Research Article Phase Behavior and Physical Parameters of ...downloads.hindawi.com/journals/jchem/2015/873718.pdf · ( ) Two- ash experiments and CCE experiments were also performed

Research ArticlePhase Behavior and Physical Parameters of Natural GasMixture with CO2

Dali Hou123 Hucheng Deng12 Hao Zhang12 Kai Li12 Lei Sun3 and Yi Pan3

1School of Energy Resources Chengdu University of Technology Chengdu Sichuan 610059 China2The State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation Chengdu University of Technology ChengduSichuan 610059 China3The State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation Engineering Southwest Petroleum UniversityXindu Avenue No 8 Chengdu Sichuan 610500 China

Correspondence should be addressed to Dali Hou houdali08163com

Received 3 January 2015 Revised 28 March 2015 Accepted 4 April 2015

Academic Editor Christophe Coquelet

Copyright copy 2015 Dali Hou et alThis is an open access article distributed under the Creative CommonsAttribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The two-flash experiment constant composition expansion experiment saturation pressure measurement experiment and phasetransition observation experiment from well bottom hole to well head of four high CO

2content natural gas samples were carried

out by using the JEFRI-PVT apparatus made from DBR Company of Canada The experimental results show that in the four highCO2content gas samples no phase transitions will take place at temperatures greater than 35∘C In the gas-liquid two-phase region

saturation pressures critical pressure critical temperature and an integrated P-T phase diagram of different CO2content natural

gases are calculated by using the modified PR equation of state and modified (T) equation proposed by Saffari The deviationsbetween the saturation pressure calculated by using the model proposed in this study and experimental measured saturationpressure are very small the average relative error is only 286 Thus the model can be used to predict the phase equilibriumparameters of high CO

2content natural gas

1 Introduction

With the increasing demand of CO2resource exploration

and development of high CO2content gas reservoirs are

becoming one part of the future oil-gas strategy [1] Currentlythe discovered high CO

2content gas reservoirs in the world

aremainly distributed over the Pacific such as Japan Indone-sia New Zealand Philippines Vietnam Thailand MalaysiaAustralia Mexico America and Canada [2ndash5] Twenty-eighthigh CO

2content gas reservoirs have been discovered in

China and they aremainly distributed in oil-bearing basins inthe east of China in which the high CO


reserve is 20000 times 108m3 in Songliao basin [6] FurthermoreCO2content in Changling Gudian Honggang Shengping

Fangshen and other gas reservoirs in Jilin oilfield of Songliaobasin can even range from 20mol to 90mol [7ndash9] HighCO2content natural gas reservoir is very special and devel-

opment is very difficult whichmainly reflects in the variation

of fluid phase behavior The research of some scholars athome and abroad focuses on the physical parameters anddevelopment index of the CO

2contents in natural gas [7 9ndash

14] but seldom focus is directed on the phase behavior ofnatural gases with high CO

2content and the phase behavior

of natural gas with high CO2content is not entirely clear at

present [15ndash19] Thus it is one of basic research topics onthe experimental measured saturation pressure to determinewhether any phase transitions in natural gases with highCO2content take place from formation to well head and the

physical parameters of high CO2content natural gases for

high-efficient developing the gas reservoirs with high CO2

contentIt is revealed in this paper whether any phase transition in

high CO2content natural gases takes place in the exploitation

process The saturation pressures of different CO2content in

natural gases at different temperatures are measured by usingtheDBR-PVT apparatus and the saturation pressures critical

Hindawi Publishing CorporationJournal of ChemistryVolume 2015 Article ID 873718 11 pageshttpdxdoiorg1011552015873718

2 Journal of Chemistry

pressures critical temperatures and an integrated 119875-119879 phasediagram of different CO

2content natural gases are calculated

by using themodified PR equation of state andmodified 120572(119879)equation proposed by Saffari And the deviations between thesaturation pressure calculated by using the model proposedin this paper and experimental measured saturation pressureare analyzed Also revealed in this paper is the influenceof different CO

2content in natural gases on the 119875-119879 phase

diagrams and critical points Furthermore the variationlaw and affecting factors of the physical parameters suchas relative volume 119885-factor formation volume factor anddensity of high CO

2content natural gases are discussed in

this paper

2 Theories

By modifying the attractive term in the RedlickndashKwongequation of state Peng and Robinson were able to enhancethe model prediction of experimental data Since its incep-tion Peng-Robinson EOS has been widely used to estimatethermodynamic properties for hydrocarbon systems It reads[20 21] as

119875 =

119877119879

V minus 119887minus

119886 (119879)

V (V + 119887) + 119887 (V minus 119887) (1)

where 119875 is pressure 119879 is temperature V is the molar volume119877 is the gas constant and 119886(119879) and 119887 are the parameters of theEOS At constant119875 and119879 the equation will take the form of acubic equation in V and can be solved for V using any standardanalytical or numerical technique [22] The limitations oncritical point lead to the following relations for the PR-EOSparameters [20]

119886 (119879) = 119886 (119879119888) 120572 (119879)

119886 (119879119888) =

04572411987721198792

119888

119875119888

119887 = 00778

119877119879119888

119875119888

(2)

where subscript 119888 indicates critical property and 120572(119879) istemperature dependent In this work we use the new 120572-function proposed by Saffari which is written as [23]

120572 (119879) = exp [1198961119879119903+ 1198962ln119879119903+ 1198963(1 minus 119879

12

119903)] (3)

119879119903=

119879

119879119888

(4)

The new 120572-functions proposed are exponential functionseachwith three adjustable parameters 119896

1 1198962 and 119896

3 Since the

adjustable parameters determine attractive intermolecularinteractions in a pure component system the values of 119896

119894are

compound-specific and should be optimized for each purecomponent In this work we determine the optimum valuesof pure component parameters by minimizing the error ofvapor pressure predicted by using the modified PR equationof state and modified 120572(119879) equation proposed by Saffari with

0003

0004

0005

0006

0007

0008

0 01 02 03 04

Fitted parametersLiner (fitted parameters)

y = 00113x + 00033

R2 = 09092

k1

120596

Figure 1 Linear trend of fitted parameter 1198961of the 120572-function

equation (3)

002

005

008

011

014

017

02

0 01 02 03 04minus001


y = 04106x + 00085

R2 = 06841

120596

k2


equation (3)

respect to the experimental values in the temperature rangefrom triple point to critical point [23]

Andweuse the individually optimized parameters of purecomponents for the new 120572-function proposed in this work(3) to develop generalized equations in terms of the acen-tric factor 120596 Pure component constants including criticalproperties and vapor pressure data are obtained from Polinget al [24] Yaws [25] and Smith and Srivastava [26] Theadjustable parameters of the new 120572-function proposed bySaffari have been fitted to experimental vapor pressure datagiven in Table 1

And then the parameters 1198961 1198962 and 119896

3are generalized

as a function of acentric factor 120596 Acentric factor of a purecomponent is obtained from Poling et al [24] Figures 1ndash3show the trend of fitted parameters presented inTable 1 versusthe acentric factor as well as a linear fit and the 119877-squared

Journal of Chemistry 3

Table 1 Optimized parameters of the new 120572-function proposed by Saffari (3)

Substance 119879119903range Optimized parameters

1198961

1198962

1198963

CO2 072ndash1 00056 00881 14928N2 052ndash1 00033 minus00031 08180methane 048ndash1 00039 00473 08514ethane 030ndash1 00047 00359 10638propane 026ndash1 00050 01010 13640i-butane 028ndash1 00052 00730 14200n-butane 033ndash1 00054 00780 14205i-pentane 025ndash1 00060 00885 15626n-pentane 031ndash1 00059 00872 15624hexane 036ndash1 00072 01731 18759

Table 2 Composition of various gas mixtures and the critical properties of the related component

