gm/cc APIo
93 1.0965 0.8374 0.8930 26.95
 PV relation
Bubble Point Pressure, Psia 660
 Constant Mass Expansion
Pressure, Psia Relative Volume, Vr/Vb Y-Function
3000 0.9769
2750 0.9795
2686 Pr 0.9803
2500 0.9821
2250 0.9835
2000 0.9852
1750 0.9875
1500 0.9900
1250 0.9925
1000 0.9950
800 0.9973
660 Pb 1.0000

9. 600 1.0329 3.04
500 1.1087 2.94
450 1.1613 2.89
400 1.2286 2.84
300 1.4375 2.74
200 1.8702 2.64
100 3.2021 2.54
85 3.6759 2.53
 Differential Liberation Test
P,Psia Rs RL Bo Den,gm/cc Den.,Ib/cf G.G Z factor Bg
3000 1.1175 0.8145 50.82
2750 1.1205 0.8123 50.69
2686 Pr 1.1214 0.8116 50.65
2500 1.1235 0.8101 50.55
2250 1.1251 0.8090 50.48
2000 1.1270 0.8076 50.39
1750 1.1297 0.8057 50.28
1500 1.1325 0.8037 50.15
1250 1.1354 0.8017 50.02

10. 1000 1.1382 0.7996 49.90
800 1.1409 0.7978 49.78
660 Pb 99 0 1.1440 0.7956 49.65
450 80 20 1.1314 0.8016 50.02 0.7693 0.9651 0.04029
300 63 36 1.1169 0.8093 50.50 0.8051 0.9734 0.06095
200 50 50 1.1043 0.8163 50.94 0.8371 0.9802 0.09206
100 31 68 1.0915 0.8225 51.33 0.9118 0.9888 0.18574
15 0 99 1.0754 0.8283 51.69 1.0250 0.9981 1.24992
 Separator Test
Stage Psep , Psia Tsep, Fo
GOR, Scf/STB Bo, bbl/STB
1 65 70 65 1.0710
2 30 45 24 0.9922
 Viscosity Test
Pressure, Psia Oil Viscosity, cp
3000 5.250

11. 2750 5.198
2686 Pr 5.184
2500 5.146
2250 5.104
2000 5.058
1750 5.028
1500 4.997
1250 4.975
1000 4.957
800 4.924
660 Pb 4.915
450 5.063
300 5.147
200 5.251
100 5.372
15 5.705
5.2 Part Two: Empirical Correlations
The most Empirical correlations used in this study are:

12. Property B.P.P. Bo Rs Viscosity
Correlations
Standing Standing Standing Beal
Vasquez &Beggs Vasquez &Beggs Vasquez &Beggs Beggs& Robinson
Glaso Glaso Al-Marhoun Glaso
Al-Marhoun Al-Marhoun Glaso Chew &Connally
Petrosky&Farshad Petrosky&Farshad Petrosky&Farshad Vasquez &Beggs
Dokla& Osman Material Balance Velarde
Mohsen Khazam Schmidt Hanafy
Valko&Mccain Arps De Ghetto
Omar&Todd
Al-shammasi
Macary&Elbatanoney
Mehran
 Bubble Point Pressure:
The Experimental Pb = 660Psia

13. The next table show the comparison and the absolute error percentage between the experimental
and the calculated Pb by using most of the Empirical correlations.
Correlation Experimental Pb Calculated Pb Abs. Error %
Standing 660 615 6.8
Glaso 660 596 10.7
Vesquez 660 609 7.7
Marhoun 660 746 11.5
Petrosky 660 632 4.4
Dokla 660 539 18.3
Mohsen Khazam 660 797 20.8
Valko&Mccain 660 631 4.4
Omar&Todd 660 702 6.3
Al-shammasi 660 667 1.1
Macary&Elbatanoney 660 806 22
Mehran
660 652 1.2
Table (5.1) Experimental and Calculated Pb
The figure 5.1 shows the absolute deviation percentage of calculated Pb with the experimental
one.

14.  Oil Formation Volume Factor:
The Experimental Bo = 1.0965 bbl/STB
The next table show the comparison and the absolute error percentage between the experimental
and the calculated Bo by using most of the Empirical correlations.
Correlation Experimental Bo Calculated Bo Abs. Error %
Standing 1.0965 1.1091 1.15
Glaso 1.0965 1.0802 1.5
Vesquez 1.0965 1.1189 2
Marhon 1.0965 1.1303 3
Experimental
Standing
Glaso
Vesquez
Al-marhoun
Petrosky
Dokla&Osman
Mohsen Khzam
Valko&Maccian
Omar&Todd
Al-shammasi
Macary&Elbatanoney
Mehran
0
200
400
600
800
1000
6.8 %
10.7 %
7.7%
11.5 %
4.4 % 18.3 %
20.8 %
4.4 %
6.3 % 1.1 %
22 %
1.2 %

