Archives of Petroleum & Environmental Biotechnology (ISSN: 2574-7614)

Article / research article

"Effect of Non-hydrocarbon components on Gas Compressibility Factor Values and Correlations"

Ghareb M Hamada*

 Petroleum Engineering Department, Faculty of Geosciences and Petroleum Engineering, Universiti Technologi Petronas

*Corresponding author: Ghareb M. Hamada, Petroleum Engineering Department, Faculty of Geosciences and Petroleum Engineering, Universiti Technologi Petronas, Malaysia, E-mail: ghareb.mostafa@utp.edu.my

Received Date: 29 October, 2016; Accepted Date: 29 October, 2016; Published Date:29 October, 2016

Gas compressibility factor is necessary in most natural gas engineering calculations. The most common sources of z-factor values are experimental measurements, equation of state and empirical correlations. There are more than twenty correlations available with two variables for calculating the z-factor from fitting Standing-Katz chart values in EOS or through fitting technique. The theory of corresponding states dictates that the Z-factor can be uniquely defined as function of reduced pressure and temperature. Natural gases frequently contain material other than hydrocarbon components, such as nitrogen, carbon dioxide and hydrogen sulfide. Hydrocarbon gases are classified as sweet or sour depending on the hydrogen sulfide content. Both sweet and sour gases may contain nitrogen, carbon dioxide or both. The compositions of most natural gases are hydrocarbon of the same family (paraffin hydrocarbons), so the correlation of this type is possible but containing non-hydrocarbon on the gases, make the prediction difficult. This paper focuses on evaluating the correlations which calculate gas compressibility factor for natural gas reservoirs contains non-hydrocarbon components. It is found that gas pseudo-critical temperature decreases with the increase of N2 and H2S. Also, it is observed that in the tested gas reservoirs which contain C7+ by Stewart Mixing Rules and Kay’s there are some deviation on z factor between two methods that became negligible by using the correction method for non-hydrocarbon.

Introduction

Gas compressibility factor is involved in calculating gas properties such as formation volume factor, density, compressibility and viscosity. All these properties are necessary in the oil and gas industry for evaluating newly discovered gas reservoirs, calculating initial gas reserves, predicting future gas production and designing production tubing and pipelines. The accurate measurement of natural gas related fluids is difficult. The compressibility factor is a ubiquitous concept in measurement. It arises in many industry practices and standard. The industry standard is to measure gas properties, pressure-volume-temperature in the laboratory using reservoir samples. The drawback is that these isothermally measured PVT data is applicable at measures pressure and reservoir temperature. Calculation Methods such as correlations and equation of state are used to predict properties at other pressure and temperature. Also, laboratory analyses for PVT behavior are sometimes expensive and time consuming. Correlations, which are used to predict gas compressibility factor, are much easier and faster than equation of state. Natural gases frequently contain material other than hydrocarbon components, such as nitrogen, carbon dioxide and hydrogen sulfide. Hydrocarbon gases are classified as sweet or sour depending on the hydrogen sulfide content. Both sweet and sour gases may contain nitrogen, carbon dioxide or both. Sometimes these correlations have comparable accuracy to equation of state. Predicting compressibility factor for gas containing non-hydrocarbon (impurities) is much difficult than that for sweet gas. The compositions of most natural gases are hydrocarbon of the same family (paraffin hydrocarbons), so the correlation of this type is possible but containing non-hydrocarbon on the gases, make the prediction difficult. Therefore, several attempts have been made to predict compressibility factor for sweet gases, Wichert and Aziz and Carr-Kobayashi-Burrows presented correction for the presences of hydrogen sulfide and carbon dioxide for determining the compressibility factor. The objective of this study is evaluating the pervious correlations which calculate gas compressibility factor for gases contain non-hydrocarbon component and observe the effect of these component on Z factor.