Components Gas1 YP9 Gas2 Gas3 119875119888

119879119888

120596

(mol) (mol) (mol) (mol) (MPa) (K)CO2 10045 21746 55535 75323 7376 3042 0225N2 1474 271 2056 0971 3394 1262 0040C1 84718 73604 40891 23014 4600 1906 0008C2 2973 1127 0941 0422 4884 3054 0098C3 0532 0492 0235 0092 4246 3698 0152iC4 0064 0006 0299 0034 3640 4081 0176nC4 0058 0301 0004 0042 3800 4252 0193iC5 0026 0003 0005 0047 3384 4604 0227nC5 0052 0005 0003 0033 3374 4696 0251C6 0058 0006 0031 0022 2969 5074 0296Note gas sample with CO2 content of 10045mol is made from YP9 and dry natural gas and gas sample with CO2 content of 55535mol or 75323mol ismade from YP9 and pure industrial carbon dioxide (purity gt 9999)

Consequently the final form of new 120572-function with thegeneralized parameters for natural gas components can bewritten as

120572 (119879) = exp [1198961119879119903+ 1198962ln119879119903+ 1198963(1 minus 119879

12

119903)]

1198961= 00113120596 + 00033

1198962= 04106120596 minus 00085

1198963= 3541120596 + 07532

(5)

Extending PR-EOS to mixtures requires replacementof coefficients 119886 and 119887 by the following van der Waalscomposition-dependent mixing rules [20]

119886 =

119899

sum

119894

119899

sum

119895

119909119894119909119895119886119894119895

119887 =

119899

sum

119895

119909119894119887119894

(6)

The unlike-interaction parameter 119886119894119895 formed between

component 119894 and component 119895 can be related to the pure

components parameter with an extra fitting coefficient (119896119894119895)

known as the coupling parameter

119886119894119895= (1 minus 119896

119894119895) (119886119894119886119895)

12

(7)

3 Experiments

31 Sample Experimental gas samples were divided into 4groups one group was directly taken from surface separatorof YP9 well in Jilin gas field and the other three groups(Gas1 Gas2 and Gas3) were made from YP9 dry naturalgas and pure industrial carbon dioxide (purity gt 9999)The detailed synthetic process refers to SYT6434-2000 [27]The initial formation pressure and formation temperatureof YP9 well are respectively 4234MPa and 1275∘C Thecomponents of four groups of gas samples were analyzedby using HP-6890 gas chromatography and Shimadzu GC-14A gas chromatography The results are shown in Table 2The critical pressure and temperature [28 29] of the purecomponents which are normally presented in natural gas arealso listed in Table 2 The contents of CO

2in YP9 well Gas1

Gas2 and Gas3 are respectively 21746mol 10045mol55535mol and 75323mol The CO

2content in natural

gas being more than 10mol is usually called the high CO2


05

08

11

14

17

2

0 01 02 03 04120596

k3

y = 3541x + 07532

R2 = 09656



equation (3)

content natural gas [30]ThusThe four groups of gas samplesare all the high CO

2content gas samples

32 Apparatus The experimental facility is a mercury-freehigh pressure PVT system made by the DBR CompanyCanadaA schematic diagramof the corresponding apparatusis given in Figure 4 It is mainly characterized by the visualobservation of experimental phenomena and the speciallydesigned piston in the PVT cell that allows us to preciselymeasure even minute liquid The system is mainly made upof a PVT cell thermostatic air bath pressure sensor temper-ature sensor flash separator electronic balance gasometergas chromatography sample container automatic pump andoperation control system Sample container is made fromsapphire glass

The volume of fluid in the PVT cell can be calculatedby the internal cross-sectional area of sapphire glass cylindermultiplied by the height of the fluid which was measured bythe grating altimeter

The physical parameters of main parts are as followsPVT cells maximal working pressure is 70MPa the

highest operating temperature is 200∘C the lowest operatingtemperature isminus100∘C andmaximal volume is about 150 cm3

Pressure sensor It is 0sim100MPa and precision of pres-sure control is 1 Psi

Temperature sensor it is minus100sim200∘C and precision oftemperature control is plusmn01∘C

Thermostatic air bath the highest operation temperatureis 200∘C and precision of temperature control is plusmn01∘C

Sample container it is 130 cm3Automatic pump rated operation pressure is 100MPa

with resolution of 1 Psi and the range of operation pumpvolume is 500 cm3 with resolution of 0001 cm3

Electronic balance it is 0sim500 g and precision of weightcontrol is 0001 g

The accuracy of PVTmain parts satisfies the phase behav-ior experimental requirement of the synthetic gas samplewith different CO

2content [31]

33 Experimental Procedures Experimental procedures areas follows

(1) Clean PVT vessel and cells then connect the PVTvessel to cells and evacuate the cells

(2) Prepare the gas samples and control andmaintain thedesired temperature using the constant temperatureair bath

(3) Introduce a test gas about 50mL (YP9 gas sample)into PVT vessel at the specified temperature andpressure in the oven and keep it for 5 h and then holdon an hour and measure the gas volume of the PVTvessel

(4) Two-flash experiment slightly open the valvebetween the cells and bleed gas from the PVT vesselinto the flash separators at the same time and keepthe pressure using the automatic pump at formationtemperature (1275∘C)

(5) Record the bled gas volumes using the gasometer andremaining gas volumes of PVT vessel

(6) The bled gas was analyzed using gas chromatograph(7) Constant composition expansion experiment (CCE

experiment) or 119875-119881 relationship experiment pres-sure was reduced step by step from initial formationpressure to the limit pressure of the piston movementunder the formation temperature The volumes wererecorded when each pressure was stable

(8) Step (7) was repeated at 35∘C 75∘C and 1275∘Crespectively 119875-119881 relationship experiment was testedat least three times under each temperature and theaverage value was calculated

(9) Two-flash experiments and CCE experiments werealso performed on the other three gas samples byrepeating step (3) to step (8)

(10) The gas sample with the highest content of CO2

(75323mol) was introduced into the PVT vessel tostudy whether phase transition in high CO

2content

natural gas takes place from formation to well headThe experimental temperatures are minus10∘C and 35∘Crespectively

4 Results and Discussion

41 Two-Flash andCCEExperiments Theresults of two-flashexperiments are listed in Table 3 Formation volumes (underthe formation conditions) and ground volumes (under thestandard conditions) are the experimental measurementsand density molecular weight formation volume factor and119885-factor are calculated by using gas state equation The gasstate equation is expressed as follows [27]

Under the formation conditions one has

119875119905119881119905= 119899119877119885

119905119879119905 (8)


32

87

65

9

4

1

(1) CO2 sample(2) High CO2 content natural gas(3) Without or low CO2 content natural gas(4) Thermostatic system(5) PVT cell

(6) Flash separator and electronic balance(7) Gasometer(8) Gas chromatography(9) Automatic pump

Figure 4 Schematic diagram of the experimental apparatus

Table 3 Results from two-flash experiments for different CO2 contents in natural gas

Parameters Gas1 YP9 Gas2 Gas3Formation volume119881

119905(cm3) 297 3951 3762 6676

Ground volume119881sc (cm3) 850 1135 1155 2160

Formation volume factor119861119892119905

0003496 0003481 0003257 0003091119885-factor119885

11990510702 10663 09885 09295

Gas density120588119905(kgm3) 23000 26851 39875 49413

(under the formation conditions)Molecular weight119872 (gmol) 1985 2249 3055 3592Relative density120574

11989206853 07763 10545 12398

Under the standard conditions one has

119875sc119881sc = 119899119877119885sc119879sc (9)

119875119905is the formation pressure 119881

119905is the gas volume under

the formation conditions 119885119905is the deviation factor under

the formation conditions 119879119905is the formation temperature

119899 is the number of moles 119877 is the gas general constant83147MPasdotcm3sdotmolminus1sdotKminus1 119875sc is the atmospheric pressureand it is usually approximately equal to 0101325MPa 119881scis the gas volume under the standard conditions 119885sc isthe deviation factor under the standard conditions andit is usually approximately equal to 1 119879sc is the standardtemperature and it is usually approximately equal to 20∘C

Relative densities are calculated by using the following[27]

120574119892=

119872

119872air (10)

119872 is the gas molecular weight119872air is the air molecularweight and it is usually approximately equal to 2897 gmol

We can draw the conclusion fromTable 3 that the densitymolecular weight and relative density increase with increas-ing CO