15. Petrosky 1.0965 1.0961 0.03
Material Balance 1.0965 1.0190 7
Schmidt 1.0965 1.1273 2.8
Arps 1.0965 1.0965 0
Table (5.2) Experimental and Calculated Bo
The figure 5.2 shows the absolute deviation percentage of calculated Bo with the experimental
one.
LAB
Standing
Beggs
Glaso
Almarhoun
Petrosky
Material Balance
Schmidt
Arps
1.07
1.09
1.11
1.13 1.15 %
2 %
1.5 %
3 %
0.03 %
7 %
2.8 %
0 %

16.  Gas Oil Ratio:
The Experimental Rs = 93 Scf/STB
The next table show the comparison and the absolute error percentage between the experimental
and the calculated Rs by using most of the Empirical correlations.
Correlation Experimental Rs Calculated Rs Abs. Error %
Standing 93 529 469
Glaso 93 442 375
Vesquez 93 471 407
Marhon 93 558 500
Petrosky 93 475 411
Velarde 93 553 495
Hanafy 93 789 748
De Ghetto 93 213 129
Table (5.3) Experimental and Calculated Rs
The figure 5.3 shows the absolute deviation percentage of calculated Rs with the experimental
one.

17.  Oil Density:
The Experimental ρo = 0.8930 gm/cc, 55.723 Ib/cf
The next table show the comparison and the absolute error percentage between the experimental
and the calculatedρo by using most of the Empirical correlations.
Correlation Experimental ρo Calculated ρo Abs. Error %
Standing 55.723 51.015 8.45
Petrosky&Farshad 55.723 61.415 10.21
Vesquez&Beggs 55.723 51.006 8.47
Material Balance 55.723 51.785 7.07
Table (5.4) Experimental and Calculated ρo
The figure 5.4 shows the absolute deviation percentage of calculated ρo with the experimental
one.
Experimental
Standing
Glaso
Vesquez
Al-marhoun
Petrosky
Velarde
Hanafy
De Ghetto
0
100
200
300
400
500
600
700
800
469 %
375 %
407%
500 %
411 %
495 %
748 %
129 %

18.  Oil Viscosity:
Experimental dead oil viscosity =5.705cp
Experimental
Standing Vesquez&Beggs
Petrosky&Farshad
Material Balance
0
10
20
30
40
50
60
70
8.4 % 8.5 %
10.2 %
7 %

19. Experimental bubble point (saturated) oil viscosity = 4.915 cp
Experimental under saturated oil viscosity at reservoir P=2686 psia& T =204 F =5.184cp
To evaluate the Empirical correlations for estimating the oil viscosity we have to determine the
viscosityby correlations in three faces which are at dead oil, saturated oil, and under saturated oil
viscosity and compare them with the lab results.
Dead Oil Viscosity
Correlation Experimental µod Calculated µod Abs. Error %
Beal’s 5.705 3.334 41.5
Beggs 5.705 3.291 42.3
Glaso 5.705 3.793 33.5
Saturated Oil Viscosity
Correlation Experimental µob Calculated µob Abs. Error %
Chew 4.915 4.059 17.4
Beggs 4.915 3.129 36.3
Under-Saturated Oil Viscosity
Correlation Experimental µo Calculated µo Abs. Error %
Beggs 5.184 6.885 32.8
Table (5.5) Experimental and Calculated Oil Viscosites
The figure 5.5 shows the absolute deviation percentage of calculated viscosities with the
experimental one.

20. 5.3 Part Three: Equation of State
Simulation of PVT lab data by E.O.S (PVTisoftware):
Dead
Visc.
Beal's
Beegs
Glaso's
Saturated
Visc.
Chew
Beegs
Under-
Saturated
Visc.
Beegs
0
1
2
3
4
5
6
7
41.5 %
42.3 %
33.5 %
17.4 %
36.3 %
32.8 %

21. In this study, we use the PVTi software to simulate the Laboratory PVT data by using three
scenarios:
Scenario 1: the component up to C7+(with impurities N2, CO2, H2S)
Scenario 2: Grouping component up to C7+( N2–C1), (CO2-C2), (iC4-nC4), (iC5-nC5)
Scenario 3: all components up to C30+
We notes that the three scenarios need tuning
In this study, we choose three parameters for regression:
Regression 1: the change in binary interaction parameter (BIP)
Regression2: the change in omega a parameter (Ωa)
Regression3: the change in acentric factor parameter (ω)
Results:
5.3.1 All Scenarios before regression:
 Bubble point pressure, Original equations (before Regression):
Table (5.6)Pbbefore regression
Equation Pb lab C7+ ADD%
C7+ with
grouping
ADD% C30+ ADD%
PR3 660 403 39 361 45 375 43.2
SRK3 660 395 40 346 47.6 359 45.6
RK 660 267 59.5 246 62.7 252 61.8
ZJ 660 398 39.6 355 46 389 41
SW 660 403 39 361 45 375 43.2

