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Calculating PVT properties: Difference between revisions
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This is an example of calculating PVT 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 == | ||
[[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 == | ||
[[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 [[ | |||
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 | [[File:Vol1 page 0294 eq 003.png|RTENOTITLE]] | ||
The measured isothermal compressibility is 11.06 × 10<sup>-6</sup>psi<sup>-1</sup>. | |||
== Undersaturated oil formation volume factor == | |||
== | 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 | ||
[[File:Vol1 page 0294 eq | [[File:Vol1 page 0294 eq 004.png|RTENOTITLE]]....................(10) | ||
[[File:Vol1 page 0294 eq | [[File:Vol1 page 0294 eq 005.png|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|oil density]]. | |||
[[File:Vol1 page | [[File:Vol1 page 0295 eq 001.png|RTENOTITLE]]....................(11) | ||
== Dead oil viscosity == | |||
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> | |||
[[File:Vol1 page 0295 eq 002.png|RTENOTITLE]]....................(12) | |||
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. | |||
== | == Bubblepoint oil viscosity == | ||
[[ | 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> | ||
[[File:Vol1 page 0295 eq 003.png|RTENOTITLE]]....................(13) | |||
[[File:Vol1 page 0296 eq 001.png|RTENOTITLE]]....................(14) | |||
[[File:Vol1 page | [[File:Vol1 page 0296 eq 002.png|RTENOTITLE]]....................(15) | ||
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. | |||
== Undersaturated oil viscosity == | |||
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. | |||
[[File:Vol1 page 0296 eq 003.png|RTENOTITLE]]....................(16) | |||
[[File:Vol1 page 0296 eq | [[File:Vol1 page 0296 eq 004.png|RTENOTITLE]] | ||
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. | |||
== 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 [[ | |||
[[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">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 == | |||
{| | {| | ||
|- | |- | ||
|''B''<sub>'' | | ''B''<sub>''g''</sub> | ||
|= | | = | ||
| | | gas FVF, ft<sup>3</sup>/scf | ||
|- | |- | ||
|''B''<sub>'' | | ''B''<sub>''o''</sub> | ||
|= | | = | ||
|oil | | oil FVF, bbl/STB | ||
|- | |- | ||
|'' | | ''B''<sub>''ob''</sub> | ||
|= | | = | ||
|oil | | oil formation volume at bubblepoint pressure, bbl/STB | ||
|- | |- | ||
|''c''<sub>'' | | ''c''<sub>''o''</sub> | ||
|= | | = | ||
|oil isothermal compressibility | | oil isothermal compressibility, Lt<sup>2</sup>/m, psi<sup>-1</sup> | ||
|- | |- | ||
|'' | | ''c''<sub>''ob''</sub> | ||
|= | | = | ||
| | | oil isothermal compressibility at bubblepoint, Lt<sup>2</sup>/m, psi<sup>-1</sup> | ||
|- | |- | ||
|'' | | ''K''<sub>''w''</sub> | ||
|= | | = | ||
| | | Watson characterization factor, °R<sup>1/3</sup> | ||
|- | |- | ||
|''M''<sub>'' | | ''M''<sub>''g''</sub> | ||
|= | | = | ||
|gas | | gas molecular weight, m, lbm/lbm mol | ||
|- | |- | ||
|''M''<sub>'' | | ''M''<sub>''go''</sub> | ||
|= | | = | ||
|oil molecular weight, m, lbm/lbm mol | | gas/oil mixture molecular weight, m, lbm/lbm mol | ||
|- | |- | ||
|''M''<sub>'' | | ''M''<sub>''o''</sub> | ||
|= | | = | ||
|oil | | oil molecular weight, m, lbm/lbm mol | ||
|- | |- | ||
|'' | | ''M''<sub>''og''</sub> | ||
|= | | = | ||
| | | oil-gas mixture molecular weight, m, lbm/lbm mol | ||
|- | |- | ||
|''p'' | | ''p'' | ||
|= | | = | ||
| | | pressure, m/Lt<sup>2</sup>, psia | ||
|- | |- | ||
| | | ''p''<sub>''b''</sub> | ||
|= | | = | ||
|bubblepoint pressure | | bubblepoint pressure, m/Lt<sup>2</sup>, psia | ||
|- | |- | ||
| | | [[File:Vol1 page 0304 inline 003.png|RTENOTITLE]] | ||
|= | | = | ||
|bubblepoint pressure of oil | | bubblepoint pressure of oil with N<sub>2</sub> present in surface gas, m/Lt<sup>2</sup>, psia | ||
|- | |- | ||
|''p''<sub>'' | | ''p''<sub>''bh''</sub> | ||
|= | | = | ||
|bubblepoint pressure | | bubblepoint pressure of oil without nonhydrocarbons, m/Lt<sup>2</sup>, psia | ||