 

Correlation

The most common method is to use one of the forms of the principle of corresponding states. In this form, gas compressibility factor is expressed as function of pseudo-reduced pressure and temperature (Ppr,Tpr). Compressibility factors are function of composition as well as temperature and pressure. Standing and Katz (SK) presented a chart for determining gas compressibility factor based on the principle of corresponding states. The SK chart was prepared for binary mixture of low molecular weight sweet gases. Several mathematical expressions fitting the SK chart have been proposed to calculate the gas compressibility factor. Dranchuk- Abou- Kassem (DK) correlation is the most accurate representation of SK chart. When dealing with gas mixture, the gas mixture is critical pressure (Ppc) and temperature (Tpc) are required. Critical properties of natural gas are calculated from either gas composition or gas gravity. Several Mixing rules have been proposed to calculate mixture critical properties of natural gases. Among these methods, Kay’s mixing rule and stewart-Burkhardt-Voo (SBV) are the most widely used. Kay’s mixing rule is simple and provides an accurate determination of gas compressibility factor for sweet gases of low molecular weight. Satter and Campbell evaluated several mixing rules for calculating properties of natural gases. They concluded that Stewart-Burkhardt-Voo rule known as SBV provided the most satisfactory results especially for gases of high molecular weight. Sutton studied the performance of several mixing rule for calculating compressibility factor for gas condensates that contain a large amount of heptanes plus fraction. Sutton modified SBV mixing rule to account for the presence of heptanes plus in the natural gases. Standard laboratory analysis gives composition of natural gases through hexane and lump components heavier than hexane in heptane plus fraction known as C7+ critical properties of pure components are well documents as shown table (1).

The critical properties of the C7+, fraction are calculated from correlations using molecular weight and specific gravity of the heptanes plus. Standing presented correlation of pseudo critical properties to gas gravity based on low molecular weight which are:

The previous correlation work only when there no non-hydrocarbon gases present on the gases. Sutton developed the following correlation work with high molecular weight of gases.

 

The gases which Suttton used to develop previous correlation were sweet gases with minor amount of carbon dioxide and nitrogen and no hydrogen sulfide. Then, Elsharkawy et al. developed Sutton correlation but will cover heavier hydrocarbons and minor of hydrogen sulfide.

 

3.1 Methods of Calculating the Pseudo-Critical Gas Properties   

The pseudo-critical properties provide a mean to correlate the physical properties of mixtures with principle of the corresponding states. The principle of corresponding states suggests that pure but similar gases have the same gas deviation or Z factor at the same values of reduced pressure and temperature. The mixture of chemically similar gases can be correlated with reduced temperature and reduced pressure.

There are several methods which are:

  1. Mixing Rules developed by Stewart et al and Kay’s requires the gas composition to be known.
  2. Estimating pseudo-critical properties when the gas composition is not known, developed by Sutton.

The theory corresponding states dictates that the Z-factor can be uniquely defined as function of reduced pressure and temperature. The reduce pressure and temperatures are:

The values of pseudo-critical pressure and temperature can be estimated from the following equations if the composition of the gas and the critical properties of the individual component are Known ( kay):

3.1.1 Procedures for Stewart et al. Mixing Rules

  1. Estimate the boiling temperature of the C7+ fraction

                                                                                                  

     2. Estimate the pseudo-critical pressure of the C7+ fraction.

         

       3.Estimate the pseudo-critical temperature of the C7+ fraction.

                

        4. Determine the correction factor Fj,ξj and ξk for high- molecular weight component using Sutton’s method

                       

        5. Obtain the critical pressure and temperature of the remaining component from table (1).

        6. Determine the pseudo-critical pressure and temperature of the gas

        7. Calculate the parameters J and K

        8. Correct the parameters J and K for the C7+ fraction

         

        9. Calculate the pseudo-critical temperature and pressure

                 

        10. Calculated the Pseudo-reduced pressure and temperature by using equation 7

        11. Finding z factor from Standing & Katz compressibility factors figure 1

3.1.2 Procedures for Sutton’s correlations of sweet gas

  1. Estimate the gas gravity of the mixture
  2. Calculate the pseudo-critical pressure and temperature for the hydrocarbon component by using the following equation: 

                                                                                                        

       3. Ignore the nitrogen contamination, then 

                                                                               

       4. Calculated the Pseudo-reduced pressure and temperature from equation 7

       5. Finding z factor from Standing & Katz compressibility factors chart

3.1.3 Procedures for Sutton’s correlations of Sour gas

  1. Determine the gravity of the hydrocarbon components of the Mixture

             

     2. Calculate the pseudo-critical pressure and temperature for the hydrocarbon component by using the following equations.