22. Figure (5.6) Pbbefore regression
 Oil Formation Volume Factor, Original equations (before Regression):
Table (5.7) Bobefore regression
LAB PR3 SRK3 RK ZJ SW
0
100
200
300
400
500
600
700
Scenario1
Scenario2
Scenario3
39 %
45 %
43.2 %
40 %
47.6 %
45.6 %
59.5 %
62.7 %
61.8 %
39.6 %
46 %
41 %
39 %
45 %
43.2 %
Equation Bo lab C7+ ADD%
C7+ with
grouping
ADD% C30+ ADD%
PR3 1.0965 1.1151 1.7 1.1172 1.9 1.1622 6
SRK3 1.0965 1.1223 2.3 1.1242 2.5 1.1747 7.1
RK 1.0965 1.1791 7.5 1.1819 7.8 1.3758 25.4
ZJ 1.0965 1.1474 4.6 1.1493 4.8 1.2009 9.5
SW 1.0965 1.1181 1.9 1.1202 2.2 1.1571 5.5

23. Figure (5.7) Bobefore regression
 Gas Oil Ratio, Original equations (before Regression):
Table (5.8) Rsbefore regression
LAB PR3 SRK3 RK ZJ SW
0
0.2
0.4
0.6
0.8
1
1.2
1.4
Scenario1
Scenario2
Scenario3
1.7 %
1.9 %
6 %
2.3 %
2.5 %
7.1 %
7.5 %
7.8 %
25.4 %
4.6 %
4.8 %
9.5 %
1.9 %
2.2 %
5.5 %
Equation Rs lab C7+ ADD%
C7+ with
grouping
ADD% C30+ ADD%
PR3 93 81.9 12 81.7 12.2 82.2 11.6
SRK3 93 84.4 9.2 84.2 9.5 83.5 10.2
RK 93 74.3 20 74 20.4 72.5 22
ZJ 93 85.6 7.9 85.6 7.9 85.5 8
SW 93 82.3 11.5 82.1 11.7 77.6 16.5

24. Figure (5.8) Rsbefore regression
 Oil Density, Original equations (before Regression):
Table (5.9) ρobefore regression
LAB
PR3
SRK3
RK
ZJ
SW
0
20
40
60
80
100
Scenario1
Scenario2
Scenario3
12 %
12.2 %
11.6 %
9.2 %
9.5 %
10.2 %
20 %
20.4 %
22 %
7.9 %
7.9 %
8 %
11.5 %
11.7 %
16.5 %
Equation ρo lab C7+ ADD%
C7+ with
grouping
ADD% C30+ ADD%
PR3 0.8930 0.7779 13 0.7775 12.9 0.7785 12.8
SRK3 0.8930 0.7812 12.5 0.7809 12.6 0.7801 12.6
RK 0.8930 0.6400 28.3 0.6398 28.4 0.6025 32.5
ZJ 0.8930 0.7793 12.7 0.7792 12.7 0.7800 12.6
SW 0.8930 0.7817 12.4 0.7814 12.5 0.7347 17.7

25. Figure (5.9) ρobefore regression
 Oil Viscosities, Original equations (before Regression):
LAB
PR3
SRK3
RK
ZJ
SW
0
0.2
0.4
0.6
0.8
1
Scenario1
Scenario2
Scenario3
13 %
12.9 %
12.8 %
12.5 %
12.6%
12.6 %
28.3 %
28.4 %
32.5 %
12.7 %
12.7 %
12.6 %
11.4 %
12.5 %
17.7 %
Dead Oil Viscosity
Equation μod lab C7+ ADD%
C7+ with
grouping
ADD% C30+ ADD%
PR3 5.705 4.121 27.7 4.122 27.7 3.656 35.9
SRK3 5.705 3.834 32.7 3.833 32.8 3.322 41.7
RK 5.705 1.084 80.9 1.084 81 0.812 85.7
ZJ 5.705 3.420 40 3.423 40 3.284 42.4
SW 5.705 4.398 22.9 4.400 22.9 2.420 57.5

26. Table (5.10) Viscositiesbefore regression
Saturated Oil Viscosity
Equation μob lab C7+ ADD%
C7+ with
grouping
ADD% C30+ ADD%
PR3 4.915 3.674 25.3 3.667 25.3 3.192 35
SRK3 4.915 3.463 29.5 3.458 29.6 2.951 39.9
RK 4.915 1.072 78.2 1.071 78.2 0.833 83
ZJ 4.915 3.111 36.7 3.112 36.7 2.914 40.7
SW 4.915 3.829 22 3.822 22.2 2.204 55.1
Under-Saturated Viscosity
Equation μo lab C7+ ADD%
C7+ with
grouping
ADD% C30+ ADD%
PR3 5.184 4.583 11.6 4.574 11.8 4.074 21.4
SRK3 5.184 4.617 10.9 4.609 11 4.057 21.7
RK 5.184 1.326 74.4 1.325 74.4 1.002 80.6
ZJ 5.184 3.827 26.2 3.828 26.6 3.599 30.5
SW 5.184 4.693 9.5 4.683 9.7 2.632 49.2

27. Figure (5.10) Viscositiesbefore regression
LAB PR3 SRK3 RK ZJ SW
0
1
2
3
4
5
6
Under-Sat.
Sat. Oil
Dead Oil
11.6 %
25.25%
27.7%
10.9 %
29.5%
32.7 % 74.4 %
78.2 %
80.9 %
26.17 %
36.7%
40 %
9.5 %
22 %
22.9 %

