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Difference between revisions of "Calculating PVT properties"

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This is an example of calculating PVT properties. The specific correlations that should be used for a specific crude oil or reservoir may vary, as discussed in the referenced pages focusing on specific properties.
+
This is an example of calculating PVT properties. The specific correlations that should be used for a specific crude oil or reservoir may vary, as discussed in the referenced pages focusing on specific properties.
  
Determine the PVT properties for a United States midcontinental crude oil and natural gas system with properties listed in '''Table 1'''. '''Table 2''' lists the correlations to be used. Measured data are provided for comparison with the calculated results. For correlations that rely on other correlations, these data illustrate the effects of error propagation in the calculations.  
+
Determine the PVT properties for a United States midcontinental crude oil and natural gas system with properties listed in '''Table 1'''. '''Table 2''' lists the correlations to be used. Measured data are provided for comparison with the calculated results. For correlations that rely on other correlations, these data illustrate the effects of error propagation in the calculations.
  
<gallery widths=300px heights=200px>
+
<gallery widths="300px" heights="200px">
 
File:vol1 Page 302 Image 0002.png|'''Table 1'''
 
File:vol1 Page 302 Image 0002.png|'''Table 1'''
  
Line 9: Line 9:
 
</gallery>
 
</gallery>
  
==Gravity and molecular weight==
+
== Gravity and molecular weight ==
Determine the [[Crude oil characterization|crude oil specific gravity]],
 
  
[[File:Vol1 page 0291 eq 002.png]]....................(1)
+
Determine the [[Crude_oil_characterization|crude oil specific gravity]],
 +
 
 +
[[File:Vol1 page 0291 eq 002.png|RTENOTITLE]]....................(1)
  
 
and molecular weight,
 
and molecular weight,
  
[[File:Vol1 page 0292 eq 001.png]]....................(2)
+
[[File:Vol1 page 0292 eq 001.png|RTENOTITLE]]....................(2)
  
==Bubblepoint pressure==
+
== Bubblepoint pressure ==
Use the Lasater<ref name="r1" /> correlation to estimate [[Oil bubblepoint pressure|bubblepoint pressure]]. Calculate the gas mole fraction in the oil,
 
  
[[File:Vol1 page 0292 eq 002.png]]....................(3)
+
Use the Lasater<ref name="r1">Lasater, J.A. 1958. Bubble Point Pressure Correlations. J Pet Technol 10 (5): 65–67. SPE-957-G. http://dx.doi.org/10.2118/957-G.</ref> correlation to estimate [[Oil_bubblepoint_pressure|bubblepoint pressure]]. Calculate the gas mole fraction in the oil,
 +
 
 +
[[File:Vol1 page 0292 eq 002.png|RTENOTITLE]]....................(3)
  
 
and the Lasater bubblepoint pressure factor,
 
and the Lasater bubblepoint pressure factor,
  
[[File:Vol1 page 0292 eq 003.png]]....................(4)
+
[[File:Vol1 page 0292 eq 003.png|RTENOTITLE]]....................(4)
  
 
with Lasater’s relationship between bubblepoint pressure factor and bubblepoint pressure,
 
with Lasater’s relationship between bubblepoint pressure factor and bubblepoint pressure,
  
[[File:Vol1 page 0292 eq 004.png]]....................(5)
+
[[File:Vol1 page 0292 eq 004.png|RTENOTITLE]]....................(5)
  
For comparison, Standing<ref name="r2" /><ref name="r3" /> = 2,316 psia, Glasø<ref name="r4" /> = 2,725 psia, Al-Shammasi<ref name="r5" /> = 2,421 psia, and Velardi<ref name="r6" /> = 2,411 psia.  
+
For comparison, Standing<ref name="r2">Standing, M.B. 1981. Volumetric and Phase Behavior of Oil Field Hydrocarbon Systems, ninth edition. Richardson, Texas: Society of Petroleum Engineers of AIME</ref><ref name="r3">Standing, M.B. 1947. A Pressure-Volume-Temperature Correlation for Mixtures of California Oils and Gases. API Drilling and Production Practice (1947): 275-287.</ref> = 2,316 psia, Glasø<ref name="r4">Glasø, Ø. 1980. Generalized Pressure-Volume-Temperature Correlations. J Pet Technol 32 (5): 785-795. SPE-8016-PA. http://dx.doi.org/10.2118/8016-PA</ref> = 2,725 psia, Al-Shammasi<ref name="r5">Al-Shammasi, A.A. 2001. A Review of Bubblepoint Pressure and Oil Formation Volume Factor Correlations. SPE Res Eval & Eng 4 (2): 146-160. SPE-71302-PA. http://dx.doi.org/10.2118/71302-PA</ref> = 2,421 psia, and Velardi<ref name="r6">Velarde, J., Blasingame, T.A., and McCain Jr., W.D. 1997. Correlation of Black Oil Properties At Pressures Below Bubble Point Pressure - A New Approach. Presented at the Annual Technical Meeting of CIM, Calgary, Alberta, 8–11 June. PETSOC-97-93. http://dx.doi.org/10.2118/97-93</ref> = 2,411 psia.
  
 
Modify the calculated bubblepoint pressure to account for the effects of nitrogen in the surface gas with Jacobson’s equation.
 
Modify the calculated bubblepoint pressure to account for the effects of nitrogen in the surface gas with Jacobson’s equation.
  
[[File:Vol1 page 0293 eq 001.png]]....................(6)
+
[[File:Vol1 page 0293 eq 001.png|RTENOTITLE]]....................(6)
  
 
Therefore, the bubblepoint pressure should be increased by 9.8% to 2,251 psia. The measured bubblepoint pressure was reported to be 2,479 psia.
 
Therefore, the bubblepoint pressure should be increased by 9.8% to 2,251 psia. The measured bubblepoint pressure was reported to be 2,479 psia.
  
==Bubblepoint oil formation volume factor==
+
== Bubblepoint oil formation volume factor ==
Calculate the bubblepoint oil [[Oil formation volume factor|formation volume factor]] (FVF) using the correlation from Al-Shammasi.<ref name="r5" />
+
 
 +
Calculate the bubblepoint oil [[Oil_formation_volume_factor|formation volume factor]] (FVF) using the correlation from Al-Shammasi.<ref name="r5">Al-Shammasi, A.A. 2001. A Review of Bubblepoint Pressure and Oil Formation Volume Factor Correlations. SPE Res Eval & Eng 4 (2): 146-160. SPE-71302-PA. http://dx.doi.org/10.2118/71302-PA</ref>
 +
 