2content in natural gas while the formation volume

factor and 119885-factor decrease with increasing CO2content in

natural gasCCE experiment was performed to draw the relative

volume 119885-factor formation volume factor and densityunder the grading pressure And the results are shown fromFigures 5ndash12

411 Effect of Temperature The effect of temperature on thephysical properties of YP9 gas samplewas respectively testedunder the formation temperature (1275∘C) the temperaturein the well (75∘C) and the ground temperature (35∘C)It can be seen from Figures 5ndash7 that the relative volumeand formation volume factor of high CO

2content natural

gases increase with increasing temperature under constantpressure while the density of gas decreases with increas-ing temperature under constant pressure And the relativevolume and formation volume factor of high CO

2content

natural gases decrease with increasing pressure at isothermal


000

100

200

300

400

500

600

0 10 20 30 40 50

Rela

tive v

olum

e

Pressure (MPa)

35∘C75∘C

1275∘C

Figure 5 Variation of the relative volume of YP9 gas sample withpressure under different temperatures

0000

0005

0010

0015

0020

0025

0030

0 10 20 30 40 50

Form

atio

n vo

lum

e fac

tor

Pressure (MPa)

35∘C75∘C

1275∘C

Figure 6 Variation of the formation volume factor of YP9 gassample with pressure under different temperatures

conditions The effects of temperature and pressure on theexperimental 119885-factors for YP9 gas sample are shown inFigure 8 It can be seen clearly form Figure 8 that 119885-factordecreases with increasing pressure at lower pressure rangethat is less than 18MPa while it increases with increasingpressure at higher pressures that is higher than 18MPa Andthe 119885-factor decreases with decreasing temperature and agreater decrease can be observed in a pressure range fromabout 15MPa to 22MPa [32]

412 Effect of CO2Content Experimental relative volumes

formation volume factors and densities of different CO2

content natural gases are shown from Figures 9ndash11 It can beseen clearly from Figures 9ndash11 that relative volume and for-mation volume factor decrease with increasing CO

2content

000

005

010

015

020

025

030

035

040

045

050

0 10 20 30 40 50Pressure (MPa)

35∘C75∘C

1275∘C

Gas

den

sity

(gc

m3)

Figure 7 Variation of the gas density of YP9 gas sample withpressure under different temperatures

070

080

090

100

110

0 10 20 30 40 50

Gas

com

pres

sibili

ty fa

ctor

Pressure (MPa)

35∘C75∘C1275∘C

Figure 8 Variation of the119885-factor of YP9 gas sample with pressureunder different temperatures

in natural gas at 1275∘C isothermal and constant pressureconditions but they do not change insignificantlyThe effectsof CO

2content in natural gas on the experimental 119885-factors

of different CO2content natural gases are shown in Figure 12

It can be seen from Figure 12 that 119885-factor decreases withincreasing CO

2content in natural gas at 1275∘C isothermal

and constant pressure conditions And the dependence of thepressure follows the same trends as mentioned in Figure 5

42 Effect of CO2Content on 119875-119879 Diagram In order to test

and draw the 119875-119879 phase diagram of the high CO2con-

tent natural gas we have tested saturation pressures of thehigh CO

2content natural gases at different temperatures

(minus60∘C minus50∘C minus40∘C minus30∘C minus20∘C minus10∘C and 0∘C) based


Table 4 Saturation pressure calculated by using the model proposed in this paper and experimental measured saturation pressure

ParametersGas1 YP9 Gas2 Gas3

Calculatedvalue

Measuredvalue

Calculatedvalue

Measuredvalue

Calculatedvalue

Measuredvalue

Calculatedvalue

Measuredvalue

(MPa) (MPa) (MPa) (MPa) (MPa) (MPa) (MPa) (MPa)Saturation pressure (minus60∘C) 621 605 628 611 488 462 Saturation pressure (minus50∘C) 675 668 705 692 569 551 399 375Saturation pressure (minus40∘C) 608 601 688 698 648 666 468 445Saturation pressure (minus30∘C) 732 715 542 565Saturation pressure (minus20∘C) 813 845 623 635Saturation pressure (minus10∘C) 848 865 708 695Saturation pressure (0∘C) 785 802Note ldquordquo shows that no saturation pressure is measured and calculated

000

100

200

300

400

500

600

700

0 10 20 30 40 50

Rela

tive v

olum

e

Pressure (MPa)

Gas1YP9

Gas2Gas3

Figure 9 Variation of the relative volume of different CO2content

natural gas samples with pressure at 1275∘C

Gas1YP9

Gas2Gas3

000

001

001

002

002

003

0 10 20 30 40 50

Form

atio

n vo

lum

e fac

tor

Pressure (MPa)

Figure 10 Variation of the volume factor of different CO2content


000

010

020

030

040

050

060

0 10 20 30 40 50Pressure (MPa)

Gas

den

sity

(gc

m3)

Gas1YP9

Gas2Gas3

Figure 11 Variation of the gas density of different CO2content


on the above CCE experimental test methods The testresults are shown in Table 4 At the same time saturationpressures at the corresponding conditions are calculated byusing (1) to (7) and the tested saturation pressures are fittedby adjusting critical parameters (critical temperature andcritical pressure) of C

6on the basis of the fixed binary

interaction coefficients in the process of calculation thecalculated results are also shown in Table 4 C

6has several

isomers the critical parameters are not fixed so we choosethe critical parameters of C

6as adjustable parameters to

fit the saturation pressure of different CO2content natural

gases The fixed binary interaction coefficients are given inTable 6 and the critical parameters (critical temperatures andcritical pressures) of C

6are given in Table 7 It can be seen

from Table 7 that the higher the CO2content the higher

the critical temperature the lower the critical pressure andthe heavier the system (different CO

2content natural gas)

And we compare the saturation pressure calculated by usingthe model proposed in this paper with the experimentalmeasured saturation pressure the deviations between the


070

080

090

100

110

0 10 20 30 40 50

Gas

com

pres

sibili

ty fa

ctor

Pressure (MPa)

Gas1YP9

Gas2Gas3

Figure 12 Variation of the119885-factor of different CO2content natural

gas samples with pressure at 1275∘C

saturation pressure calculated by using the model proposedin this paper and experimental measured saturation pressureare shown in Table 5 The absolute relative error (11) andthe average absolute relative error (12) are used to expressthe deviation between the saturation pressure calculated byusing the model proposed in this paper and the experimentalmeasured saturation pressure We can draw the conclusionfrom Table 5 that the temperatures are colder the absoluterelative error is greater and the higher the CO

2content

in natural gas the greater the absolute relative error Theaverage relative errors of Gas1 YP9 Gas2 andGas3 are 162203 329 and 338 respectively Overall the deviationsbetween the saturation pressure calculated by using themodel proposed in this paper and experimental measuredsaturation pressure are very small the average relative errorof all the gas samples is 286 So it shows that the model canbe used to predict the 119875-119879 phase diagram of the high CO

2

content natural gas Consider

ARE () =119873

sum

119894=1

10038161003816100381610038161003816100381610038161003816

Cal minus ExpExp

10038161003816100381610038161003816100381610038161003816119894

times 100 (11)

AARE () = 1119873

119873

sum

119894=1

10038161003816100381610038161003816100381610038161003816

Cal minus ExpExp

10038161003816100381610038161003816100381610038161003816119894

times 100 (12)

119875-119879 diagrams and critical points of different CO2content

natural gases in the gas-liquid two-phase region were drawnusing (1) to (7) the calculated results are shown in Figures13 and 14 And 119875-119879 diagrams and critical points of puremethane and pure CO

2in Figures 13 and 14 refer to the

experimental data from the literature [33 34] In Figure 13the vapor-liquid critical locus exits in the pure CH

4critical

point extending continuously toward the CO2critical point

[35] Three-phase loci originating from triple-point of pureCO2ends in the triple-point of CH

4[35] Here we only

consider the gas-liquid two-phase region because it is found

00102030405060708090

100

5 45

Pres

sure

(MPa

)

minus10minus195 minus155 minus115 minus75 minus35

Temperature (∘C)