28. 5.3.2 After Regression:
Next tables show every property with three regressions for all scenarios:
Regression 1, the change in Binary Interaction Parameter (BIP)
Regression 2,the change in Omega a Parameter (Ωa)
Regression 3, the change in Acentric Factor Parameter (ω)
 Bubble point pressure, (After Regression1):
Table (5.11) Pb After regression 1
 Bubble point pressure, (After Regression2):
Equation Pb lab C7+ ADD%
C7+ with
grouping
ADD% C30+ ADD%
PR3 660 551 16.5 522 21 380 42.4
SRK3 660 657 0.45 610 7.5 426 35.5
RK 660 403 39 387 41.4 278 57.9
ZJ 660 660 0 654 0.9 453 31.4
SW 660 551 16.5 522 21 380 42.4

29. Table (5.12) Pb After regression 2
 Bubble point pressure, (After Regression3):
Table (5.13) Pb After regression 3
Equation Pb lab C7+ ADD%
C7+ with
grouping
ADD% C30+ ADD%
PR3 660 660 0 235 3.8 382 42.12
SRK3 660 660.18 0.02 660.07 0 428 35.15
RK 660 478 27.5 424 35.7 278 57.88
ZJ 660 660.3 0.04 660.02 0 454 31.21
SW 660
Equation Pb lab C7+ ADD%
C7+ with
grouping
ADD% C30+ ADD%
PR3 660 473 28 419 36.5 379 42.6
SRK3 660 550 17 467 29.2 425 35.6
RK 660 294 55.5 268 59.4 275 58.3
ZJ 660 452 31.5 401 39.2 447 32.3
SW 660 473 28.3 419 36.5 379 42.6

30. LAB PR3 SRK3 RK ZJ SW
0
200
400
600
800
BIP
Omega a
Acentric Factor
16.5%
0 %
28 %
0.45 %
0.02 %
17 %
27.5%
7.8 %
55.5 %
0 %
0.04 %
31.5 %
16.5 %
28.3 %
LAB PR3 SRK3 RK ZJ SW
0
100
200
300
400
500
600
700
BIP
Omega a
Acentric Factor
3.8%
21 %
36.5 %
7.5%
0%
29.2 %
41.4 %
35.7%
59.4%
0.9 %
0 %
39.3 %
21 %
36.5 %
Figure (5.11) Pb After regression 1
Figure (5.12) Pb After regression 2

31. LAB
PR3
SRK3
RK
ZJ
SW
0
100
200
300
400
500
600
700
BIP
Omega a
Acentric Factor
42.4 %
42.12 %
42.6 %
35.5 %
35.25%
35.6%
57.9 %
57.88 %
58.3%
31.4 %
31.21 %
32.3%
42.4 %
42.6 %
Figure (5.13) Pb After regression 3
 Oil Formation Volume Factor, (After Regression1):
Table (5.14) Bo After regression 1
Equation Bo lab C7+ ADD%
C7+ with
grouping
ADD% C30+ ADD%
PR3 1.0965 1.1129 1.5 1.1149 1.7 1.1619 6
SRK3 1.0965 1.0773 1.75 1.0787 1.6 1.0869 0.87
RK 1.0965 1.0929 0.3 1.0944 0.2 1.1171 1.87
ZJ 1.0965 1.1074 0.99 1.1087 1.1 1.1117 1.38
SW 1.0965 1.1159 1.77 1.1179 2 1.1569 5.51

32.  Oil Formation Volume Factor, (After Regression2):
Table (5.15) Bo After regression 2
 Oil Formation Volume Factor, (After Regression3):
Table (5.16) Bo After regression 3
Equation Bo lab C7+ ADD%
C7+ with
grouping
ADD% C30+ ADD%
PR3 1.0965 1.1067 0.9 1.1100 1.23 1.1617 5.9
SRK3 1.0965 1.0738 2 1.0753 1.93 1.0867 0.9
RK 1.0965 1.0833 1.2 1.0851 1.04 1.1168 1.85
ZJ 1.0965 1.1058 0.85 1.1083 1.07 1.1116 1.4
SW 1.0965
Equation Bo lab C7+ ADD%
C7+ with
grouping
ADD% C30+ ADD%
PR3 1.0965 1.1112 1.3 1.1132 1.52 1.1620 5.97
SRK3 1.0965 1.0781 1.68 1.0796 1.54 1.0869 0.88
RK 1.0965 1.0965 0 1.0984 0.17 1.1174 1.91
ZJ 1.0965 1.1096 1.2 1.1112 1.34 1.1119 1.4
SW 1.0965 1.1196 2.1 1.1218 2.3 1.1576 5.57

33. LAB PR3 SRK3 RK ZJ SW
0
0.2
0.4
0.6
0.8
1
BIP
Omega a
Acentric Factor
1.5%
0.9 %
1.3 %
1.75%
2 %
1.68 %
0.3%
1.2 %
0 %
0.85%
0.99 %
1.2 %
1.77 %
2.1 %
Figure (5.14) Bo After regression 1
Figure (5.15) Bo After regression 2
LAB PR3 SRK3 RK ZJ SW
0
0.2
0.4
0.6
0.8
1
BIP
Acenric Fator
Omega a
1.7%
1.23 %
1.52 %
1.6%
1.93%
1.54 %
0.2 %
0.17%
1.04%
1.1 %
1.07 %
1.34 %
2 %
2.3 %