 +
[[File:Vol1 page 0293 eq 002.png|RTENOTITLE]]....................(7)
 +
 
 +
[[File:Vol1 page 0293 eq 003.png|RTENOTITLE]]
 +
 
 +
For comparison (in bbl/STB), Standing<ref name="r2">Standing, M.B. 1981. Volumetric and Phase Behavior of Oil Field Hydrocarbon Systems, ninth edition. Richardson, Texas: Society of Petroleum Engineers of AIME</ref><ref name="r3">Standing, M.B. 1947. A Pressure-Volume-Temperature Correlation for Mixtures of California Oils and Gases. API Drilling and Production Practice (1947): 275-287.</ref> = 1.410, Glasø<ref name="r4">Glasø, Ø. 1980. Generalized Pressure-Volume-Temperature Correlations. J Pet Technol 32 (5): 785-795. SPE-8016-PA. http://dx.doi.org/10.2118/8016-PA</ref> = 1.386, Al-Marhoun<ref name="r7">Al-Marhoun, M.A. 1992. New Correlations For Formation Volume Factors Of Oil And Gas Mixtures. J Can Pet Technol 31 (3): 22. PETSOC-92-03-02. http://dx.doi.org/10.2118/92-03-02</ref> = 1.364, Farshad<ref name="r8">Frashad, F., LeBlanc, J.L., Garber, J.D. et al. 1996. Empirical PVT Correlations For Colombian Crude Oils. Presented at the SPE Latin American and Caribbean Petroleum Engineering Conference, Port of Spain, Trinidad and Tobago, 23–26 April. SPE-36105-MS. http://dx.doi.org/10.2118/36105-MS</ref> = 1.364, and Kartoatmodjo<ref name="r9">Kartoatmodjo, R.S.T. 1990. New Correlations for Estimating Hydrocarbon Liquid Properties. MS thesis, University of Tulsa, Tulsa, Oklahoma.</ref><ref name="r10">Kartoatmodjo, T.R.S. and Schmidt, Z. 1991. New Correlations for Crude Oil Physical Properties, Society of Petroleum Engineers, unsolicited paper 23556-MS.</ref><ref name="r11">Kartoatmodjo, T. and Z., S. 1994. Large Data Bank Improves Crude Physical Property Correlations. Oil Gas J. 92 (27): 51–55.</ref> = 1.358. The measured bubblepoint oil FVF is 1.398 bbl/STB.
 +
 
 +
== Isothermal compressibility ==
 +
 
 +
Calculate the [[Isothermal_compressibility_of_oil|isothermal compressibility of oil]] using the Farshad<ref name="r8">Frashad, F., LeBlanc, J.L., Garber, J.D. et al. 1996. Empirical PVT Correlations For Colombian Crude Oils. Presented at the SPE Latin American and Caribbean Petroleum Engineering Conference, Port of Spain, Trinidad and Tobago, 23–26 April. SPE-36105-MS. http://dx.doi.org/10.2118/36105-MS</ref> correlation.
 +
 
 +
[[File:Vol1 page 0294 eq 001.png|RTENOTITLE]]....................(8)
 +
 
 +
[[File:Vol1 page 0294 eq 002.png|RTENOTITLE]]....................(9)
  
[[File:Vol1 page 0293 eq 002.png]]....................(7)
+
[[File:Vol1 page 0294 eq 003.png|RTENOTITLE]]
  
[[File:Vol1 page 0293 eq 003.png]]
+
The measured isothermal compressibility is 11.06 × 10<sup>-6</sup>psi<sup>-1</sup>.
  
For comparison (in bbl/STB), Standing<ref name="r2" /><ref name="r3" /> = 1.410, Glasø<ref name="r4" /> = 1.386, Al-Marhoun<ref name="r7"/> = 1.364, Farshad<ref name="r8" /> = 1.364, and Kartoatmodjo<ref name="r9" /><ref name="r10" /><ref name="r11" /> = 1.358. The measured bubblepoint oil FVF is 1.398 bbl/STB.
+
== Undersaturated oil formation volume factor ==
  
==Isothermal compressibility==
+
With the results from Lasater’s<ref name="r1">Lasater, J.A. 1958. Bubble Point Pressure Correlations. J Pet Technol 10 (5): 65–67. SPE-957-G. http://dx.doi.org/10.2118/957-G.</ref> method for bubblepoint pressure, use Al-Shammasi’s<ref name="r5">Al-Shammasi, A.A. 2001. A Review of Bubblepoint Pressure and Oil Formation Volume Factor Correlations. SPE Res Eval & Eng 4 (2): 146-160. SPE-71302-PA. http://dx.doi.org/10.2118/71302-PA</ref> method for bubblepoint oil FVF, and Farshad’s<ref name="r8">Frashad, F., LeBlanc, J.L., Garber, J.D. et al. 1996. Empirical PVT Correlations For Colombian Crude Oils. Presented at the SPE Latin American and Caribbean Petroleum Engineering Conference, Port of Spain, Trinidad and Tobago, 23–26 April. SPE-36105-MS. http://dx.doi.org/10.2118/36105-MS</ref> equation for isothermal compressibility, the undersaturated oil FVF is given by
Calculate the [[isothermal compressibility of oil]] using the Farshad<ref name="r8" /> correlation.
 
  
[[File:Vol1 page 0294 eq 001.png]]....................(8)
+
[[File:Vol1 page 0294 eq 004.png|RTENOTITLE]]....................(10)
  
[[File:Vol1 page 0294 eq 002.png]]....................(9)
+
[[File:Vol1 page 0294 eq 005.png|RTENOTITLE]]
  
[[File:Vol1 page 0294 eq 003.png]]
+
which compares to a measured value of 1.367 bbl/STB. Because this calculation uses the results from multiple correlations, individual correlation error compounds and propagates through to the final result. The calculated value is 1.367 bbl/STB with the actual bubblepoint value of 1.398 bbl/STB; therefore, the accuracy of the bubblepoint FVF is primarily affected by the accuracy of the undersaturated FVF.
  
The measured isothermal compressibility is 11.06 × 10<sup>-6</sup>psi<sup>-1</sup>.
+
== Oil density ==
  
==Undersaturated oil formation volume factor==
+
Calculate the [[Oil_density|oil density]].
With the results from Lasater’s<ref name="r1" /> method for bubblepoint pressure, use Al-Shammasi’s<ref name="r5" /> method for bubblepoint oil FVF, and Farshad’s<ref name="r8" /> equation for isothermal compressibility, the undersaturated oil FVF is given by
 
  
[[File:Vol1 page 0294 eq 004.png]]....................(10)
+
[[File:Vol1 page 0295 eq 001.png|RTENOTITLE]]....................(11)
  
[[File:Vol1 page 0294 eq 005.png]]
+
== Dead oil viscosity ==
  
which compares to a measured value of 1.367 bbl/STB. Because this calculation uses the results from multiple correlations, individual correlation error compounds and propagates through to the final result. The calculated value is 1.367 bbl/STB with the actual bubblepoint value of 1.398 bbl/STB; therefore, the accuracy of the bubblepoint FVF is primarily affected by the accuracy of the undersaturated FVF.  
+
Calculate the dead [[Oil_viscosity|oil viscosity]] using the correlation from Glasø.<ref name="r4">Glasø, Ø. 1980. Generalized Pressure-Volume-Temperature Correlations. J Pet Technol 32 (5): 785-795. SPE-8016-PA. http://dx.doi.org/10.2118/8016-PA</ref>
  
==Oil density==
+
[[File:Vol1 page 0295 eq 002.png|RTENOTITLE]]....................(12)
Calculate the [[oil density]].
 