                

       3. Calculate the Pesudo-critical properties of the total mixture

            

3.2 Methods of Correction the Pseudo-Critical Gas Properties for H2S and CO2 contamination.

Natural gases, which contain H2S and CO2 frequently, exhibit different compressibility factor behavior than do sweet gases. Wichert and Aziz developed a simple, easy to use calculation procedure to account for these differences.

3.2.1 Wichert-Aziz Correction Method

This method permits the use of the standing-Katz chart, by using a pseudo-critical temperature adjustment factor, which is function of the concentration of CO2 and H2S in the sour gas. The following Wichert and Aziz correlation is also can obtain from figure 2:

                                                                                  

Wherehere the pseudo-critical temperature, T’pc and pressure P’pc, adjusted for CO2 and H2S contamination are:

                                                                                                    

Where,

A: Sum of the mole fractions of H2S and CO2 in the gas mixture

B: Mole fraction of H2S in the gas mixture.

3.3 Methods of Correction the Pseudo-Critical Gas Properties for N2 and H2O vapor contamination

Carr-Kobayashi and Burrows developed a simple procedure to adjust the pseudo-critical properties of natural gases when non-hydrocarbon components are present.

3.3.1 Carr-Kobayashi and Burrows Correction Method

The procedures to obtain the correction are following:

Known the specific gravity of the natural gas, calculate the pseudo-critical temperature and pressure from .

 

  1. or by the following equation:

            

        2. Calculate the corrections for nitrogen and water vapor.

                                                                                                       

        3. Calculate the pseudo-critical temperature and pressure for nitrogen and water vapor.

                                                 

      4. If there is no H2S or CO2 in the gas mixture, then T’p=Tpc and P’pc=Ppc.

 

4. Results and Discussion

The data are analyzed and Stewart method and Kay’s mixing rules for predicting pseudo-reduce pressure and temperatures are used for these data with knowing composition. Moreover, according to present of non-hydrocarbon on the data I used the correction methods which are Wichert- Aziz and Carr-Kobayashi and Burrows

The data of three reservoirs (A,B,C) with water vapor, carbon dioxide and hydrogen sulfide but with light molecular weight while ,the others (D,E,F) have C7+ and without water vapor are shown in table 2

In addition, gas pseudo-critical pressure increase with increase N2 and H2S as shown in figure 5,8. Also, it is observed that in the tested gas reservoirs which contain C7+ by Stewart Mixing Rules and Kay’s there are some deviation on z factor between two methods that became negligible by using the correction method for non-hydrocarbon as shown in figure 8 and table 10,14.

Conclusion

Natural gases, which contain H2S and CO2 frequently, exhibit different compressibility factor behavior than do sweet gases. Wichert and Aziz & Carr-Kobayashi and Burrows developed a simple procedure to account for these differences and adjust the pseudo-critical properties of natural gases. During this study, I observe that pseudo-critical temperature decreases if the mole percent of N2 increase. While, pseudo-critical pressure was increase with increasing the percentage of nitrogen. Also, the z factor increases with increasing pseudo- reduce pressure and temperature. In addition, pseudo-critical temperature decreases if the mole percent of H2S increase. I also notice that when I calculate the z-factor for reservoirs which contain C7+ by Stewart Mixing Rules and Kay’s there are some deviation on z factor between two methods but it reduces when I used the correction method for non-hydrocarbon.