34. LAB
PR3
SRK3
RK
ZJ
SW
0
0.2
0.4
0.6
0.8
1
BIP
Omega a
Acentric Factor
6 %
5.9 %
5.97%
0.87 %
0.9%
0.88%
1.87%
1.85 %
1.91%
1.38 %
1.4 %
1.4%
5.51 %
5.57%
Figure (5.16) Bo After regression 3
 Gas Oil Ratio, (After Regression1):
Table (5.17) Rs After regression 1
 Gas Oil Ratio, (After Regression2):
Equation Rs lab C7+ ADD%
C7+ with
grouping
ADD% C30+ ADD%
PR3 93 83.2 10.5 83.2 10.5 82.3 11.5
SRK3 93 74.4 20 73.9 20.5 72.5 22
RK 93 70.5 24 69.9 24.9 65.2 29.9
ZJ 93 83.5 10.2 83.1 10.6 82.1 11.7
SW 93 83.6 10.1 83.6 10.1 77.7 16.5

35. Table (5.18) Rs After regression 2
 Gas Oil Ratio, (After Regression3):
Table (5.19) Rs After regression 3
Equation Rs lab C7+ ADD%
C7+ with
grouping
ADD% C30+ ADD%
PR3 93 89.3 4 92.2 0.86 82.5 11.3
SRK3 93 76 18 78 16 72.6 21.9
RK 93 75.5 19 75.1 19.2 65.3 29.8
ZJ 93 87.9 5.5 90.4 2.8 82.2 11.6
SW 93
Equation Rs lab C7+ ADD%
C7+ with
grouping
ADD% C30+ ADD%
PR3 93 84.2 9.5 84.2 9.5 82.4 11.4
SRK3 93 74.7 19.7 74.2 20.2 72.5 22
RK 93 68.7 26.1 67.9 27 65.1 30
ZJ 93 82 12 81.4 12.5 82 11.8
SW 93 91.5 1.6 91.5 1.6 78.2 16

36. Figure (5.17) Rs After regression 1
Figure (5.18) Rs After regression 2
LAB PR3 SRK3 RK ZJ SW
0
20
40
60
80
100
BIP
Omega a
Acentric Factor
10.5
4 %
9.5%
20 %
13 %
19.7 %
24 %
19 %
26.1%
10.2 %
5.5 %
12 %
10.1 %
1.6 %
LAB
PR3
SRK3
RK
ZJ
SW
0
20
40
60
80
100
BIP
Omega a
Acentric Factor
10.5 %
0.86 %
9.5%
20.5 %
16 %
20.2 %
24.9%
19.2 %
27 %
10.6 %
2.8 %
12.5 %
10.1%
1.6%

37. Figure (5.19) Rs After regression 3
 Oil Density, (After Regression1):
Table (5.20) ρo After regression 1
LAB
PR3
SRK3
RK
ZJ
SW
0
20
40
60
80
100
BIP
Omega a
Acentric Factor
11.5 %
11.3 %
11.4 %
22 %
21.9 %
22 %
29.9 %
29.8%
30 %
11.7 %
11.6 %
11.8 %
16.5 %
16 %
Equation ρo lab C7+ ADD%
C7+ with
grouping
ADD% C30+ ADD%
PR3 0.8930 0.7781 12.8 0.7778 13 0.7785 12.8
SRK3 0.8930 0.7918 11.33 0.7914 11.3 0.7923 11.3
RK 0.8930 0.7319 18 0.7316 18 0.6910 22.6
ZJ 0.8930 0.8839 1 0.8837 1 0.8861 0.77
SW 0.8930 0.7819 12.4 0.7816 12.5 0.7347 17.7

38.  Oil Density, (After Regression2):
Table (5.21) ρo After regression 2
 Oil Density, (After Regression3):
Table (5.22) ρo After regression 3
Equation ρo lab C7+ ADD%
C7+ with
grouping
ADD% C30+ ADD%
PR3 0.8930 0.7819 12.4 0.7824 12.4 0.7797 12.7
SRK3 0.8930 0.7938 11.10 0.7944 11 0.7932 11.2
RK 0.8930 0.7632 14.5 0.7629 14.6 0.6921 22.5
ZJ 0.8930 0.9019 0.99 0.9069 1.6 0.8871 0.66
SW 0.8930
Equation ρo lab C7+ ADD%
C7+ with
grouping
ADD% C30+ ADD%
PR3 0.8930 0.7796 12.7 0.7793 12.7 0.7793 12.7
SRK3 0.8930 0.7930 11.2 0.7926 11.2 0.7929 11.2
RK 0.8930 0.7317 18 0.7313 18.1 0.6910 22.6
ZJ 0.8930 0.8837 1 0.8834 1.07 0.8861 0.77
SW 0.8930 0.8477 5 0.8473 5.12 0.7392 17.2