  
[[File:Vol1 page 0295 eq 001.png]]....................(11)
+
For comparison, Fitzgerald<ref name="r12">Fitzgerald, D.J. 1994. A Predictive Method for Estimating the Viscosity of Undefined Hydrocarbon Liquid Mixtures. MS thesis, Pennsylvania State University, State College, Pennsylvania.</ref><ref name="r13">Daubert, T.E. and Danner, R.P. 1997. API Technical Data Book—Petroleum Refining, 6th edition, Chap. 11. Washington, DC: American Petroleum Institute (API).</ref><ref name="r14">Sutton, R.P. and Farshad, F. 1990. Evaluation of Empirically Derived PVT Properties for Gulf of Mexico Crude Oils. SPE Res Eng 5 (1): 79-86. SPE-13172-PA. http://dx.doi.org/10.2118/13172-PA</ref> = 1.808 cp, and Bergman<ref name="r15">Whitson, C.H. and Brulé, M.R. 2000. Phase Behavior, No. 20, Chap. 3. Richardson, Texas: Henry L. Doherty Monograph Series, Society of Petroleum Engineers.</ref><ref name="r16">Bergman, D.F. 2004. Don’t Forget Viscosity. Presented at the Petroleum Technology Transfer Council 2nd Annual Reservoir Engineering Symposium, Lafayette, Louisiana, 28 July.</ref> = 2.851 cp. The measured dead oil viscosity is 1.67 cp.
  
==Dead oil viscosity==
+
== Bubblepoint oil viscosity ==
Calculate the dead [[oil viscosity]] using the correlation from Glasø.<ref name="r4" />
 
  
[[File:Vol1 page 0295 eq 002.png]]....................(12)
+
Calculate the bubblepoint [[Oil_viscosity|oil viscosity]] using the method developed by Chew and Connally.<ref name="r17">Chew, J. and Connally, C.A. Jr. 1959. A Viscosity Correlation for Gas-Saturated Crude Oils. In Transactions of the American Institute of Mining, Metallurgical, and Petroleum Engineers, Vol. 216, 23. Dallas, Texas: Society of Petroleum Engineers of AIME.</ref><ref name="r18">Aziz, K. and Govier, G.W. 1972. Pressure Drop in Wells Producing Oil and Gas. J Can Pet Technol 11 (3): 38. PETSOC-72-03-04. http://dx.doi.org/10.2118/72-03-04</ref>
  
For comparison, Fitzgerald<ref name="r12" /><ref name="r13" /><ref name="r14" /> = 1.808 cp, and Bergman<ref name="r15" /><ref name="r16" /> = 2.851 cp. The measured dead oil viscosity is 1.67 cp.  
+
[[File:Vol1 page 0295 eq 003.png|RTENOTITLE]]....................(13)
  
==Bubblepoint oil viscosity==
+
[[File:Vol1 page 0296 eq 001.png|RTENOTITLE]]....................(14)
Calculate the bubblepoint [[oil viscosity]] using the method developed by Chew and Connally.<ref name="r17" /><ref name="r18" />
 
  
[[File:Vol1 page 0295 eq 003.png]]....................(13)
+
[[File:Vol1 page 0296 eq 002.png|RTENOTITLE]]....................(15)
  
[[File:Vol1 page 0296 eq 001.png]]....................(14)
+
For comparison, Beggs and Robinson<ref name="r19">Beggs, H.D. and Robinson, J.R. 1975. Estimating the Viscosity of Crude Oil Systems. J Pet Technol 27 (9): 1140-1141. SPE-5434-PA. http://dx.doi.org/10.2118/5434-PA</ref> = 0.515 cp. The measured viscosity at bubblepoint is 0.401 cp.
  
[[File:Vol1 page 0296 eq 002.png]]....................(15)
+
== Undersaturated oil viscosity ==
  
For comparison, Beggs and Robinson<ref name="r19" /> = 0.515 cp. The measured viscosity at bubblepoint is 0.401 cp.
+
Calculate the undersaturated oil viscosity by applying the Vazquez and Beggs<ref name="r20">Vazquez, M.E. 1976. Correlations for Fluid Physical Property Prediction. MS thesis, University of Tulsa, Tulsa, Oklahoma.</ref><ref name="r21">Vazquez, M. and Beggs, H.D. 1980. Correlations for Fluid Physical Property Prediction. J Pet Technol 32 (6): 968-970. SPE-6719-PA. http://dx.doi.org/10.2118/6719-PA</ref> correlation.
  
==Undersaturated oil viscosity==
+
[[File:Vol1 page 0296 eq 003.png|RTENOTITLE]]....................(16)
Calculate the undersaturated oil viscosity by applying the Vazquez and Beggs<ref name="r20" /><ref name="r21" /> correlation.
 
  
[[File:Vol1 page 0296 eq 003.png]]....................(16)
+
[[File:Vol1 page 0296 eq 004.png|RTENOTITLE]]
  
[[File:Vol1 page 0296 eq 004.png]]
+
For comparison, Beal<ref name="r22">Beal, C. 1970. The Viscosity of Air, Water, Natural Gas, Crude Oil and Its Associated Gases at Oil Field Temperatures and Pressures, No. 3, 114–127. Richardson, Texas: Reprint Series (Oil and Gas Property Evaluation and Reserve Estimates), SPE.</ref> = 0.730 cp and Kouzel<ref name="r23">Kouzel, B. 1965. How Pressure Affects Liquid Viscosity. Hydrocarb. Process. (March 1965): 120.</ref> = 0.778 cp. The measured value is 0.475 cp. This example illustrates the steps necessary to calculate oil viscosity requiring correlations for dead oil viscosity, bubblepoint viscosity, undersaturated viscosity, and bubblepoint pressure/solution GOR. Errors in individual correlations can compound and propagate through to the resulting answer. For instance, if the measured bubblepoint viscosity is used in '''Eq. 16''', the result is 0.52 cp—much closer to the measured value. Therefore, care should be exercised in the selection of accurate correlations for individual properties.
  
For comparison, Beal<ref name="r22" /> = 0.730 cp and Kouzel<ref name="r23" /> = 0.778 cp. The measured value is 0.475 cp. This example illustrates the steps necessary to calculate oil viscosity requiring correlations for dead oil viscosity, bubblepoint viscosity, undersaturated viscosity, and bubblepoint pressure/solution GOR. Errors in individual correlations can compound and propagate through to the resulting answer. For instance, if the measured bubblepoint viscosity is used in '''Eq. 16''', the result is 0.52 cp—much closer to the measured value. Therefore, care should be exercised in the selection of accurate correlations for individual properties.
+
== Gas/oil interfacial tension ==
  
==Gas/oil interfacial tension==
+
Estimate the [[Interfacial_tension|gas/oil surface tension]] using the method developed by Abdul-Majeed.<ref name="r24">Abdul-Majeed, G.H. and Abu Al-Soof, N.B. 2000. Estimation of gas–oil surface tension. J. Pet. Sci. Eng. 27 (3–4): 197-200. http://dx.doi.org/10.1016/S0920-4105(00)00058-9</ref> Calculate the dead oil surface tension.
Estimate the [[Interfacial tension|gas/oil surface tension]] using the method developed by Abdul-Majeed.<ref name="r24" /> Calculate the dead oil surface tension.
 