Calculated P-T phase diagrams (Gas1)Calculated P-T phase diagrams (YP9)Calculated P-T phase diagrams (Gas2)Calculated P-T phase diagrams (Gas3)Pure CO2 P-T phase diagramsPure CH4 P-T phase diagramsMeasured saturation pressure (Gas1)Measured saturation pressure (YP9)Measured saturation pressure (Gas2)Measured saturation pressure (Gas3)Three-phase lociCO2 triple pointCO2 critical pointCH4 triple pointCH4 critical pointVapor-liquid critical locus

Figure 13 Calculated 119875-119879 phase diagrams andmeasured saturationpressure of natural gas with different CO

2contents

3

4

5

6

7

8

9

10

10 30

Pres

sure

(MPa

)

minus90 minus70 minus50 minus30 minus10

Temperature (∘C)

CH4(100)

CO2(10045)

CO2(55535) CO2(75323)

CO2(100)CO2(21746)

Figure 14 Variation curve of the critical points of natural gas withdifferent CO

2contents

in the process of calculation that the model proposed inthis study is only applied to calculate the gas-liquid phaseequilibrium while it is not applied to calculate the gas-solid liquid-solid and gas-liquid-solid phase equilibriumWe can draw the conclusion from Figures 13 and 14 that asCO2content in natural gas increases the two-phase envelope


Table 5 The deviations between the saturation pressure calculated by using the model proposed in this paper and experimental measuredsaturation pressure

Parameters Gas1 Gas1 YP9 YP9 Gas2 Gas2 Gas3 Gas3 TotalARE AARE ARE AARE ARE AARE ARE AARE AARE

Saturation pressure (minus60∘C) 264

162

278

203

563

329

338 286

Saturation pressure (minus50∘C) 105 188 327 640Saturation pressure (minus40∘C) 116 143 270 517Saturation pressure (minus30∘C) 238 407Saturation pressure (minus20∘C) 379 189Saturation pressure (minus10∘C) 197 187Saturation pressure (0∘C) 212

Table 6 Binary interaction parameters (119896119894119895) and mixing rules for the model proposed in this study

Components CO2 N2 C1 C2 C3 iC4 nC4 iC5 nC5 C6

CO2 0 minus002 0103 0130 0135 0130 0130 0125 0125 0150N2 minus002 0 0031 0042 0091 0095 0095 0095 0095 0120C1 0103 0031 0 0003 0009 0016 0015 0021 0021 0025C2 013 0042 0003 0 0002 0005 0005 0009 0009 0012C3 0135 0091 0009 0002 0 0001 0001 0003 0003 0005iC4 013 0095 0016 0005 0001 0 0000 0000 0000 0001nC4 013 0095 0015 0005 0001 0000 0 0001 0001 0001iC5 0125 0095 0021 0009 0003 0000 0001 0 0000 0000nC5 0125 0095 0021 0009 0003 0000 0001 0000 0 0000C6 015 012 0025 0012 0005 0001 0001 0000 0000 zero

Table 7 The critical parameters (critical temperature and criticalpressure) of C6

Sample Critical temperature ∘C Critical pressure MPaGas1 23595 2934YP9 24245 2889Gas2 25565 2776Gas3 26895 2740

moves right and two-phase region becomes narrower Andcritical point of natural gas moves to upper right (reaching amaximum) and finally itmoves to lower rightThemaximumcritical pressure is 849MPa when CO

2is about 55535mol

The closer the distribution ratio of CH4and CO

2 the

larger the two-phase region Furthermore comparing thecontents of CH

4and CO

2 as one component becomes more

predominant the 119875-119879 diagram tends to approach the vaporpressure curve (119875-119879 diagram of one component) of themajorcomponent The critical pressure of natural gas with highCO2content increaseswith increasingCO

2content in natural

gas when CO2content in natural gas is below 55535mol

while the critical pressure of high CO2content natural gas

decreases with increasing CO2content in natural gas when

CO2content in natural gas is above 55523mol But the

critical temperature constantly increases with increasing CO2

content in natural gas

43 Phase Transition Observation Experiment It can be seenfrom Section 42 that the critical temperature increases with

increasing CO2content in natural gas And in order to

facilitate reducing the temperature we chose the gas samplewith CO

2content of 75323mol as the research object The

result of phase transition observation experiment is shownin Figures 15 and 16 We can draw the conclusion that phasetransition of gas sample with CO

2content of 75323mol

does not take place as pressure decreases from 4234MPa to5MPa at 35∘C isothermal conditions while phase transitionof gas sample with CO

2content of 75323mol takes place

as pressure decreases from 4234MPa to 5MPa at minus10∘Cisothermal conditionsThe phase transition process is shownin the red dotted line part in Figure 16 The state of naturalgas changes from the original transparent state into the mistThe testing results of phase transition observation experimentconsist with the calculation results and testing results inSection 42 and for the four gas samples no phase transitionswill take place at temperatures greater than 35∘C It alsosuggests that phase transition does not also take place at 75∘Cisothermal conditions and at 125∘C isothermal conditions Itis illustrated that in the four gas samples no gas-liquid phasetransition happens from bottom hole to well head

5 Conclusions

Conclusions are as follows

(1) For the four high CO2content gas samples no phase

transitionswill take place at temperatures greater than35∘C It is illustrated that in the four gas samples no


Gas sample

Piston

Pressure transmitting

The process of pressure drawdown (MPa)

medium

4234 37 32 25 21 19 16 13 10 5

Figure 15 Phase transition of high CO2content natural gas samples

(75323mol) in the process of pressure drawdown at 35∘C


Gas sample

Piston


medium

Phasetransition

20 18 654810121416

Figure 16 Phase transition of high CO2content natural gas sample

(75323mol) in the process of pressure drawdown at minus10∘C

gas-liquid phase transition happens frombottomholeto well head

(2) Relative volume and formation volume factor of fourgas samples in this paper decrease with increasingpressure at isothermal conditions while densities offour gas samples increase with increasing pressure atisothermal conditions At isothermal conditions 119885-factors of four gas samples decrease with increasingpressure at lower pressure range that is less than18MPa while they increase with increasing pressureat higher pressure range that is higher than 18MPa

(3) Relative volumes formation volume factors and 119885-factors of four gas samples increase with increasingtemperature at constant pressure conditions whiledensities of four gas samples decrease with increasingtemperature at constant pressure

(4) Formation volume factors and 119885-factors of fourgas samples decrease with increasing CO

2content

in natural gas at isothermal and constant pressureconditions but relative volumes and volume factorsdo not change insignificantly And densities of fourgas samples increase with increasing CO

2content

in natural gas at isothermal and constant pressureconditions

(5) The deviations between the saturation pressure cal-culated by using the model proposed in this paperand experimental measured saturation pressure are

very small the average relative error is only 286Thus the model can be used to predict the saturationpressure of high CO


(6) In the gas-liquid two-phase region as CO2content in

natural gas increases the two-phase envelope movesright and two-phase region becomes narrower Andcritical point of natural gas proposed in this papermoves to upper right (reaching amaximum) and thenmoves to lower right The maximum critical pressureis 849MPa when CO

2content is about 55535mol

Conflict of Interests

Here all the authors solemnly declare that there is no conflictof interests regarding the publication of this paper

Acknowledgments

The authors wish to acknowledge anonymous reviewersfor constructive comments and suggestions for improvingthis paper The authors also wish to thank the anonymousAssociate Editor for his handling of the paper and additionalsuggestions This work was supported by National Scienceand Technology Major Project of China (no 2011ZX05016-005-2) and a grant from the National Natural Science Foun-dation of China (no 50604011)

References

[1] Y Hu J F Du P Guo et al ldquoExperimental study on Z-factorof high CO

2content natural gasrdquo Journal of Southern Yangtze

University (Natural Science) vol 6 no 2 pp 192ndash194 2009[2] H Anping D Jinxing Y Chun Z Qinghua and N Yunyan

ldquoGeochemical characteristics and distribution of CO2gas fields

in Bohai Bay Basinrdquo Petroleum Exploration and Developmentvol 36 no 2 pp 181ndash189 2009

[3] T J Hughes M E Kandil B F Graham and E F MayldquoSimulating the capture of CO