39. Figure (5.20) ρo After regression 1
Figure (5.21) ρo After regression 2
LAB PR3 SRK3 RK ZJ SW
0
0.2
0.4
0.6
0.8
1
BIP
Omega a
Acentric Factor
12.8%
12.4 %
12.7 %
11.33%
11.1 %
11.2%
18%
14.5 %
18 %
1%
0.99 %
1 %
12.4 %
5%
LAB PR3 SRK3 RK ZJ SW
0
0.2
0.4
0.6
0.8
1
BIP
Omega a
Acentric Factor
13%
12.4 %
12.7 %
11.3%
11%
11.2 %
18 %
14.6%
18.1%
1 %
16 %
1.07 %
12.5 %
5.12 %

40. Figure (5.22) ρo After regression 3
 Oil Viscosities, (After Regression1):
LAB
PR3 SRK3
RK
ZJ SW
0
0.2
0.4
0.6
0.8
1
BIP
Omega a
Acentric Factor
12.8 %
12.7 %
12.7%
11.3 %
11.2%
11.2%
22.6%
22.5%
22.5%
0.77 %
1.4 %
0.77%
17.7 %
17.2%
Dead Oil Viscosity
Equation μod lab C7+ ADD%
C7+ with
grouping
ADD% C30+ ADD%
PR3 5.705 4.109 27.9 4.109 27.9 3.655 35.9
SRK3 5.705 5.022 11.9 5.012 12.1 4.336 24
RK 5.705 2.458 56.9 2.456 57 1.560 72.6
ZJ 5.705 13.219 132 13.229 132 12.311 115
SW 5.705 4.384 23.1 4.384 23.1 2.420 57.5
Saturated Oil Viscosity

41. Table (5.23) Viscosity After regression 1
 Oil Viscosities, (After Regression2):
Equation μob lab C7+ ADD%
C7+ with
grouping
ADD% C30+ ADD%
PR3 4.915 3.652 25.7 3.643 25.9 3.191 35
SRK3 4.915 4.815 2 4.807 2.2 4.174 15
RK 4.915 2.382 51.5 2.379 51.5 1.564 68.2
ZJ 4.915 11.893 142 11.890 142 11.051 124
SW 4.915 3.807 22.5 3.798 22.7 2.203 55.2
Under-Saturated Viscosity
Equation μo lab C7+ ADD%
C7+ with
grouping
ADD% C30+ ADD%
PR3 5.184 4.562 11.9 4.551 12.2 4.073 21.4
SRK3 5.184 5.742 10.7 5.731 10.6 5.066 2.28
RK 5.184 2.959 42.9 2.956 43 1.885 63.64
ZJ 5.184 14.289 175 14.288 174.5 13.295 156
SW 5.184 4.673 9.8 4.661 10 2.631 49.2

42. Dead Oil Viscosity
Equation μod lab C7+ ADD%
C7+ with
grouping
ADD% C30+ ADD%
PR3 5.705 5.275 7.5 5.466 4.2 3.744 34.37
SRK3 5.705 5.838 2.3 6.151 8 4.422 22.5
RK 5.705 4.167 27 4.166 27 1.582 72.26
ZJ 5.705 19.710 245 22.090 287 12.578 120
SW 5.705
Saturated Oil Viscosity
Equation μob lab C7+ ADD%
C7+ with
grouping
ADD% C30+ ADD%
PR3 4.915 4.737 3.62 4.905 0.2 3.262 33.63
SRK3 4.915 5.684 15.65 6.040 23 4.257 13.38
RK 4.915 3.981 19 3.977 19 1.585 67.75
ZJ 4.915 17.730 260 19.840 304 11.287 130
SW 4.915
Under-Saturated Viscosity
Equation μo lab C7+ ADD%
C7+ with
grouping
ADD% C30+ ADD%
PR3 5.184 5.275 1.75 5.392 4 4.137 20.19
SRK3 5.184 6.342 22.3 6.599 27.3 5.141 0.83
RK 5.184 4.452 14.12 4.448 14.2 1.904 63.27

43. Table (5.24) Viscosity After regression 2
 Oil Viscosities, (After Regression3):
ZJ 5.184 19.927 284 21.946 323 13.526 161
SW 5.184
Dead Oil Viscosity
Equation μod lab C7+ ADD%
C7+ with
grouping
ADD% C30+ ADD%
PR3 5.705 4.448 22 4.448 22 3.711 34.9
SRK3 5.705 5.350 6.2 5.340 6.4 4.384 23.2
RK 5.705 2.462 57 2.460 56.9 1.560 72.6
ZJ 5.705 13.26 132.4 13.276 133 12.312 116
SW 5.705 11.043 93.6 11.095 94.5 2.548 55.3
Saturated Oil Viscosity
Equation μob lab C7+ ADD%
C7+ with
grouping
ADD% C30+ ADD%
PR3 4.915 3.981 19 3.974 19.1 3.236 34.2
SRK3 4.915 5.183 5.5 5.175 5.29 4.221 14.1
RK 4.915 2.395 51.2 2.393 51.3 1.564 68.2
ZJ 4.915 11.96 143.3 11.976 143 11.053 125
SW 4.915 8.772 78.5 8.749 78 2.304 53.1