  
[[File:Vol1 page 0297 eq 001.png]]....................(17)
+
[[File:Vol1 page 0297 eq 001.png|RTENOTITLE]]....................(17)
  
[[File:Vol1 page 0297 eq 002.png]]
+
[[File:Vol1 page 0297 eq 002.png|RTENOTITLE]]
  
 
Determine the live oil adjustment factor.
 
Determine the live oil adjustment factor.
  
[[File:Vol1 page 0297 eq 003.png]]....................(18)
+
[[File:Vol1 page 0297 eq 003.png|RTENOTITLE]]....................(18)
  
[[File:Vol1 page 0297 eq 004.png]]
+
[[File:Vol1 page 0297 eq 004.png|RTENOTITLE]]
  
 
Calculate the live gas/oil surface tension.
 
Calculate the live gas/oil surface tension.
  
[[File:Vol1 page 0297 eq 005.png]]....................(19)
+
[[File:Vol1 page 0297 eq 005.png|RTENOTITLE]]....................(19)
  
[[File:Vol1 page 0298 eq 001.png]]
+
[[File:Vol1 page 0298 eq 001.png|RTENOTITLE]]
  
For comparison, Baker and Swerdloff<ref name="r25" /><ref name="r26" /> = 4.73 dynes/cm.  
+
For comparison, Baker and Swerdloff<ref name="r25">Baker, O. and Swerdloff, W. 1955. Calculation of Surface Tension 3—Calculating parachor Values. Oil Gas J. (5 December 1955): 141.</ref><ref name="r26">Baker, O. and Swerdloff, W. 1956. Calculation of Surface Tension 6—Finding Surface Tension of Hydrocarbon Liquids. Oil Gas J. (2 January 1956): 125.</ref> = 4.73 dynes/cm.
  
==Water/oil interfacial tension==
+
== Water/oil interfacial tension ==
Estimate the water/oil [[Interfacial tension|surface tension]] using Firoozabadi and Ramey.<ref name="r27" /> Calculate the pseudocritical temperature of the dead oil.
 
  
[[File:Vol1 page 0298 eq 002.png]]....................(20)
+
Estimate the water/oil [[Interfacial_tension|surface tension]] using Firoozabadi and Ramey.<ref name="r27">Firoozabadi, A. and Ramey Jr., H.J. 1988. Surface Tension of Water-Hydrocarbon Systems at Reservoir Conditions. J Can Pet Technol 27 (May–June): 41–48.</ref> Calculate the pseudocritical temperature of the dead oil.
  
[[File:Vol1 page 0298 eq 003.png]]
+
[[File:Vol1 page 0298 eq 002.png|RTENOTITLE]]....................(20)
 +
 
 +
[[File:Vol1 page 0298 eq 003.png|RTENOTITLE]]
  
 
Calculate the pseudocritical temperature of the gas.
 
Calculate the pseudocritical temperature of the gas.
  
[[File:Vol1 page 0298 eq 004.png]]....................(21)
+
[[File:Vol1 page 0298 eq 004.png|RTENOTITLE]]....................(21)
  
[[File:Vol1 page 0298 eq 005.png]]
+
[[File:Vol1 page 0298 eq 005.png|RTENOTITLE]]
  
 
Calculate the pseudocritical temperature of the live gas/oil mixture.
 
Calculate the pseudocritical temperature of the live gas/oil mixture.
  
[[File:Vol1 page 0298 eq 006.png]]....................(22)
+
[[File:Vol1 page 0298 eq 006.png|RTENOTITLE]]....................(22)
  
 
Convert oil density units from lbm/ft<sup>3</sup> to g/cm<sup>3</sup>.
 
Convert oil density units from lbm/ft<sup>3</sup> to g/cm<sup>3</sup>.
  
[[File:Vol1 page 0300 eq 001.png]]....................(23)
+
[[File:Vol1 page 0300 eq 001.png|RTENOTITLE]]....................(23)
  
 
Calculate the surface tension between the oil and water phases.
 
Calculate the surface tension between the oil and water phases.
  
[[File:Vol1 page 0300 eq 002.png]]....................(24)
+
[[File:Vol1 page 0300 eq 002.png|RTENOTITLE]]....................(24)
  
[[File:Vol1 page 0300 eq 003.png]]
+
[[File:Vol1 page 0300 eq 003.png|RTENOTITLE]]
 +
 
 +
== Nomenclature ==
  
==Nomenclature==
 
 
{|
 
{|
|''B''<sub>''g''</sub>
 
|=
 
|gas FVF, ft<sup>3</sup>/scf
 
 
|-
 
|-
|''B''<sub>''o''</sub>  
+
| ''B''<sub>''g''</sub>
|=  
+
| =
|oil FVF, bbl/STB
+
| gas FVF, ft<sup>3</sup>/scf
 
|-
 
|-
|''B''<sub>''ob''</sub>  
+
| ''B''<sub>''o''</sub>
|=  
+
| =
|oil formation volume at bubblepoint pressure, bbl/STB  
+
| oil FVF, bbl/STB
 
|-
 
|-
|''c''<sub>''o''</sub>  
+
| ''B''<sub>''ob''</sub>
|=  
+
| =
|oil isothermal compressibility, Lt<sup>2</sup>/m, psi<sup>-1</sup>
+
| oil formation volume at bubblepoint pressure, bbl/STB
 
|-
 
|-
|''c''<sub>''ob''</sub>  
+
| ''c''<sub>''o''</sub>
|=  
+
| =
|oil isothermal compressibility at bubblepoint, Lt<sup>2</sup>/m, psi<sup>-1</sup>  
+
| oil isothermal compressibility, Lt<sup>2</sup>/m, psi<sup>-1</sup>
 
|-
 
|-
|''K''<sub>''w''</sub>  
+
| ''c''<sub>''ob''</sub>
|=  
+
| =
|Watson characterization factor, °R<sup>1/3</sup>  
+
| oil isothermal compressibility at bubblepoint, Lt<sup>2</sup>/m, psi<sup>-1</sup>
 
|-
 
|-
|''M''<sub>''g''</sub>  
+
| ''K''<sub>''w''</sub>
|=  
+
| =
|gas molecular weight, m, lbm/lbm mol
+
| Watson characterization factor, °R<sup>1/3</sup>
 
|-
 
|-
|''M''<sub>''go''</sub>  
+
| ''M''<sub>''g''</sub>
|=  
+
| =
|gas/oil mixture molecular weight, m, lbm/lbm mol  
+
| gas molecular weight, m, lbm/lbm mol
 
|-
 
|-
|''M''<sub>''o''</sub>  
+
| ''M''<sub>''go''</sub>
|=  
+
| =
|oil molecular weight, m, lbm/lbm mol  
+
| gas/oil mixture molecular weight, m, lbm/lbm mol
 