2from natural gas new data and

improved models for methane + carbon dioxide + methanolrdquoInternational Journal of Greenhouse Gas Control vol 31 pp 121ndash127 2014

[4] H Sriyanta M A Malek M A Zulhairi et al ldquoOperationalchallenges in managing high CO

2content gas production in

Peninsular Malaysia operationsrdquo in Proceedings of the Inter-national Petroleum Technology Conference SPE 17082 BeijingChina March 2013

[5] S I Putu and P T Pertamina ldquoProducing high CO2gas content

reservoirs in Pertamina Indonesia using multi stage cryogenicprocessrdquo in Proceedings of the SPE Asia Pacific Oil and GasConference and Exhibition SPE 134278 Brisbane AustraliaOctober 2010

[6] S L Li and Y Hua Condensate Gas Exploration and Devel-opment Technology Sichuan Science and Technology PressChengdu China 2000

[7] X Q Bian ZMDu andY Tang ldquoExperimental determinationand prediction of the compressibility factor of highCO

2content

natural gas with and without water vaporrdquo Journal of NaturalGas Chemistry vol 20 no 4 pp 364ndash371 2011


[8] Y Su Y Tang Y Xiao H Song and X Zhang ldquoImpacts of CO2

content on the development indexes of volcanic gas reservoirsrdquoNatural Gas Industry vol 31 no 8 pp 69ndash72 2011

[9] X Q Bian and Z M Du ldquoExperimental study on the phasebehavior and fluid physical parameters of high CO

2-content

natural gasrdquo Xinjiang Petroleum Geology vol 34 no 1 pp 63ndash65 2013

[10] X Bian Z Du and Y Tang ldquoExperimental determination andprediction of the compressibility factor of high CO

2content


[11] A Jarrahian and E Heidaryan ldquoA new cubic equation of statefor sweet and sour natural gases even when composition isunknownrdquo Fuel vol 134 pp 333ndash342 2014

[12] M Gazzani E Macchi and G Manzolini ldquoCO2capture in nat-

ural gas combined cycle with SEWGS Part A Thermodynamicperformancesrdquo International Journal of GreenhouseGasControlvol 12 pp 493ndash501 2013

[13] C W Park S Y Won C G Kim and Y Choi ldquoEffect ofmixing CO

2with natural gas-hydrogen blends on combustion

in heavy-duty spark ignition enginerdquo Fuel vol 102 no 12 pp299ndash304 2012

[14] T H Wong M Rahim P J Anthony et al ldquoChallenges indetermination of water content and condensedwater in amulti-stacked sour gas field containing high CO

2content offshore

Malaysiardquo in Proceedings of the International PetroleumTechnol-ogy Conference SPE 14413 Bangkok Thailand November 2011

[15] C Q Li G Q Xue M Li et al ldquoApplication of gas wellproduction decline prediction methods to CO

2gas reservoirrdquo

Xinjiang Petroleum Geology vol 29 no 5 pp 613ndash615 2008[16] B D Al-Anazi G R Pazuki M Nikookar and A F Al-Anazi

ldquoThe prediction of the compressibility factor of sour and naturalgas by an artificial neural network systemrdquo Petroleum Scienceand Technology vol 29 no 4 pp 325ndash336 2011

[17] J A Rushing K E Newsham K C van Fraassen et al ldquoNat-ural gas z-factors at HPHT reservoir conditions comparinglaboratory measurements with industry-standard correlationsfor a dry gasrdquo in Proceedings of the CIPCSPE Gas TechnologySymposium Joint Conference SPE 114518 Calgary Canada June2008

[18] E Heidaryan J Moghadasi and M Rahimi ldquoNew correlationsto predict natural gas viscosity and compressibility factorrdquoJournal of Petroleum Science and Engineering vol 73 no 1-2pp 67ndash72 2010

[19] F Tabasinejad R G Moore S A Mehta Y Barzin J ARushing and K Edward ldquoDensity of high pressure and temper-ature gas reservoirs effect of non-hydrocarbon contaminantson density of natural gas mixturesrdquo in Proceedings of the SPEWestern Regional Meeting SPE 133595 Anaheim Calif USAMay 2010

[20] D-Y Peng and D B Robinson ldquoA new two-constant equationof staterdquo Industrial amp Engineering Chemistry Fundamentals vol15 no 1 pp 59ndash64 1976

[21] W A Fouad and A S Berrouk ldquoPhase behavior of sour nat-ural gas systems using classical and statistical thermodynamicequations of statesrdquo Fluid Phase Equilibria vol 356 pp 136ndash1452013

[22] M Spiegel S Lipschutz and J Liu Schaumrsquos Outline of Mathe-matical Handbook of Formulas and Tables McGraw-Hill NewYork NY USA 3rd edition 2008

[23] H Saffari and A Zahedi ldquoA new alpha-function for the Peng-Robinson equation of state application to natural gasrdquo Chinese

Journal of Chemical Engineering vol 21 no 10 pp 1155ndash11612013

[24] B E Poling J M Prausnitz and J P OrsquoConnellThe Propertiesof Gases and Liquids McGraw-Hill New York NY USA 2001

[25] C L Yaws Chemical Properties Handbook McGraw-Hill NewYork NY USA 1999

[26] B D Smith and R Srivastava Thermodynamic Data for PureCompounds Part A Hydrocarbons and Ketones Elsevier Ams-terdam The Netherlands 1986

[27] China National Oil and Gas Industry Standards SYT 6434-2000 Analysis for Natural Gas Reservoir Fluids Physical Prop-erties China National Oil and Gas Industry Standards 2000

[28] R C Reid J M Prausnitz and B E Poling The Propertiesof Gases and Liquids McGraw-Hill New York NY USA 4thedition 1987

[29] U Setzmann andWWagner ldquoA new equation of state and tablesof thermodynamic properties for methane covering the rangefrom the melting line to 625 K at pressures up to 100 MPardquoJournal of Physical and Chemical Reference Data vol 20 no 6p 1061 1991

[30] C R Zhang and S Y Yu The Test and Evaluation Methods ofCarbon Dioxide Gas Well Petroleum Industry Press BeijingChina 1999

[31] P Shen K Luo X Zheng et al ldquoExperimental study of near-critical behavior of rich gas condensate systemsrdquo in Proceedingsof the SPE Production and Operations Symposium SPE 67285Oklahoma City Okla USA March 2001

[32] Z J Lu H Tang C Q Li et al ldquoMaterial balance equationfor CO

2gas reservoir considering phase state changerdquo Xinjiang

Petroleum Geology vol 31 no 6 pp 617ndash620 2010[33] L N He Carbon Dioxide Chemistry Science Press Beijing

China 2013[34] S L Li Q Z Zhang X Q Ran et al Enhanced Oil Recovery

Technology by Gas Injection Sichuan Science and TechnologyPress Chengdu China 2001

[35] M Riva M Campestrini J Toubassy D Clodic and PStringari ldquoSolidndashliquidndashvapor equilibrium models for cryo-genic biogas upgradingrdquo Industrial amp Engineering ChemistryResearch vol 53 no 44 pp 17506ndash17514 2014

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Inorganic ChemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

International Journal ofPhotoenergy


Carbohydrate Chemistry

International Journal of


Journal of

Chemistry


Advances in

Physical Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2014

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

SpectroscopyInternational Journal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of


Chromatography Research International


Applied ChemistryJournal of



Theoretical ChemistryJournal of


Journal of

Spectroscopy

Analytical ChemistryInternational Journal of


Journal of


Quantum Chemistry


Organic Chemistry International

ElectrochemistryInternational Journal of



CatalystsJournal of


pressures critical temperatures and an integrated 119875-119879 phasediagram of different CO

2content natural gases are calculated

by using themodified PR equation of state andmodified 120572(119879)equation proposed by Saffari And the deviations between thesaturation pressure calculated by using the model proposedin this paper and experimental measured saturation pressureare analyzed Also revealed in this paper is the influenceof different CO

2content in natural gases on the 119875-119879 phase

diagrams and critical points Furthermore the variationlaw and affecting factors of the physical parameters suchas relative volume 119885-factor formation volume factor anddensity of high CO