Nomenclature

A: Mole fraction (H2S+CO2)

B: Mole fraction of H2S

P: pressure, psia

Pc: critical pressure, psia

Ppr: pseudo-reduced pressure

Ppc: pseudo-critical pressure, psia

P’pc: corrected pseudo- critical pressure, psia

T: Temperature, R0

Tc: critical temperature, R0

Tpr: pseudo-reduced temperature, R0

Tpc: Pseudo-critical temperature, R0

T’pc: corrected pseudo-critical temperature, R0

Ɛ: pseudo-critical temperature adjustment factor

CO2: Carbon Dioxide

 





Figure 1: Standing and Katz Compressibility Factors Chart





Figure 2: show the pseudo-critical property correction for H2S and CO2.




Figure 3: Show the pseudo-critical property of natural gases.




Figure 4: show the mole percent of nitrogen verses pseudo-critical temperature.





Figure 6: show the Z-factor verses pseudo-reduce temperature & pressure.






  Figure 7: show the mole percent of H2S verses pseudo-critical temperature.




Figure 5: show the mole percent of nitrogen verses pseudo-critical Pressure.




Figure 8: Z-factor obtained from Stewart & Kay and correction with impurities verses pseudo-critical temperature& pressure.



 

component

 

Molecular weight

 

 

Critical pressure

(Psia)

 

Critical Temperature(Ro)

H2S

34.08

1300

672.45

CO2

44.01

1071

547.45

N2

28.01

493

227.27

C1

16.04

667.8

343.04

C2

30.07

707.8

549.76

C3

44.01

616.3

665.68

i-C4

58.12

529.1

734.65

n-C4

58.12

550.7

765.32

i-C5

72.15

490.4

828.77

n-C5

72.15

488.6

845.37

C6

86.18

436.9

913.37

Table 1: Physical Properties of defined component.

 

 

 

A

 

B

 

C

 

D

 

E

 

F

Pressure(psia)

6000

5200

5000

4010

2640

2748

Temperature (Ro)

673.8

657.6

657.6

711.6

672

690

C1

59.59

69.14

71.32

57.95

61.83

40

C2

0.02

2.27

0.1

12.59

7.7

11.93

C3

0.01

1.96

0

7.94

7.63

14

i-C4

0

0.46

0

1.13

1.73

4.7

n-C4

0

1.46

0

3.16

4.38

7.37

i-C5

0

0

0

1.42

2.38

2.38

n-C5

0

0

0

2.01

2.6

5.6

C6

0

0

0

2.18

4.34

7.54

C7+

0

0

0

4.54

6.87

5.93

CO2

12.59

7.9

9.05

3.9

0.3

0.34

N2

11.95

0.1

6.35

0.2

0.24

0.21

H2S

12.09

13.03

9.44

2.98

0

0

H2O

3.75

3.68

3.74

0

0

0

Table 2: Six different reservoir in Abu-Dhabi.

so I used Stewart et al. Mixing Rules and Kays, The calculation and result for six reservoir are appear in tables 3 to14.

Table 3: Reservoir A using Kay’s Rule at P=6000 psi and T=673.8 Ro

 

 

component

 

Yi

 

Mi

 

YiMi

 

Tci

 

YiTci

 

Pci

 

YiPci

CO2

0.1259

44

5.5396

547.6

68.94284

1071

134.8389

N2

0.1198

28

3.3544

239.3

28.66814

507.5

60.7985

H2S

0.1209

34

4.1106

672.35

81.287115

1306

157.8954

H20

0.0375

18

0.675

1164.85

43.681875

3200.1

120.00375

C1

0.5956

16

9.5296

343

204.2908

666.4

396.90784

C2

0.0002

30

0.006

549.6

0.10992

706.5

0.1413

C3

0.0001

45

0.0045

665.7

0.06657

616

0.0616

i-C4

0

58

0

734.1

0

527.9

0

n-C4

0

58

0

765.3

0

550.6

0

Total

1

 

23.2197

 

427.04726

 

870.64729

Table 4: Reservoir B using Kay’s Rule at P=5200psi and T=657.6 Ro

 

 

component

 

Yi

 

Mi

 

YiMi

 

Tci

 

YiTci

 

Pci

 