|-
 
|-
|''M''<sub>''og''</sub>  
+
| ''M''<sub>''o''</sub>
|=  
+
| =
|oil-gas mixture molecular weight, m, lbm/lbm mol  
+
| oil molecular weight, m, lbm/lbm mol
 
|-
 
|-
|''p''  
+
| ''M''<sub>''og''</sub>
|=  
+
| =
|pressure, m/Lt<sup>2</sup>, psia
+
| oil-gas mixture molecular weight, m, lbm/lbm mol
 
|-
 
|-
|''p''<sub>''b''</sub>
+
| ''p''
|=  
+
| =
|bubblepoint pressure, m/Lt<sup>2</sup>, psia  
+
| pressure, m/Lt<sup>2</sup>, psia
 
|-
 
|-
|[[File:Vol1 page 0304 inline 003.png]]
+
| ''p''<sub>''b''</sub>
|=  
+
| =
|bubblepoint pressure of oil with N<sub>2</sub> present in surface gas, m/Lt<sup>2</sup>, psia  
+
| bubblepoint pressure, m/Lt<sup>2</sup>, psia
 
|-
 
|-
|''p''<sub>''bh''</sub>
+
| [[File:Vol1 page 0304 inline 003.png|RTENOTITLE]]
|=  
+
| =
|bubblepoint pressure of oil without nonhydrocarbons, m/Lt<sup>2</sup>, psia  
+
| bubblepoint pressure of oil with N<sub>2</sub> present in surface gas, m/Lt<sup>2</sup>, psia
 
|-
 
|-
|''p''<sub>''f''</sub>  
+
| ''p''<sub>''bh''</sub>
|=  
+
| =
|bubblepoint pressure factor, psia/°R
+
| bubblepoint pressure of oil without nonhydrocarbons, m/Lt<sup>2</sup>, psia
 
|-
 
|-
|''p''<sub>''r''</sub>  
+
| ''p''<sub>''f''</sub>
|=  
+
| =
|pressure ratio (fraction of bubblepoint pressure)
+
| bubblepoint pressure factor, psia/°R
 
|-
 
|-
|''R''<sub>''s''</sub>  
+
| ''p''<sub>''r''</sub>
|=  
+
| =
|solution GOR, scf/STB
+
| pressure ratio (fraction of bubblepoint pressure)
 
|-
 
|-
|''T''  
+
| ''R''<sub>''s''</sub>
|=  
+
| =
|temperature, T, °F
+
| solution GOR, scf/STB
 
|-
 
|-
|''T''<sub>''abs''</sub>
+
| ''T''
|=  
+
| =
|temperature, T, °R
+
| temperature, T, °F
 
|-
 
|-
|''T''<sub>''b''</sub>  
+
| ''T''<sub>''abs''</sub>
|=  
+
| =
|mean average boiling point temperature, T, °R  
+
| temperature, T, °R
 
|-
 
|-
|''T''<sub>''cg''</sub>  
+
| ''T''<sub>''b''</sub>
|=  
+
| =
|gas pseudocritical temperature, T, °R  
+
| mean average boiling point temperature, T, °R
 
|-
 
|-
|''T''<sub>''cm''</sub>  
+
| ''T''<sub>''cg''</sub>
|=  
+
| =
|mixture pseudocritical temperature, T, °R  
+
| gas pseudocritical temperature, T, °R
 
|-
 
|-
|''T''<sub>''co''</sub>  
+
| ''T''<sub>''cm''</sub>
|=  
+
| =
|oil pseudocritical temperature, T, °R  
+
| mixture pseudocritical temperature, T, °R
 
|-
 
|-
|''T''<sub>''r''</sub>  
+
| ''T''<sub>''co''</sub>
|=  
+
| =
|reduced temperature, T  
+
| oil pseudocritical temperature, T, °R
 
|-
 
|-
|''T''<sub>''sc''</sub>  
+
| ''T''<sub>''r''</sub>
|=  
+
| =
|temperature at standard conditions, T, °F
+
| reduced temperature, T
 
|-
 
|-
|''V''  
+
| ''T''<sub>''sc''</sub>
|=  
+
| =
|volume, L<sup>3</sup>
+
| temperature at standard conditions, T, °F
 
|-
 
|-
|''V''<sub>''o''</sub>
+
| ''V''
|=  
+
| =
|volume of crude oil, L<sup>3</sup>  
+
| volume, L<sup>3</sup>
 
|-
 
|-
|''W''<sub>''g''</sub>  
+
| ''V''<sub>''o''</sub>
|=  
+
| =
|weight of dissolved gas, m
+
| volume of crude oil, L<sup>3</sup>
 
|-
 
|-
|''W''<sub>''o''</sub>  
+
| ''W''<sub>''g''</sub>
|=  
+
| =
|weight of crude oil, m  
+
| weight of dissolved gas, m
 
|-
 
|-
|''x''<sub>''g''</sub>  
+
| ''W''<sub>''o''</sub>
|=  
+
| =
|gas "component" mole fraction in oil  
+
| weight of crude oil, m
 
|-
 
|-
|''x''<sub>''o''</sub>  
+
| ''x''<sub>''g''</sub>
|=  
+
| =
|oil "component" mole fraction in oil  
+
| gas "component" mole fraction in oil
 
|-
 
|-
|''y''<sub>''g''</sub>  
+
| ''x''<sub>''o''</sub>
|=  
+
| =
|gas "component" mole fraction in gas
+
| oil "component" mole fraction in oil
 
|-
 
|-
|[[File:Vol1 page 0305 inline 005.png]]
+
| ''y''<sub>''g''</sub>
|=  
+
| =
|mole fraction N<sub>2</sub> in surface gas  
+
| gas "component" mole fraction in gas
 
|-
 
|-
|''yo''
+
| [[File:Vol1 page 0305 inline 005.png|RTENOTITLE]]
|=  
+
| =
|oil "component" mole fraction in gas  
+
| mole fraction N<sub>2</sub> in surface gas
 
|-
 
|-
|''Z''  
+
| ''yo''
|=  
+
| =
|gas compressibility factor
+
| oil "component" mole fraction in gas
 
|-
 
|-
|''γ''<sub>API</sub>
+
| ''Z''
|=  
+
| =
|oil API gravity
+
| gas compressibility factor
 
|-
 
|-
|''γ''<sub>''g''</sub>  
+
| ''γ''<sub>API</sub>
|=  
+
| =
|gas specific gravity, air=1
+
| oil API gravity
 
|-
 
|-
|''γ''<sub>''gc''</sub>  
+
| ''γ''<sub>''g''</sub>
|=  
+
| =
|gas specific gravity adjusted for separator conditions, air=1  
+
| gas specific gravity, air=1
 
|-
 
|-
|''γ''<sub>''ghc''</sub>  
+
| ''γ''<sub>''gc''</sub>
|=  
+
| =
|gas specific gravity of hydrocarbon components in a gas mixture, air=1  
+
| gas specific gravity adjusted for separator conditions, air=1
 
|-
 
|-
|''γ''<sub>''gs''</sub>  
+
| ''γ''<sub>''ghc''</sub>
|=  
+
| =
|separator gas specific gravity, air=1  
+
| gas specific gravity of hydrocarbon components in a gas mixture, air=1
 