2content natural gases are discussed in

this paper

2 Theories

By modifying the attractive term in the RedlickndashKwongequation of state Peng and Robinson were able to enhancethe model prediction of experimental data Since its incep-tion Peng-Robinson EOS has been widely used to estimatethermodynamic properties for hydrocarbon systems It reads[20 21] as

119875 =

119877119879

V minus 119887minus

119886 (119879)

V (V + 119887) + 119887 (V minus 119887) (1)

where 119875 is pressure 119879 is temperature V is the molar volume119877 is the gas constant and 119886(119879) and 119887 are the parameters of theEOS At constant119875 and119879 the equation will take the form of acubic equation in V and can be solved for V using any standardanalytical or numerical technique [22] The limitations oncritical point lead to the following relations for the PR-EOSparameters [20]

119886 (119879) = 119886 (119879119888) 120572 (119879)

119886 (119879119888) =

04572411987721198792

119888

119875119888

119887 = 00778

119877119879119888

119875119888

(2)

where subscript 119888 indicates critical property and 120572(119879) istemperature dependent In this work we use the new 120572-function proposed by Saffari which is written as [23]

120572 (119879) = exp [1198961119879119903+ 1198962ln119879119903+ 1198963(1 minus 119879

12

119903)] (3)

119879119903=

119879

119879119888

(4)

The new 120572-functions proposed are exponential functionseachwith three adjustable parameters 119896

1 1198962 and 119896

3 Since the

adjustable parameters determine attractive intermolecularinteractions in a pure component system the values of 119896

119894are

compound-specific and should be optimized for each purecomponent In this work we determine the optimum valuesof pure component parameters by minimizing the error ofvapor pressure predicted by using the modified PR equationof state and modified 120572(119879) equation proposed by Saffari with

0003

0004

0005

0006

0007

0008

0 01 02 03 04


y = 00113x + 00033

R2 = 09092

k1

120596


equation (3)

002

005

008

011

014

017

02

0 01 02 03 04minus001


y = 04106x + 00085

R2 = 06841

120596

k2


equation (3)

respect to the experimental values in the temperature rangefrom triple point to critical point [23]

Andweuse the individually optimized parameters of purecomponents for the new 120572-function proposed in this work(3) to develop generalized equations in terms of the acen-tric factor 120596 Pure component constants including criticalproperties and vapor pressure data are obtained from Polinget al [24] Yaws [25] and Smith and Srivastava [26] Theadjustable parameters of the new 120572-function proposed bySaffari have been fitted to experimental vapor pressure datagiven in Table 1

And then the parameters 1198961 1198962 and 119896

3are generalized

as a function of acentric factor 120596 Acentric factor of a purecomponent is obtained from Poling et al [24] Figures 1ndash3show the trend of fitted parameters presented inTable 1 versusthe acentric factor as well as a linear fit and the 119877-squared




1198961

1198962

1198963




119879119888

120596



120572 (119879) = exp [1198961119879119903+ 1198962ln119879119903+ 1198963(1 minus 119879

12

119903)]

1198961= 00113120596 + 00033

1198962= 04106120596 minus 00085

1198963= 3541120596 + 07532

(5)


119886 =

119899

sum

119894

119899

sum

119895

119909119894119909119895119886119894119895

119887 =

119899

sum

119895

119909119894119887119894

(6)





119886119894119895= (1 minus 119896

119894119895) (119886119894119886119895)

12

(7)

3 Experiments


2in YP9 well Gas1


2content in natural



05

08

11

14

17

2

0 01 02 03 04120596

k3

y = 3541x + 07532

R2 = 09656



equation (3)














2content [31]













2content





119875119905119881119905= 119899119877119885

119905119879119905 (8)


32

87

65

9

4

1






119905(cm3) 297 3951 3762 6676



0003496 0003481 0003257 0003091119885-factor119885

11990510702 10663 09885 09295

Gas density120588119905(kgm3) 23000 26851 39875 49413


11989206853 07763 10545 12398


119875sc119881sc = 119899119877119885sc119879sc (9)







120574119892=

119872

119872air (10)








2content natural


2content



000

100

200

300

400

500

600

0 10 20 30 40 50

Rela

tive v

olum

e

Pressure (MPa)

35∘C75∘C

1275∘C


0000

0005

0010

0015

0020

0025

0030

0 10 20 30 40 50

Form

atio

n vo

lum

e fac

tor

Pressure (MPa)

35∘C75∘C

1275∘C






2content

000

005

010

015

020

025

030

035

040

045

050

0 10 20 30 40 50Pressure (MPa)

35∘C75∘C

1275∘C

Gas

den

sity

(gc

m3)


070

080

090

100

110

0 10 20 30 40 50

Gas

com

pres

sibili

ty fa

ctor

Pressure (MPa)

35∘C75∘C1275∘C
















Calculatedvalue

Measuredvalue

Calculatedvalue

Measuredvalue

Calculatedvalue

Measuredvalue

Calculatedvalue

Measuredvalue


000

100

200

300

400

500

600

700

0 10 20 30 40 50

Rela

tive v

olum

e

Pressure (MPa)

Gas1YP9

Gas2Gas3



Gas1YP9

Gas2Gas3

000

001

001

002

002

003

0 10 20 30 40 50

Form

atio

n vo

lum

e fac

tor

Pressure (MPa)



000

010

020

030

040

050

060

0 10 20 30 40 50Pressure (MPa)

Gas

den

sity

(gc

m3)

Gas1YP9

Gas2Gas3






6has several











070

080

090

100

110

0 10 20 30 40 50

Gas

com

pres

sibili

ty fa

ctor

Pressure (MPa)

Gas1YP9

Gas2Gas3




2content


2


ARE () =119873

sum

119894=1

10038161003816100381610038161003816100381610038161003816

Cal minus ExpExp

10038161003816100381610038161003816100381610038161003816119894

times 100 (11)

AARE () = 1119873

119873

sum

119894=1

10038161003816100381610038161003816100381610038161003816

Cal minus ExpExp

10038161003816100381610038161003816100381610038161003816119894

times 100 (12)





4critical



4[35] Here we only


00102030405060708090

100

5 45

Pres

sure

(MPa

)


Temperature (∘C)



2contents

3

4

5

6

7

8

9

10

10 30

Pres

sure

(MPa

)


Temperature (∘C)

CH4(100)

CO2(10045)

CO2(55535) CO2(75323)

CO2(100)CO2(21746)


2contents






162

278

203

563

329

338 286








2is about 55535mol


2 the


4and CO



2content in natural
















5 Conclusions





Gas sample

Piston



medium

4234 37 32 25 21 19 16 13 10 5




Gas sample

Piston


medium

Phasetransition

20 18 654810121416







2content


2content










Acknowledgments


References
















2content






2-content



2content









2content offshore



2gas reservoirrdquo


































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of




1198961

1198962

1198963




119879119888

120596



120572 (119879) = exp [1198961119879119903+ 1198962ln119879119903+ 1198963(1 minus 119879

12

119903)]

1198961= 00113120596 + 00033

1198962= 04106120596 minus 00085

1198963= 3541120596 + 07532

(5)


119886 =

119899

sum

119894

119899

sum

119895

119909119894119909119895119886119894119895

119887 =

119899

sum

119895

119909119894119887119894

(6)





119886119894119895= (1 minus 119896

119894119895) (119886119894119886119895)

12

(7)

3 Experiments


2in YP9 well Gas1


2content in natural



05

08

11

14

17

2

0 01 02 03 04120596

k3

y = 3541x + 07532

R2 = 09656



equation (3)














2content [31]













2content





119875119905119881119905= 119899119877119885

119905119879119905 (8)


32

87

65

9

4

1






119905(cm3) 297 3951 3762 6676



0003496 0003481 0003257 0003091119885-factor119885

11990510702 10663 09885 09295

Gas density120588119905(kgm3) 23000 26851 39875 49413


11989206853 07763 10545 12398


119875sc119881sc = 119899119877119885sc119879sc (9)







120574119892=

119872

119872air (10)








2content natural


2content



000

100

200

300

400

500

600

0 10 20 30 40 50

Rela

tive v

olum

e

Pressure (MPa)