YiPci

CO2

0.079

44

3.476

547.6

43.2604

1071

84.609

N2

0.001

28

0.028

239.3

0.2393

507.5

0.5075

H2S

0.1303

34

4.4302

672.35

87.607205

1306

170.1718

H20

0.0368

18

0.6624

1164.85

42.86648

3200.1

117.76368

C1

0.6914

16

11.0624

343

237.1502

666.4

460.74896

C2

0.0227

30

0.681

549.6

12.47592

706.5

16.03755

C3

0.0196

45

0.882

665.7

13.04772

616

12.0736

i-C4

0.0046

58

0.2668

734.1

3.37686

527.9

2.42834

n-C4

0.0146

58

0.8468

765.3

11.17338

550.6

8.03876

Total

1

 

22.3356

 

451.19747

 

872.37919

Table 5: Reservoir C using Kay’s Rule at P=5000psi and T=657.6 Ro

 

 

 

 

component

 

Yi

 

Mi

 

YiMi

 

Tci

 

YiTci

 

Pci

 

YiPci

CO2

0.0905

44

3.982

547.6

49.5578

1071

96.9255

N2

0.0635

28

1.778

239.3

15.19555

507.5

32.22625

H2S

0.0944

34

3.2096

672.35

63.46984

1306

123.2864

H20

0.0374

18

0.6732

1164.85

43.56539

3200.1

119.68374

C1

0.7132

16

11.4112

343

244.6276

666.4

475.27648

C2

0.001

30

0.03

549.6

0.5496

706.5

0.7065

C3

0

45

0

665.7

0

616

0

i-C4

0

58

0

734.1

0

527.9

0

C5

0

72

0

828.77

0

490.4

0

Total

1

 

21.084

 

416.96578

 

848.10487

Table 6: Properties and Compressibility factor for the three Reservoirs.

 

 

 

A

 

B

 

C

PPc

870.647

872.379

848.105

TPc

427.047

451.197

416.966

PPr

6.891

5.961

5.895

TPr

1.578

1.457

1.577

Z

0.928

0.848

0.872

Tpc'

400.563

426.246

394.149

Ppc'

811.305

819.004

797.964

Tp''

376.709

412.673

373.208

PP''

778.462

774.854

756.788

Tr

1.789

1.594

1.762

Pr

7.708

6.711

6.607

z

1.004

0.920

0.946

Table 7: Reservoir D using Stewart Mixing Rules.

 

 

Component

 

Yi

 

Mi

 

yiMi

 

Tci (â—¦R)

 

Pci (psia)

 

yiTci/Pci

 

yi√Tci/Pci

 

yiTci/√Pci

N2

0.002

28.01

0.06

227.16

493.10

0.00

0.00

0.02

CH4

0.5795

16.04

9.30

343.00

666.40

0.30

0.42

7.70

C2H6

0.1259

30.07

3.79

549.59

706.50

0.10

0.11

2.60

C3H8

0.0794

44.10

3.50

665.73

616.00

0.09

0.08

2.13

i-C4H10

0.0113

58.12

0.66

734.13

527.90

0.02

0.01

0.36

n-C4H10

0.0316

58.12

1.84

765.29

550.60

0.04

0.04

1.03

i-C5H12

0.0142

72.15

1.02

828.77

490.40

0.02

0.02

0.53

n-C5H12

0.0201

72.15

1.45

845.47

488.60

0.03

0.03

0.77

C6H14

0.0218

86.18

1.88

913.27

436.90

0.05

0.03

0.95

C7+

0.0454

114.23

5.19

1005.30

375.50

0.12

0.07

2.36

CO2

0.039

44.01

1.72

547.45

1071.00

0.02

0.03

0.65

H2S

0.0298

34.00

1.01

672.35

1306.00

0.02

0.02

0.55

1

 

30.39

 

 

0.80

0.86

19.66

Table 8: Reservoir E using Stewart Mixing Rules.