|-
 
|-
|''γ''<sub>''o''</sub>  
+
| ''γ''<sub>''gs''</sub>
|=  
+
| =
|oil specific gravity  
+
| separator gas specific gravity, air=1
 
|-
 
|-
|''μ''<sub>''o''</sub>  
+
| ''γ''<sub>''o''</sub>
|=  
+
| =
|oil viscosity, m/Lt, cp
+
| oil specific gravity
 
|-
 
|-
|''μ''<sub>''ob''</sub>  
+
| ''μ''<sub>''o''</sub>
|=  
+
| =
|bubblepoint oil viscosity, m/Lt, cp  
+
| oil viscosity, m/Lt, cp
 
|-
 
|-
|''μ''<sub>''od''</sub>  
+
| ''μ''<sub>''ob''</sub>
|=  
+
| =
|dead oil viscosity, m/Lt, cp  
+
| bubblepoint oil viscosity, m/Lt, cp
 
|-
 
|-
|''ρ''<sub>''g''</sub>  
+
| ''μ''<sub>''od''</sub>
|=  
+
| =
|gas density, m/L<sup>3</sup>, lbm/ft<sup>3</sup>
+
| dead oil viscosity, m/Lt, cp
 
|-
 
|-
|''ρ''<sub>''o''</sub>  
+
| ''ρ''<sub>''g''</sub>
|=  
+
| =
|oil density, m/L<sup>3</sup>, lbm/ft<sup>3</sup>  
+
| gas density, m/L<sup>3</sup>, lbm/ft<sup>3</sup>
 
|-
 
|-
|''ρ''<sub>''ob''</sub>  
+
| ''ρ''<sub>''o''</sub>
|=  
+
| =
|bubblepoint oil density, m/L<sup>3</sup>, lbm/ft<sup>3</sup>  
+
| oil density, m/L<sup>3</sup>, lbm/ft<sup>3</sup>
 
|-
 
|-
|''ρ''<sub>''w''</sub>  
+
| ''ρ''<sub>''ob''</sub>
|=  
+
| =
|water density, m/L<sup>3</sup>, g/cm<sup>3</sup>  
+
| bubblepoint oil density, m/L<sup>3</sup>, lbm/ft<sup>3</sup>
 
|-
 
|-
|''σ''<sub>''hw''</sub>  
+
| ''ρ''<sub>''w''</sub>
|=  
+
| =
|hydrocarbon/water surface tension, m/t<sup>2</sup>, dynes/cm  
+
| water density, m/L<sup>3</sup>, g/cm<sup>3</sup>
 
|-
 
|-
|''σ''<sub>''go''</sub>  
+
| ''σ''<sub>''hw''</sub>
|=  
+
| =
|gas/oil surface tension, m/t<sup>2</sup>, dynes/cm  
+
| hydrocarbon/water surface tension, m/t<sup>2</sup>, dynes/cm
 
|-
 
|-
|''σ''<sub>''od''</sub>  
+
| ''σ''<sub>''go''</sub>
|=  
+
| =
|dead oil surface tension, m/t<sup>2</sup>, dynes/cm  
+
| gas/oil surface tension, m/t<sup>2</sup>, dynes/cm
 +
|-
 +
| ''σ''<sub>''od''</sub>
 +
| =
 +
| dead oil surface tension, m/t<sup>2</sup>, dynes/cm
 
|}
 
|}
  
==References==
+
== References ==
<references>
+
 
<ref name="r1">Lasater, J.A. 1958. Bubble Point Pressure Correlations. ''J Pet Technol'' '''10''' (5): 65–67. SPE-957-G. http://dx.doi.org/10.2118/957-G.</ref>
+
<references />
<ref name="r2">Standing, M.B. 1981. ''Volumetric and Phase Behavior of Oil Field Hydrocarbon Systems'', ninth edition. Richardson, Texas: Society of Petroleum Engineers of AIME</ref>
+
 
<ref name="r3">Standing, M.B. 1947. A Pressure-Volume-Temperature Correlation for Mixtures of California Oils and Gases. ''API Drilling and Production Practice'' (1947): 275-287. </ref>
+
== Noteworthy papers in OnePetro ==
<ref name="r4">Glasø, Ø. 1980. Generalized Pressure-Volume-Temperature Correlations. ''J Pet Technol'' '''32''' (5): 785-795. SPE-8016-PA. http://dx.doi.org/10.2118/8016-PA</ref>
 
<ref name="r5">Al-Shammasi, A.A. 2001. A Review of Bubblepoint Pressure and Oil Formation Volume Factor Correlations. ''SPE Res Eval & Eng'' '''4''' (2): 146-160. SPE-71302-PA. http://dx.doi.org/10.2118/71302-PA</ref>
 
<ref name="r6">Velarde, J., Blasingame, T.A., and  McCain Jr., W.D. 1997. Correlation of Black Oil Properties At Pressures Below Bubble Point Pressure - A New Approach. Presented at the Annual Technical Meeting of CIM, Calgary, Alberta, 8–11 June. PETSOC-97-93. http://dx.doi.org/10.2118/97-93</ref>
 
<ref name="r7">Al-Marhoun, M.A. 1992. New Correlations For Formation Volume Factors Of Oil And Gas Mixtures. ''J Can Pet Technol'' '''31''' (3): 22. PETSOC-92-03-02. http://dx.doi.org/10.2118/92-03-02</ref>
 
<ref name="r8">Frashad, F., LeBlanc, J.L., Garber, J.D. et al. 1996. Empirical PVT Correlations For Colombian Crude Oils. Presented at the SPE Latin American and Caribbean Petroleum Engineering Conference, Port of Spain, Trinidad and Tobago, 23–26 April. SPE-36105-MS. http://dx.doi.org/10.2118/36105-MS</ref>
 
<ref name="r9">Kartoatmodjo, R.S.T. 1990. ''New Correlations for Estimating Hydrocarbon Liquid Properties''. MS thesis, University of Tulsa, Tulsa, Oklahoma.</ref>
 
<ref name="r10">Kartoatmodjo, T.R.S. and Schmidt, Z. 1991. ''New Correlations for Crude Oil Physical Properties'', Society of Petroleum Engineers, unsolicited paper 23556-MS.</ref>
 
<ref name="r11">Kartoatmodjo, T. and Z., S. 1994. Large Data Bank Improves Crude Physical Property Correlations. ''Oil Gas J''. '''92''' (27): 51–55.</ref>
 
<ref name="r12">Fitzgerald, D.J. 1994. ''A Predictive Method for Estimating the Viscosity of Undefined Hydrocarbon Liquid Mixtures''. MS thesis, Pennsylvania State University, State College, Pennsylvania.</ref>
 
<ref name="r13">Daubert, T.E. and Danner, R.P. 1997. ''API Technical Data Book—Petroleum Refining'', 6th edition, Chap. 11. Washington, DC: American Petroleum Institute (API).</ref>
 