35∘C75∘C

1275∘C


0000

0005

0010

0015

0020

0025

0030

0 10 20 30 40 50

Form

atio

n vo

lum

e fac

tor

Pressure (MPa)

35∘C75∘C

1275∘C






2content

000

005

010

015

020

025

030

035

040

045

050

0 10 20 30 40 50Pressure (MPa)

35∘C75∘C

1275∘C

Gas

den

sity

(gc

m3)


070

080

090

100

110

0 10 20 30 40 50

Gas

com

pres

sibili

ty fa

ctor

Pressure (MPa)

35∘C75∘C1275∘C
















Calculatedvalue

Measuredvalue

Calculatedvalue

Measuredvalue

Calculatedvalue

Measuredvalue

Calculatedvalue

Measuredvalue


000

100

200

300

400

500

600

700

0 10 20 30 40 50

Rela

tive v

olum

e

Pressure (MPa)

Gas1YP9

Gas2Gas3



Gas1YP9

Gas2Gas3

000

001

001

002

002

003

0 10 20 30 40 50

Form

atio

n vo

lum

e fac

tor

Pressure (MPa)



000

010

020

030

040

050

060

0 10 20 30 40 50Pressure (MPa)

Gas

den

sity

(gc

m3)

Gas1YP9

Gas2Gas3






6has several











070

080

090

100

110

0 10 20 30 40 50

Gas

com

pres

sibili

ty fa

ctor

Pressure (MPa)

Gas1YP9

Gas2Gas3




2content


2


ARE () =119873

sum

119894=1

10038161003816100381610038161003816100381610038161003816

Cal minus ExpExp

10038161003816100381610038161003816100381610038161003816119894

times 100 (11)

AARE () = 1119873

119873

sum

119894=1

10038161003816100381610038161003816100381610038161003816

Cal minus ExpExp

10038161003816100381610038161003816100381610038161003816119894

times 100 (12)





4critical



4[35] Here we only


00102030405060708090

100

5 45

Pres

sure

(MPa

)


Temperature (∘C)



2contents

3

4

5

6

7

8

9

10

10 30

Pres

sure

(MPa

)


Temperature (∘C)

CH4(100)

CO2(10045)

CO2(55535) CO2(75323)

CO2(100)CO2(21746)


2contents






162

278

203

563

329

338 286








2is about 55535mol


2 the


4and CO



2content in natural
















5 Conclusions





Gas sample

Piston



medium

4234 37 32 25 21 19 16 13 10 5




Gas sample

Piston


medium

Phasetransition

20 18 654810121416







2content


2content










Acknowledgments


References
















2content






2-content



2content









2content offshore



2gas reservoirrdquo


































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


05

08

11

14

17

2

0 01 02 03 04120596

k3

y = 3541x + 07532

R2 = 09656



equation (3)














2content [31]













2content





119875119905119881119905= 119899119877119885

119905119879119905 (8)


32

87

65

9

4

1






119905(cm3) 297 3951 3762 6676



0003496 0003481 0003257 0003091119885-factor119885

11990510702 10663 09885 09295

Gas density120588119905(kgm3) 23000 26851 39875 49413


11989206853 07763 10545 12398


119875sc119881sc = 119899119877119885sc119879sc (9)







120574119892=

119872

119872air (10)








2content natural


2content



000

100

200

300

400

500

600

0 10 20 30 40 50

Rela

tive v

olum

e

Pressure (MPa)

35∘C75∘C

1275∘C


0000

0005

0010

0015

0020

0025

0030

0 10 20 30 40 50

Form

atio

n vo

lum

e fac

tor

Pressure (MPa)

35∘C75∘C

1275∘C






2content

000

005

010

015

020

025

030

035

040

045

050

0 10 20 30 40 50Pressure (MPa)

35∘C75∘C

1275∘C

Gas

den

sity

(gc

m3)


070

080

090

100

110

0 10 20 30 40 50

Gas

com

pres

sibili

ty fa

ctor

Pressure (MPa)

35∘C75∘C1275∘C
















Calculatedvalue

Measuredvalue

Calculatedvalue

Measuredvalue

Calculatedvalue

Measuredvalue

Calculatedvalue

Measuredvalue


000

100

200

300

400

500

600

700

0 10 20 30 40 50

Rela

tive v

olum

e

Pressure (MPa)

Gas1YP9

Gas2Gas3



Gas1YP9

Gas2Gas3

000

001

001

002

002

003

0 10 20 30 40 50

Form

atio

n vo

lum

e fac

tor

Pressure (MPa)



000

010

020

030

040

050

060

0 10 20 30 40 50Pressure (MPa)

Gas

den

sity

(gc

m3)

Gas1YP9

Gas2Gas3






6has several











070

080

090

100

110

0 10 20 30 40 50

Gas

com

pres

sibili

ty fa

ctor

Pressure (MPa)

Gas1YP9

Gas2Gas3




2content


2


ARE () =119873

sum

119894=1

10038161003816100381610038161003816100381610038161003816

Cal minus ExpExp

10038161003816100381610038161003816100381610038161003816119894

times 100 (11)

AARE () = 1119873

119873

sum

119894=1

10038161003816100381610038161003816100381610038161003816

Cal minus ExpExp

10038161003816100381610038161003816100381610038161003816119894

times 100 (12)





4critical



4[35] Here we only


00102030405060708090

100

5 45

Pres

sure

(MPa

)


Temperature (∘C)



2contents

3

4

5

6

7

8

9

10

10 30

Pres

sure

(MPa

)


Temperature (∘C)

CH4(100)

CO2(10045)

CO2(55535) CO2(75323)

CO2(100)CO2(21746)


2contents






162

278

203

563

329

338 286








2is about 55535mol


2 the


4and CO



2content in natural
















5 Conclusions





Gas sample

Piston



medium

4234 37 32 25 21 19 16 13 10 5




Gas sample

Piston


medium

Phasetransition

20 18 654810121416







2content


2content










Acknowledgments


References
















2content






2-content



2content









2content offshore



2gas reservoirrdquo


































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


32

87

65

9

4

1






119905(cm3) 297 3951 3762 6676



0003496 0003481 0003257 0003091119885-factor119885

11990510702 10663 09885 09295

Gas density120588119905(kgm3) 23000 26851 39875 49413


11989206853 07763 10545 12398


119875sc119881sc = 119899119877119885sc119879sc (9)







120574119892=

119872

119872air (10)








2content natural


2content



000

100

200

300

400

500

600

0 10 20 30 40 50

Rela

tive v

olum

e

Pressure (MPa)

35∘C75∘C

1275∘C


0000

0005

0010

0015

0020

0025

0030

0 10 20 30 40 50

Form

atio

n vo

lum

e fac

tor

Pressure (MPa)

35∘C75∘C

1275∘C






2content

000

005

010

015

020

025

030

035

040

045

050

0 10 20 30 40 50Pressure (MPa)

35∘C75∘C

1275∘C

Gas

den

sity

(gc

m3)


070

080

090

100

110

0 10 20 30 40 50

Gas

com

pres

sibili

ty fa

ctor

Pressure (MPa)

35∘C75∘C1275∘C
















Calculatedvalue

Measuredvalue

Calculatedvalue

Measuredvalue

Calculatedvalue

Measuredvalue

Calculatedvalue

Measuredvalue


000

100

200

300

400

500

600

700

0 10 20 30 40 50

Rela

tive v

olum

e

Pressure (MPa)

Gas1YP9

Gas2Gas3



Gas1YP9

Gas2Gas3

000

001

001

002

002

003

0 10 20 30 40 50

Form

atio

n vo

lum

e fac

tor

Pressure (MPa)



000

010

020

030

040

050

060

0 10 20 30 40 50Pressure (MPa)

Gas

den

sity

(gc

m3)

Gas1YP9

Gas2Gas3






6has several











070

080

090

100

110

0 10 20 30 40 50

Gas

com

pres

sibili

ty fa

ctor

Pressure (MPa)

Gas1YP9

Gas2Gas3




2content


2


ARE () =119873

sum

119894=1

10038161003816100381610038161003816100381610038161003816

Cal minus ExpExp

10038161003816100381610038161003816100381610038161003816119894

times 100 (11)