44. Table (5.25) Viscosity After regression 3
Figure (5.23) Viscosity After regression 1
LAB PR3 SRK3 RK ZJ SW
0
2
4
6
8
10
12
14
16
Under-Sat.
Sat. Oil
Dead Oil
11.9 %
25.7%
27.9%
10.7 %
2%
11.9 %
42.9 %
51.5 %
56.9 %
175 %
142 %
132 %
9.8%
22.5 %
23.1 %
Under-Saturated Viscosity
Equation μo lab C7+ ADD%
C7+ with
grouping
ADD% C30+ ADD%
PR3 5.184 4.716 9 4.706 9.2 4.113 20.7
SRK3 5.184 5.939 14.6 5.930 14.4 5.108 1.5
RK 5.184 2.972 42.7 2.970 42.7 1.885 63.6
ZJ 5.184 14.36 177 14.373 177 13.298 157
SW 5.184 10.45 101.5 10.423 101 2.747 47

45. Figure (5.24) Viscosity After regression 2
Figure (5.25) Viscosity After regression 3
5.4 Part Four: New Correlations for Libyan oil
LAB PR3 SRK3 RK ZJ
0
5
10
15
20
Under-Sat.
Sat. Oil
Dead Oil
1.75 %
3.62%
7.5%
22.3 %
15.65%
2.3 %
14.12 %
19%
27 %
284 %
260 %
245 %
LAB PR3 SRK3 RK ZJ SW
0
2
4
6
8
10
12
14
16
Under-Sat
Sat. Oil
Dead Oil
9 %
19%
22%
14.6 %
5.5%
6.2 %
42.7 %
51.2%
57 %
177 %
143 %
132 %
102 %
78 %
93.6 %

46. In last part of this study, we have tried to develop new correlations for Libyan crude oil to
estimate the following properties by using regression analysis by DataFit software.
 Bubble Point Pressure, Pb
Experimental PVT data were collected from different reservoirs in the Sirte basin area.
Correlations Development
 Bubble Point Pressure, Pb
The bubble point pressure is function of (Rs,ɣg, API, T) so that the regression analysis will be
according to these parameters.
The data were used in DataFit software is shown in Table (5.26).
Rs,
Scf/STB
ɣg API T, F Exp. Pb Cal. Pb Error%
93 0.8374 26.95 204 660 1020 -54.58
188 0.9347 33.9 117 655 604 7.71
535 1.074 38.8 234 1892 1670 11.72
1382 0.9808 36.51 184 3317 3333 -0.48
1366 0.9534 37.41 184 3255 3290 -1.07
1155 0.9531 38.86 172 2716 2754 -1.41
755 1.0012 39.87 170 2120 1854 12.57
88 1.0979 36.91 143 335 355 -6.01
133 0.9236 42.33 186 505 590 -16.87
368 0.9447 35.25 235 1865 1476 20.86
521 1.5472 48.66 192 944 971 -2.87
39 1.07 34.76 188 180 523 -190.45
56 1.1769 34.13 127 145 248 -71.10
245 1.407 39.85 145 535 470 12.12
320 0.9319 35.4 235 1705 1377 19.23
104 1.108 35.58 145 498 427 14.30
475 1.0482 38.1 239 1920 1597 16.84

47. 314 1.2369 50.07 239 740 861 -16.39
1139 0.9343 43.91 300 2930 3178 -8.45
127 1.1242 32.6 195 600 768 -28.07
695 1.085 40.45 201 1700 1811 -6.55
851 1.0359 34.68 216 2570 2378 7.46
1323 0.97 40.02 263 3250 3480 -7.09
Table (5.26)
All the Fit information is attached in appendix B.
The Equation ID from the regression analysis is: a*x1+b*x2+c*x3+d*x4+e
Where, the Model Definition will be:
Pb = a*Rs+ b*ɣg + c*API + d*T + e
Where:
a = 2.1068 b = -485.0232 c = -25.4528 d = 4.5037 e = 997.6735
The R^2
= 0.9626 (96.26 %)

48. Figure (5.26) Experimental Pb Vs New correlation Pb
The range data of new correlations:
Pb is function of ( Rs, API, s.g, and T)
Property Rs, Scf/STB ɣg API T, F
Minimum 93 0.8374 26.95 117
Maximum 1382 1.2369 50.07 300
0
500
1000
1500
2000
2500
3000
3500
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
Experimental Pb Data New Correlation Pb Data

49. Conclusions:
Based on the results of this study, the following conclusions are obtained:
 Complete PVT lab studies have been done for one Libyan oil sample to compare the
properties with the Empirical correlations for Middle East crude oil and the results show
that there is a clear difference.
 The quality of the data is of vital importance for a reasonable tuning effort.
 Average absolute error is an important indicator of the accuracy of an empirical model; it
is used in this study as a comparative criterion for testing the accuracy of correlations.
 Empirical correlations for Middle East crude oil have been compared for bubble point
pressure, the solution gas-oil-ratio, oil formation volume factor, oil density, and oil
viscosity.
 The PVT correlations can be placed in the following order with respect to their accuracy:
 For bubble point pressure, some correlations gives good result like Al-shammasi,
Mehran, and Petrosky&Farashad while others gives high percentage of error like
Dokla&Osman and Al Marhoun.
 For oil formation volume factor, all the correlations gives acceptable results
accept the Material balance give about 7% Average error.
 For solution gas oil ratio, in our case which heavy oil all the correlations gives
high percentage of error.
 For oil density, the four correlations give results near to each other were the
percentage of error between 7-10%.
 For oil viscosity, this property is a critical one and there is no correlation gives
good much, so the correlations not reliable to use.
 Characterization the experimental data by PVTi software show that:
 When we use the original Equation of State to predict the previous PVT
properties, we have got unsatisfactory results.
 All the E.O.S needs tuning.
 In three scenarios that used in this study, the best one is the component up to C7+
without grouping.