 

 

Component

 

Yi

 

Mi

 

yiMi

 

Tci (â—¦R)

 

Pci (psia)

 

yiTci/Pci

 

yi√Tci/Pci

 

yiTci/√Pci

N2

0.0024

28.01

0.07

227.16

493.10

0.00

0.00

0.02

CH4

0.6183

16.04

9.92

343.00

666.40

0.32

0.44

8.22

C2H6

0.077

30.07

2.32

549.59

706.50

0.06

0.07

1.59

C3H8

0.0763

44.10

3.36

665.73

616.00

0.08

0.08

2.05

i-C4H10

0.0173

58.12

1.01

734.13

527.90

0.02

0.02

0.55

n-C4H10

0.0438

58.12

2.55

765.29

550.60

0.06

0.05

1.43

i-C5H12

0.0238

72.15

1.72

828.77

490.40

0.04

0.03

0.89

n-C5H12

0.026

72.15

1.88

845.47

488.60

0.04

0.03

0.99

C6H14

0.0434

86.18

3.74

913.27

436.90

0.09

0.06

1.90

C7+

0.0687

114.23

7.85

1005.30

375.50

0.18

0.11

3.56

CO2

0.003

44.01

0.13

547.45

1071.00

0.00

0.00

0.05

1

 

34.40

   

0.91

0.91

21.26

Table 9: Reservoir F using Stewart Mixing Rule.

 

 

Component

 

Yi

 

Mi

 

yiMi

 

Tci (â—¦R)

 

Pci (psia)

 

yiTci/Pci

 

yi√Tci/Pci

 

yiTci/√Pci

N2

0.00

28.01

0.06

227.16

493.10

0.00

0.00

0.02

CH4

0.40

16.04

6.42

343.00

666.40

0.21

0.29

5.31

C2H6

0.12

30.07

3.59

549.59

706.50

0.09

0.11

2.47

C3H8

0.14

44.10

6.17

665.73

616.00

0.15

0.15

3.76

i-C4H10

0.05

58.12

2.73

734.13

527.90

0.07

0.06

1.50

n-C4H10

0.07

58.12

4.28

765.29

550.60

0.10

0.09

2.40

i-C5H12

0.02

72.15

1.72

828.77

490.40

0.04

0.03

0.89

n-C5H12

0.06

72.15

4.04

845.47

488.60

0.10

0.07

2.14

C6H14

0.08

86.18

6.50

913.27

436.90

0.16

0.11

3.29

C7+

0.06

114.23

6.77

1005.30

375.50

0.16

0.10

3.08

CO2

0.00

44.01

0.15

547.45

1071.00

0.00

0.00

0.06

1.00

 

42.43

 

 

1.07

0.99

24.92

Table 10: Properties and Compressibility factor for the three Reservoirs.

 

 

 

D

 

E

 

F

Fj

0.044

0.070

0.059

Ej

0.007

0.002

0.004

Ek

0.355

0.397

0.380

J

0.762

0.851

1.017

K

19.660

21.256

24.924

J'

0.756

0.849

1.013

K'

19.305

20.859

24.544

Tpc

493.256

512.496

594.900

Ppc

652.851

603.662

587.495

Tpc'

481.534

511.864

594.193

Ppc'

636.898

602.917

586.797

Tp''

493.263

511.958

594.448

PP''

653.206

602.792

586.654

Tr

1.478

1.313

1.161

Pr

6.296

4.379

4.684

Z

0.874

0.690

0.666

Table 11: Reservoir D using Kay’s Mixing Rules.

 

 

Component

 

yi

 

Mi

 

Tci (â—¦R)

 

Pci (psia)

 

yiTci

 

yiPci

N2

0.002

28.0

227.2

493.1

0.5

1.0

CH4

0.580

16.0

343.0

666.4

198.8

386.2

C2H6

0.126

30.1

549.6

706.5

69.2

88.9

C3H8

0.079

44.1

665.7

616.0

52.9

48.9

i-C4H10

0.011

58.1

734.1

527.9

8.3

6.0

n-C4H10

0.032

58.1

765.3

550.6

24.2

17.4

i-C5H12

0.014

72.2

828.8

490.4

11.8

7.0

n-C5H12

0.020

72.2

845.5

488.6

17.0

9.8

C6H14

0.022

86.2

913.3

436.9

19.9

9.5

C7+

0.045

114.2

1005.3

375.5

45.6

17.0

CO2

0.039

44.0

547.5

1071.0

21.4

41.8

H2S

0.030

34.0

672.4

1306.0

20.0

38.9

1.000

 

8097.5

7728.9

489.5

672.4

Table 12: Reservoir E using Kay’s Mixing Rules.