AARE () = 1119873

119873

sum

119894=1

10038161003816100381610038161003816100381610038161003816

Cal minus ExpExp

10038161003816100381610038161003816100381610038161003816119894

times 100 (12)





4critical



4[35] Here we only


00102030405060708090

100

5 45

Pres

sure

(MPa

)


Temperature (∘C)



2contents

3

4

5

6

7

8

9

10

10 30

Pres

sure

(MPa

)


Temperature (∘C)

CH4(100)

CO2(10045)

CO2(55535) CO2(75323)

CO2(100)CO2(21746)


2contents






162

278

203

563

329

338 286








2is about 55535mol


2 the


4and CO



2content in natural
















5 Conclusions





Gas sample

Piston



medium

4234 37 32 25 21 19 16 13 10 5




Gas sample

Piston


medium

Phasetransition

20 18 654810121416







2content


2content










Acknowledgments


References
















2content






2-content



2content









2content offshore



2gas reservoirrdquo


































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


000

100

200

300

400

500

600

0 10 20 30 40 50

Rela

tive v

olum

e

Pressure (MPa)

35∘C75∘C

1275∘C


0000

0005

0010

0015

0020

0025

0030

0 10 20 30 40 50

Form

atio

n vo

lum

e fac

tor

Pressure (MPa)

35∘C75∘C

1275∘C






2content

000

005

010

015

020

025

030

035

040

045

050

0 10 20 30 40 50Pressure (MPa)

35∘C75∘C

1275∘C

Gas

den

sity

(gc

m3)


070

080

090

100

110

0 10 20 30 40 50

Gas

com

pres

sibili

ty fa

ctor

Pressure (MPa)

35∘C75∘C1275∘C
















Calculatedvalue

Measuredvalue

Calculatedvalue

Measuredvalue

Calculatedvalue

Measuredvalue

Calculatedvalue

Measuredvalue


000

100

200

300

400

500

600

700

0 10 20 30 40 50

Rela

tive v

olum

e

Pressure (MPa)

Gas1YP9

Gas2Gas3



Gas1YP9

Gas2Gas3

000

001

001

002

002

003

0 10 20 30 40 50

Form

atio

n vo

lum

e fac

tor

Pressure (MPa)



000

010

020

030

040

050

060

0 10 20 30 40 50Pressure (MPa)

Gas

den

sity

(gc

m3)

Gas1YP9

Gas2Gas3






6has several











070

080

090

100

110

0 10 20 30 40 50

Gas

com

pres

sibili

ty fa

ctor

Pressure (MPa)

Gas1YP9

Gas2Gas3




2content


2


ARE () =119873

sum

119894=1

10038161003816100381610038161003816100381610038161003816

Cal minus ExpExp

10038161003816100381610038161003816100381610038161003816119894

times 100 (11)

AARE () = 1119873

119873

sum

119894=1

10038161003816100381610038161003816100381610038161003816

Cal minus ExpExp

10038161003816100381610038161003816100381610038161003816119894

times 100 (12)





4critical



4[35] Here we only


00102030405060708090

100

5 45

Pres

sure

(MPa

)


Temperature (∘C)



2contents

3

4

5

6

7

8

9

10

10 30

Pres

sure

(MPa

)


Temperature (∘C)

CH4(100)

CO2(10045)

CO2(55535) CO2(75323)

CO2(100)CO2(21746)


2contents






162

278

203

563

329

338 286








2is about 55535mol


2 the


4and CO



2content in natural
















5 Conclusions





Gas sample

Piston



medium

4234 37 32 25 21 19 16 13 10 5




Gas sample

Piston


medium

Phasetransition

20 18 654810121416







2content


2content










Acknowledgments


References
















2content






2-content



2content









2content offshore



2gas reservoirrdquo


































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of




Calculatedvalue

Measuredvalue

Calculatedvalue

Measuredvalue

Calculatedvalue

Measuredvalue

Calculatedvalue

Measuredvalue


000

100

200

300

400

500

600

700

0 10 20 30 40 50

Rela

tive v

olum

e

Pressure (MPa)

Gas1YP9

Gas2Gas3



Gas1YP9

Gas2Gas3

000

001

001

002

002

003

0 10 20 30 40 50

Form

atio

n vo

lum

e fac

tor

Pressure (MPa)



000

010

020

030

040

050

060

0 10 20 30 40 50Pressure (MPa)

Gas

den

sity

(gc

m3)

Gas1YP9

Gas2Gas3






6has several











070

080

090

100

110

0 10 20 30 40 50

Gas

com

pres

sibili

ty fa

ctor

Pressure (MPa)

Gas1YP9

Gas2Gas3




2content


2


ARE () =119873

sum

119894=1

10038161003816100381610038161003816100381610038161003816

Cal minus ExpExp

10038161003816100381610038161003816100381610038161003816119894

times 100 (11)

AARE () = 1119873

119873

sum

119894=1

10038161003816100381610038161003816100381610038161003816

Cal minus ExpExp

10038161003816100381610038161003816100381610038161003816119894

times 100 (12)





4critical



4[35] Here we only


00102030405060708090

100

5 45

Pres

sure

(MPa

)


Temperature (∘C)



2contents

3

4

5

6

7

8

9

10

10 30

Pres

sure

(MPa

)


Temperature (∘C)

CH4(100)

CO2(10045)

CO2(55535) CO2(75323)

CO2(100)CO2(21746)


2contents






162

278

203

563

329

338 286








2is about 55535mol


2 the


4and CO



2content in natural
















5 Conclusions





Gas sample

Piston



medium

4234 37 32 25 21 19 16 13 10 5




Gas sample

Piston


medium

Phasetransition

20 18 654810121416







2content


2content










Acknowledgments


References
















2content






2-content



2content









2content offshore



2gas reservoirrdquo


































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


070

080

090

100

110

0 10 20 30 40 50

Gas

com

pres

sibili

ty fa

ctor

Pressure (MPa)

Gas1YP9

Gas2Gas3




2content


2


ARE () =119873

sum

119894=1

10038161003816100381610038161003816100381610038161003816

Cal minus ExpExp

10038161003816100381610038161003816100381610038161003816119894

times 100 (11)

AARE () = 1119873

119873

sum

119894=1

10038161003816100381610038161003816100381610038161003816

Cal minus ExpExp

10038161003816100381610038161003816100381610038161003816119894

times 100 (12)





4critical



4[35] Here we only


00102030405060708090

100

5 45

Pres

sure

(MPa

)


Temperature (∘C)



2contents

3

4

5

6

7

8

9

10

10 30

Pres

sure

(MPa

)


Temperature (∘C)

CH4(100)

CO2(10045)

CO2(55535) CO2(75323)

CO2(100)CO2(21746)


2contents






162

278

203

563

329

338 286








2is about 55535mol


2 the


4and CO



2content in natural
















5 Conclusions





Gas sample

Piston



medium

4234 37 32 25 21 19 16 13 10 5




Gas sample

Piston


medium

Phasetransition

20 18 654810121416







2content


2content










Acknowledgments


References
















2content






2-content



2content









2content offshore



2gas reservoirrdquo


































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of





162

278

203

563

329

338 286








2is about 55535mol


2 the


4and CO



2content in natural
















5 Conclusions





Gas sample

Piston



medium

4234 37 32 25 21 19 16 13 10 5




Gas sample

Piston


medium

Phasetransition

20 18 654810121416







2content


2content










Acknowledgments


References
















2content






2-content



2content









2content offshore



2gas reservoirrdquo


































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


Gas sample

Piston



medium

4234 37 32 25 21 19 16 13 10 5




Gas sample

Piston


medium

Phasetransition

20 18 654810121416







2content


2content










Acknowledgments


References
















2content






2-content



2content









2content offshore



2gas reservoirrdquo


































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of





2-content



2content









2content offshore



2gas reservoirrdquo


































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of










Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of

Documents

Research Article Phase Behavior and Physical Parameters of ...downloads.hindawi.com/journals/jchem/2015/873718.pdf · ( ) Two- ash experiments and CCE experiments were also performed