<ref name="r14">Sutton, R.P. and Farshad, F. 1990. Evaluation of Empirically Derived PVT Properties for Gulf of Mexico Crude Oils. ''SPE Res Eng'' '''5''' (1): 79-86. SPE-13172-PA. http://dx.doi.org/10.2118/13172-PA</ref>
 
<ref name="r15">Whitson, C.H. and Brulé, M.R. 2000. ''Phase Behavior'', No. 20, Chap. 3. Richardson, Texas: Henry L. Doherty Monograph Series, Society of Petroleum Engineers.</ref>
 
<ref name="r16">Bergman, D.F. 2004. Don’t Forget Viscosity. Presented at the Petroleum Technology Transfer Council 2nd Annual Reservoir Engineering Symposium, Lafayette, Louisiana, 28 July.</ref>
 
<ref name="r17">Chew, J. and Connally, C.A. Jr. 1959. A Viscosity Correlation for Gas-Saturated Crude Oils. In ''Transactions of the American Institute of Mining, Metallurgical, and Petroleum Engineers'', Vol. 216, 23. Dallas, Texas: Society of Petroleum Engineers of AIME.</ref>
 
<ref name="r18">Aziz, K. and Govier, G.W. 1972. Pressure Drop in Wells Producing Oil and Gas. ''J Can Pet Technol'' '''11''' (3): 38. PETSOC-72-03-04. http://dx.doi.org/10.2118/72-03-04</ref>
 
<ref name="r19">Beggs, H.D. and Robinson, J.R. 1975. Estimating the Viscosity of Crude Oil Systems. ''J Pet Technol'' '''27''' (9): 1140-1141. SPE-5434-PA. http://dx.doi.org/10.2118/5434-PA</ref>
 
<ref name="r20">Vazquez, M.E. 1976. ''Correlations for Fluid Physical Property Prediction''. MS thesis, University of Tulsa, Tulsa, Oklahoma.</ref>
 
<ref name="r21">Vazquez, M. and Beggs, H.D. 1980. Correlations for Fluid Physical Property Prediction. ''J Pet Technol'' '''32''' (6): 968-970. SPE-6719-PA. http://dx.doi.org/10.2118/6719-PA</ref>
 
<ref name="r22">Beal, C. 1970. ''The Viscosity of Air, Water, Natural Gas, Crude Oil and Its Associated Gases at Oil Field Temperatures and Pressures'', No. 3, 114–127. Richardson, Texas: Reprint Series (Oil and Gas Property Evaluation and Reserve Estimates), SPE.</ref>
 
<ref name="r23">Kouzel, B. 1965. How Pressure Affects Liquid Viscosity. ''Hydrocarb. Process''. (March 1965): 120.</ref>
 
<ref name="r24">Abdul-Majeed, G.H. and Abu Al-Soof, N.B. 2000. Estimation of gas–oil surface tension. ''J. Pet. Sci. Eng''. '''27''' (3–4): 197-200. http://dx.doi.org/10.1016/S0920-4105(00)00058-9</ref>
 
<ref name="r25">Baker, O. and Swerdloff, W. 1955. Calculation of Surface Tension 3—Calculating parachor Values. ''Oil Gas J''. (5 December 1955): 141.</ref>
 
<ref name="r26">Baker, O. and Swerdloff, W. 1956. Calculation of Surface Tension 6—Finding Surface Tension of Hydrocarbon Liquids. ''Oil Gas J''. (2 January 1956): 125.</ref>
 
<ref name="r27">Firoozabadi, A. and Ramey Jr., H.J. 1988. Surface Tension of Water-Hydrocarbon Systems at Reservoir Conditions. ''J Can Pet Technol'' '''27''' (May–June): 41–48.</ref>
 
</references>
 
  
==Noteworthy papers in OnePetro==
 
 
Use this section to list papers in OnePetro that a reader who wants to learn more should definitely read
 
Use this section to list papers in OnePetro that a reader who wants to learn more should definitely read
  
==External links==
+
== External links ==
 +
 
 
Use this section to provide links to relevant material on websites other than PetroWiki and OnePetro
 
Use this section to provide links to relevant material on websites other than PetroWiki and OnePetro
  
==See also==
+
== See also ==
[[Oil fluid properties]]
+
 
 +
[[Oil_fluid_properties|Oil fluid properties]]
 +
 
 +
[[PEH:Oil_System_Correlations]]
  
[[PEH:Oil System Correlations]]
+
[[Category:5.2.1 Phase behavior and PVT measurements]]

Revision as of 16:01, 4 June 2015

This is an example of calculating PVT properties. The specific correlations that should be used for a specific crude oil or reservoir may vary, as discussed in the referenced pages focusing on specific properties.

Determine the PVT properties for a United States midcontinental crude oil and natural gas system with properties listed in Table 1. Table 2 lists the correlations to be used. Measured data are provided for comparison with the calculated results. For correlations that rely on other correlations, these data illustrate the effects of error propagation in the calculations.

Gravity and molecular weight

Determine the crude oil specific gravity,

RTENOTITLE....................(1)

and molecular weight,

RTENOTITLE....................(2)

Bubblepoint pressure

Use the Lasater[1] correlation to estimate bubblepoint pressure. Calculate the gas mole fraction in the oil,

RTENOTITLE....................(3)

and the Lasater bubblepoint pressure factor,

RTENOTITLE....................(4)

with Lasater’s relationship between bubblepoint pressure factor and bubblepoint pressure,

RTENOTITLE....................(5)

For comparison, Standing[2][3] = 2,316 psia, Glasø[4] = 2,725 psia, Al-Shammasi[5] = 2,421 psia, and Velardi[6] = 2,411 psia.

Modify the calculated bubblepoint pressure to account for the effects of nitrogen in the surface gas with Jacobson’s equation.

RTENOTITLE....................(6)

Therefore, the bubblepoint pressure should be increased by 9.8% to 2,251 psia. The measured bubblepoint pressure was reported to be 2,479 psia.

Bubblepoint oil formation volume factor

Calculate the bubblepoint oil formation volume factor (FVF) using the correlation from Al-Shammasi.[5]

RTENOTITLE....................(7)

RTENOTITLE

For comparison (in bbl/STB), Standing[2][3] = 1.410, Glasø[4] = 1.386, Al-Marhoun[7] = 1.364, Farshad[8] = 1.364, and Kartoatmodjo[9][10][11] = 1.358. The measured bubblepoint oil FVF is 1.398 bbl/STB.

Isothermal compressibility

Calculate the isothermal compressibility of oil using the Farshad[8] correlation.

RTENOTITLE....................(8)

RTENOTITLE....................(9)

RTENOTITLE

The measured isothermal compressibility is 11.06 × 10-6psi-1.

Undersaturated oil formation volume factor

With the results from Lasater’s[1] method for bubblepoint pressure, use Al-Shammasi’s[5] method for bubblepoint oil FVF, and Farshad’s[8] equation for isothermal compressibility, the undersaturated oil FVF is given by

RTENOTITLE....................(10)

RTENOTITLE

which compares to a measured value of 1.367 bbl/STB. Because this calculation uses the results from multiple correlations, individual correlation error compounds and propagates through to the final result. The calculated value is 1.367 bbl/STB with the actual bubblepoint value of 1.398 bbl/STB; therefore, the accuracy of the bubblepoint FVF is primarily affected by the accuracy of the undersaturated FVF.