 

 

Component

 

yi

 

Mi

 

Tci (â—¦R)

 

Pci (psia)

 

yiTci

 

yiPci

N2

0.0024

28.0

227.2

493.1

0.5

1.2

CH4

0.6183

16.0

343.0

666.4

212.1

412.0

C2H6

0.077

30.1

549.6

706.5

42.3

54.4

C3H8

0.0763

44.1

665.7

616.0

50.8

47.0

i-C4H10

0.0173

58.1

734.1

527.9

12.7

9.1

n-C4H10

0.0438

58.1

765.3

550.6

33.5

24.1

i-C5H12

0.0238

72.2

828.8

490.4

19.7

11.7

n-C5H12

0.026

72.2

845.5

488.6

22.0

12.7

C6H14

0.0434

86.2

913.3

436.9

39.6

19.0

C7+

0.0687

114.2

1005.3

375.5

69.1

25.8

CO2

0.003

44.0

547.5

1071.0

1.6

3.2

1

 

7425.2

6422.9

504.0

620.2

Table 13: Reservoir F using Kay’s Mixing Rules.

 

 

Component

 

yi

 

Mi

 

Tci (â—¦R)

 

Pci (psia)

 

yiTci

 

yiPci

N2

0.0021

28.0

227.2

493.1

0.5

1.0

CH4

0.4

16.0

343.0

666.4

137.2

266.6

C2H6

0.1193

30.1

549.6

706.5

65.6

84.3

C3H8

0.14

44.1

665.7

616.0

93.2

86.2

i-C4H10

0.047

58.1

734.1

527.9

34.5

24.8

n-C4H10

0.0737

58.1

765.3

550.6

56.4

40.6

i-C5H12

0.0238

72.2

828.8

490.4

19.7

11.7

n-C5H12

0.056

72.2

845.5

488.6

47.3

27.4

C6H14

0.0754

86.2

913.3

436.9

68.9

32.9

C7+

0.0593

114.2

1005.3

375.5

59.6

22.3

CO2

0.0034

44.0

547.5

1071.0

1.9

3.6

1

 

6877.7

5351.9

584.8

601.4

Table 14: Properties and Compressibility factor for the three Reservoirs.

 

 

 

D

 

E

 

F

Fj

0.044

0.070

0.059

Ej

0.007

0.002

0.004

Ek

0.355

0.397

0.380

J

0.762

0.851

1.017

K

19.660

21.256

24.924

J'

0.756

0.849

1.013

K'

19.305

20.859

24.544

Tpc

493.256

512.496

594.900

Ppc

652.851

603.662

587.495

Tpc'

481.534

511.864

594.193

Ppc'

636.898

602.917

586.797

Tp''

493.263

511.958

594.448

PP''

653.206

602.792

586.654

Tr

1.478

1.313

1.161

Pr

6.296

4.379

4.684

Z

0.874

0.690

0.666

Table 10: Properties and Compressibility factor for the three Reservoirs.

 

 

– 

 

D

 

E

 

F

Tpc

489.453

504.005

584.759

Ppc

672.432

620.215

601.395

Tpc'

477.731

503.373

584.052

Ppc'

655.874

619.437

600.668

Tp''

477.741

503.446

584.759

PP''

655.876

619.352

601.395

Tr

1.490

1.335

1.181

Pr

6.114

4.263

4.576

Z

0.865

0.691

0.663

Table 14: Properties and Compressibility factor for the three Reservoirs.

 

 

 

 

 

 

Citation: Ghareb M. Hamada (2016) Effect of Non-hydrocarbon components on Gas Compressibility Factor Values and Correlations. Petro and Envi Biotech, APEB-101. DOI: 10.29011/2574-7614. 100101

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