50.  After regression we found that:
 We have got the good match with lab results.
 The bubble point pressure is very sensitive to the omega A.
 There is a clear difference between the three scenarios where is the best results
that obtain from C7+ without grouping while the last one which up to C30+ gives
less accurate results.
 The best EOS are 3parameter Peng_Robinson (PR3) and 3parameter
Soave_Redlich_Kwong (SRK3), while Radlich_Kowng (RK) proved to be the
worst one.
 For oil viscosity the ZJ correlation gives high percentage of error so it’s not
advised to use.
 The new correlations for bubble point pressure and oil formation volume factor give good
results and can be used with Libyan crude oil in the same area.
Recommendations:
The main recommendations we can get from this study are:
 Before using the Empirical correlations in reservoir calculations, we must make sure that
they can be used for estimating the same PVT parameters for all types of oil and gas
mixture with properties falling within the range of data for each correlation.
 To be more accurate we should compare the results that obtained from the correlations
with the data of the experimental work in PVT lab.
 With Libyan crude oil we advice to modify a new correlations that special for Libyan oil
like Mohsen Khazam.
 When use any simulator to get PVT properties, we have to choose the best scenario that
give the best result.
 About the new correlations for Libyan crude oil we use just 23 samples which not enough
so that this work should be continue with more samples in the same area.

51. References:
1. Danesh, A. (1998) ‘PVT and Phase Behavior of Petroleum Reservoir Fluids’, First Edition,
Amsterdam, Elsevier Science B.V.
2. Tarek, A. (2001) ‘Reservoir Engineering’ Hand Book, Second Edition, GPP.
3. McCain, W. D. (1990) ‘The Properties of Petroleum Fluids’, Second Edition, Tulsa, OK, USA:
Pennwell Books.
4. Ahmed, T. (1989) ‘Hydrocarbon Phase Behavior’, Gulf Publishing Company, Houston, Texas,
Volume 7.
5. AL-Marhoun, M. A. (1988) ‘PVT Correlations for Middle East Crude Oils’, JPT, Volume 40,
Number 5, P.P 650-666.
6. Hemmati, M. N. & Kharrat, R. (2007) ‘Evaluation of Empirically Derived PVT Properties for
Middle East Crude Oils’, Scientia Iranica, Volume 14, Number 4, P.P 358-368.
7. Chew, J. & Connally, C. A. (1959) ‘A Viscosity Correlation for Gas-Saturated Crude Oils’,
Trans. AIME, Volume 216, P.P 23-25.
8. Burcik, E. J. (1979) ‘Properties of Petroleum Reservoir Fluids’, USA, International Human
Resources Development Corporation.
9. Dokla, M. F. & Osman, M. E. (1992) ‘Correlation of PVT Properties for UAE Cruds’ SPE, P.P
80-81.
10. Khazme, M.: "Statistical Evaluation and Optimization of PVT Correlations For Libyan Crud
Oils"
11. Ayala, L. F. (2006) ‘Phase Behavior of Hydrocarbon Fluids – The Key to Understanding Oil and
Gas Engineering Systems’, Business Briefing: Oil & Gas Processing Review, P.P 16-18.
12. Glaso, O. (1980) ‘Generalized Pressure-Volume-Temperature Correlations’, JPT, P.P 785-795.
13. Vasquez, M. & Beggs, D. (1980) ‘Correlations for Fluid Physical Properties Prediction’, JPT,
P.P 968-970.

52. 14. Beggs, H. D. & Robinson, J. R. (1975) ‘Estimating the Viscosity of Crude Oil Systems’, JPT,
P.P 1140-1141.
15. Petrosky, G. E. & Farshad F. F. (1990) ‘Pressure-Volume-Temperature Correlations For Gulf of
Mexico Crud Oils’, SPE Paper No.26644, SPE 68th Annual Technical Conference and
Exhibition, Houston.
16. Valkó, P.P, and McCain, W.D. Jr.: "Reservoir Oil Bubble Point Pressures revisited; solution gas-
oil ratios and surface gas specific gravities," J. Pet. Sci. Eng. (2003) 153-169.
17. Macary, S.M. and M. H. EL-Batanoney.: "Derivation of PVT Correlations for the Gulf of Suez
Crud Oils" EGPC 11th, Petroleum Exploration / Production Conference.
18. Beal, C. (1946) ‘The Viscosity of Air, Water, Natural Gas, Crude Oils and Associated Gases at
Oil Field Temperature and Pressures’, Trans. AIME, Volume 165, P.P 94-112.
19. PVTi Software Technical Description file.
Thanks for Attention