|- | |- | ||
|''p''<sub>'' | | ''p''<sub>''f''</sub> | ||
|= | | = | ||
| | | bubblepoint pressure factor, psia/°R | ||
|- | |- | ||
|'' | | ''p''<sub>''r''</sub> | ||
|= | | = | ||
| | | pressure ratio (fraction of bubblepoint pressure) | ||
|- | |- | ||
|'' | | ''R''<sub>''s''</sub> | ||
|= | | = | ||
| | | solution GOR, scf/STB | ||
|- | |- | ||
|''T'' | | ''T'' | ||
|= | | = | ||
|temperature, T, | | temperature, T, °F | ||
|- | |- | ||
|''T''<sub>'' | | ''T''<sub>''abs''</sub> | ||
|= | | = | ||
| | | temperature, T, °R | ||
|- | |- | ||
|''T''<sub>'' | | ''T''<sub>''b''</sub> | ||
|= | | = | ||
| | | mean average boiling point temperature, T, °R | ||
|- | |- | ||
|''T''<sub>'' | | ''T''<sub>''cg''</sub> | ||
|= | | = | ||
| | | gas pseudocritical temperature, T, °R | ||
|- | |- | ||
|''T''<sub>'' | | ''T''<sub>''cm''</sub> | ||
|= | | = | ||
| | | mixture pseudocritical temperature, T, °R | ||
|- | |- | ||
|''T''<sub>'' | | ''T''<sub>''co''</sub> | ||
|= | | = | ||
| | | oil pseudocritical temperature, T, °R | ||
|- | |- | ||
|''T''<sub>'' | | ''T''<sub>''r''</sub> | ||
|= | | = | ||
|temperature | | reduced temperature, T | ||
|- | |- | ||
|'' | | ''T''<sub>''sc''</sub> | ||
|= | | = | ||
| | | temperature at standard conditions, T, °F | ||
|- | |- | ||
|''V'' | | ''V'' | ||
|= | | = | ||
|volume | | volume, L<sup>3</sup> | ||
|- | |- | ||
|'' | | ''V''<sub>''o''</sub> | ||
|= | | = | ||
| | | volume of crude oil, L<sup>3</sup> | ||
|- | |- | ||
|''W''<sub>'' | | ''W''<sub>''g''</sub> | ||
|= | | = | ||
|weight of | | weight of dissolved gas, m | ||
|- | |- | ||
|'' | | ''W''<sub>''o''</sub> | ||
|= | | = | ||
| | | weight of crude oil, m | ||
|- | |- | ||
|''x''<sub>'' | | ''x''<sub>''g''</sub> | ||
|= | | = | ||
| | | gas "component" mole fraction in oil | ||
|- | |- | ||
|'' | | ''x''<sub>''o''</sub> | ||
|= | | = | ||
| | | oil "component" mole fraction in oil | ||
|- | |- | ||
| | | ''y''<sub>''g''</sub> | ||
|= | | = | ||
|mole fraction | | gas "component" mole fraction in gas | ||
|- | |- | ||
| | | [[File:Vol1 page 0305 inline 005.png|RTENOTITLE]] | ||
|= | | = | ||
| | | mole fraction N<sub>2</sub> in surface gas | ||
|- | |- | ||
|'' | | ''yo'' | ||
|= | | = | ||
|gas | | oil "component" mole fraction in gas | ||
|- | |- | ||
|'' | | ''Z'' | ||
|= | | = | ||
| | | gas compressibility factor | ||
|- | |- | ||
|''γ''<sub> | | ''γ''<sub>API</sub> | ||
|= | | = | ||
| | | oil API gravity | ||
|- | |- | ||
|''γ''<sub>'' | | ''γ''<sub>''g''</sub> | ||
|= | | = | ||
|gas specific gravity | | gas specific gravity, air=1 | ||
|- | |- | ||
|''γ''<sub>'' | | ''γ''<sub>''gc''</sub> | ||
|= | | = | ||
|gas specific gravity | | gas specific gravity adjusted for separator conditions, air=1 | ||
|- | |- | ||
|''γ''<sub>'' | | ''γ''<sub>''ghc''</sub> | ||
|= | | = | ||
| | | gas specific gravity of hydrocarbon components in a gas mixture, air=1 | ||
|- | |- | ||
|''γ''<sub>'' | | ''γ''<sub>''gs''</sub> | ||
|= | | = | ||
| | | separator gas specific gravity, air=1 | ||
|- | |- | ||
|'' | | ''γ''<sub>''o''</sub> | ||
|= | | = | ||
|oil | | oil specific gravity | ||
|- | |- | ||
|''μ''<sub>'' | | ''μ''<sub>''o''</sub> | ||
|= | | = | ||
| | | oil viscosity, m/Lt, cp | ||
|- | |- | ||
|''μ''<sub>'' | | ''μ''<sub>''ob''</sub> | ||
|= | | = | ||
| | | bubblepoint oil viscosity, m/Lt, cp | ||
|- | |- | ||
|'' | | ''μ''<sub>''od''</sub> | ||
|= | | = | ||
| | | dead oil viscosity, m/Lt, cp | ||
|- | |- | ||
|''ρ''<sub>'' | | ''ρ''<sub>''g''</sub> | ||
|= | | = | ||
| | | gas density, m/L<sup>3</sup>, lbm/ft<sup>3</sup> | ||
|- | |- | ||
|''ρ''<sub>'' | | ''ρ''<sub>''o''</sub> | ||
|= | | = | ||
| | | oil density, m/L<sup>3</sup>, lbm/ft<sup>3</sup> | ||
|- | |- | ||
|''ρ''<sub>'' | | ''ρ''<sub>''ob''</sub> | ||
|= | | = | ||
| | | bubblepoint oil density, m/L<sup>3</sup>, lbm/ft<sup>3</sup> | ||
|- | |- | ||
|'' | | ''ρ''<sub>''w''</sub> | ||
|= | | = | ||
| | | water density, m/L<sup>3</sup>, g/cm<sup>3</sup> | ||
|- | |- | ||
|''σ''<sub>'' | | ''σ''<sub>''hw''</sub> | ||
|= | | = | ||
| | | 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 | |||