Oil density

Calculate the oil density.

RTENOTITLE....................(11)

Dead oil viscosity

Calculate the dead oil viscosity using the correlation from Glasø.[4]

RTENOTITLE....................(12)

For comparison, Fitzgerald[12][13][14] = 1.808 cp, and Bergman[15][16] = 2.851 cp. The measured dead oil viscosity is 1.67 cp.

Bubblepoint oil viscosity

Calculate the bubblepoint oil viscosity using the method developed by Chew and Connally.[17][18]

RTENOTITLE....................(13)

RTENOTITLE....................(14)

RTENOTITLE....................(15)

For comparison, Beggs and Robinson[19] = 0.515 cp. The measured viscosity at bubblepoint is 0.401 cp.

Undersaturated oil viscosity

Calculate the undersaturated oil viscosity by applying the Vazquez and Beggs[20][21] correlation.

RTENOTITLE....................(16)

RTENOTITLE

For comparison, Beal[22] = 0.730 cp and Kouzel[23] = 0.778 cp. The measured value is 0.475 cp. This example illustrates the steps necessary to calculate oil viscosity requiring correlations for dead oil viscosity, bubblepoint viscosity, undersaturated viscosity, and bubblepoint pressure/solution GOR. Errors in individual correlations can compound and propagate through to the resulting answer. For instance, if the measured bubblepoint viscosity is used in Eq. 16, the result is 0.52 cp—much closer to the measured value. Therefore, care should be exercised in the selection of accurate correlations for individual properties.

Gas/oil interfacial tension

Estimate the gas/oil surface tension using the method developed by Abdul-Majeed.[24] Calculate the dead oil surface tension.

RTENOTITLE....................(17)

RTENOTITLE

Determine the live oil adjustment factor.

RTENOTITLE....................(18)

RTENOTITLE

Calculate the live gas/oil surface tension.

RTENOTITLE....................(19)

RTENOTITLE

For comparison, Baker and Swerdloff[25][26] = 4.73 dynes/cm.

Water/oil interfacial tension

Estimate the water/oil surface tension using Firoozabadi and Ramey.[27] Calculate the pseudocritical temperature of the dead oil.

RTENOTITLE....................(20)

RTENOTITLE

Calculate the pseudocritical temperature of the gas.

RTENOTITLE....................(21)

RTENOTITLE

Calculate the pseudocritical temperature of the live gas/oil mixture.

RTENOTITLE....................(22)

Convert oil density units from lbm/ft3 to g/cm3.

RTENOTITLE....................(23)

Calculate the surface tension between the oil and water phases.

RTENOTITLE....................(24)

RTENOTITLE

Nomenclature

Bg = gas FVF, ft3/scf
Bo = oil FVF, bbl/STB
Bob = oil formation volume at bubblepoint pressure, bbl/STB
co = oil isothermal compressibility, Lt2/m, psi-1
cob = oil isothermal compressibility at bubblepoint, Lt2/m, psi-1
Kw = Watson characterization factor, °R1/3
Mg = gas molecular weight, m, lbm/lbm mol
Mgo = gas/oil mixture molecular weight, m, lbm/lbm mol
Mo = oil molecular weight, m, lbm/lbm mol
Mog = oil-gas mixture molecular weight, m, lbm/lbm mol
p = pressure, m/Lt2, psia
pb = bubblepoint pressure, m/Lt2, psia
RTENOTITLE = bubblepoint pressure of oil with N2 present in surface gas, m/Lt2, psia
pbh = bubblepoint pressure of oil without nonhydrocarbons, m/Lt2, psia
pf = bubblepoint pressure factor, psia/°R
pr = pressure ratio (fraction of bubblepoint pressure)
Rs = solution GOR, scf/STB
T = temperature, T, °F
Tabs = temperature, T, °R
Tb = mean average boiling point temperature, T, °R
Tcg = gas pseudocritical temperature, T, °R
Tcm = mixture pseudocritical temperature, T, °R
Tco = oil pseudocritical temperature, T, °R
Tr = reduced temperature, T
Tsc = temperature at standard conditions, T, °F
V = volume, L3
Vo = volume of crude oil, L3
Wg = weight of dissolved gas, m
Wo = weight of crude oil, m
xg = gas "component" mole fraction in oil
xo = oil "component" mole fraction in oil
yg = gas "component" mole fraction in gas
RTENOTITLE = mole fraction N2 in surface gas
yo = oil "component" mole fraction in gas
Z = gas compressibility factor
γAPI = oil API gravity
γg = gas specific gravity, air=1
γgc = gas specific gravity adjusted for separator conditions, air=1
γghc = gas specific gravity of hydrocarbon components in a gas mixture, air=1
γgs = separator gas specific gravity, air=1
γo = oil specific gravity
μo = oil viscosity, m/Lt, cp
μob = bubblepoint oil viscosity, m/Lt, cp
μod = dead oil viscosity, m/Lt, cp
ρg = gas density, m/L3, lbm/ft3
ρo = oil density, m/L3, lbm/ft3
ρob = bubblepoint oil density, m/L3, lbm/ft3
ρw = water density, m/L3, g/cm3
σhw = hydrocarbon/water surface tension, m/t2, dynes/cm
σgo = gas/oil surface tension, m/t2, dynes/cm
σod = dead oil surface tension, m/t2, dynes/cm

References

  1. 1.0 1.1 Lasater, J.A. 1958. Bubble Point Pressure Correlations. J Pet Technol 10 (5): 65–67. SPE-957-G. http://dx.doi.org/10.2118/957-G.
  2. 2.0 2.1 Standing, M.B. 1981. Volumetric and Phase Behavior of Oil Field Hydrocarbon Systems, ninth edition. Richardson, Texas: Society of Petroleum Engineers of AIME
  3. 3.0 3.1 Standing, M.B. 1947. A Pressure-Volume-Temperature Correlation for Mixtures of California Oils and Gases. API Drilling and Production Practice (1947): 275-287.
  4. 4.0 4.1 4.2 Glasø, Ø. 1980. Generalized Pressure-Volume-Temperature Correlations. J Pet Technol 32 (5): 785-795. SPE-8016-PA. http://dx.doi.org/10.2118/8016-PA
  5. 5.0 5.1 5.2 Al-Shammasi, A.A. 2001. A Review of Bubblepoint Pressure and Oil Formation Volume Factor Correlations. SPE Res Eval & Eng 4 (2): 146-160. SPE-71302-PA. http://dx.doi.org/10.2118/71302-PA
  6. Velarde, J., Blasingame, T.A., and McCain Jr., W.D. 1997. Correlation of Black Oil Properties At Pressures Below Bubble Point Pressure - A New Approach. Presented at the Annual Technical Meeting of CIM, Calgary, Alberta, 8–11 June. PETSOC-97-93. http://dx.doi.org/10.2118/97-93
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External links

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See also

Oil fluid properties

PEH:Oil_System_Correlations