<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]] | |||
[[ | [[Category:5.2.1 Phase behavior and PVT measurements]] |
Revision as of 17:01, 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,
and molecular weight,
Bubblepoint pressure
Use the Lasater[1] correlation to estimate bubblepoint pressure. Calculate the gas mole fraction in the oil,
and the Lasater bubblepoint pressure factor,
with Lasater’s relationship between bubblepoint pressure factor and bubblepoint pressure,
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.
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]
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.
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
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.
Dead oil viscosity
Calculate the dead oil viscosity using the correlation from Glasø.[4]
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]
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.
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.
Determine the live oil adjustment factor.
Calculate the live gas/oil surface tension.
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.
Calculate the pseudocritical temperature of the gas.
Calculate the pseudocritical temperature of the live gas/oil mixture.
Convert oil density units from lbm/ft3 to g/cm3.
Calculate the surface tension between the oil and water phases.
Nomenclature
References
- ↑ 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.
- ↑ 2.0 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
- ↑ 3.0 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.
- ↑ 4.0 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
- ↑ 5.0 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
- ↑ 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
- ↑ 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
- ↑ 8.0 8.1 8.2 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
- ↑ Kartoatmodjo, R.S.T. 1990. New Correlations for Estimating Hydrocarbon Liquid Properties. MS thesis, University of Tulsa, Tulsa, Oklahoma.
- ↑ Kartoatmodjo, T.R.S. and Schmidt, Z. 1991. New Correlations for Crude Oil Physical Properties, Society of Petroleum Engineers, unsolicited paper 23556-MS.
- ↑ Kartoatmodjo, T. and Z., S. 1994. Large Data Bank Improves Crude Physical Property Correlations. Oil Gas J. 92 (27): 51–55.
- ↑ Fitzgerald, D.J. 1994. A Predictive Method for Estimating the Viscosity of Undefined Hydrocarbon Liquid Mixtures. MS thesis, Pennsylvania State University, State College, Pennsylvania.
- ↑ Daubert, T.E. and Danner, R.P. 1997. API Technical Data Book—Petroleum Refining, 6th edition, Chap. 11. Washington, DC: American Petroleum Institute (API).
- ↑ 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
- ↑ 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.
- ↑ Bergman, D.F. 2004. Don’t Forget Viscosity. Presented at the Petroleum Technology Transfer Council 2nd Annual Reservoir Engineering Symposium, Lafayette, Louisiana, 28 July.
- ↑ 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.
- ↑ 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
- ↑ 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
- ↑ Vazquez, M.E. 1976. Correlations for Fluid Physical Property Prediction. MS thesis, University of Tulsa, Tulsa, Oklahoma.
- ↑ 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
- ↑ 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.
- ↑ Kouzel, B. 1965. How Pressure Affects Liquid Viscosity. Hydrocarb. Process. (March 1965): 120.
- ↑ 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
- ↑ Baker, O. and Swerdloff, W. 1955. Calculation of Surface Tension 3—Calculating parachor Values. Oil Gas J. (5 December 1955): 141.
- ↑ Baker, O. and Swerdloff, W. 1956. Calculation of Surface Tension 6—Finding Surface Tension of Hydrocarbon Liquids. Oil Gas J. (2 January 1956): 125.
- ↑ 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.
Noteworthy papers in OnePetro
Use this section to list papers in OnePetro that a reader who wants to learn more should definitely read
External links
Use this section to provide links to relevant material on websites other than PetroWiki and OnePetro