The Impact of Vapor/Liquid-Equilibria Calculations on Scale-Prediction Modeling
- Ayrton S. Ribeiro (Heriot-Watt University) | Duarte Silva (Heriot-Watt University) | Eric J. Mackay (Heriot-Watt University) | Ken Sorbie (Heriot-Watt University)
- Document ID
- Society of Petroleum Engineers
- SPE Production & Operations
- Publication Date
- February 2017
- Document Type
- Journal Paper
- 64 - 72
- 2017.Society of Petroleum Engineers
- CaCO3, Equation of State, FeS, CO2 and H2S
- 1 in the last 30 days
- 240 since 2007
- Show more detail
- View rights & permissions
|SPE Member Price:||USD 10.00|
|SPE Non-Member Price:||USD 30.00|
Vapor/liquid-equilibria (VLE) calculations, particularly involving the phase behavior of carbon dioxide (CO2) and hydrogen sulfide (H2S), are used in scale-prediction modeling. In this work, the impact of VLE calculations for CO2- and H2S-rich gas phases and for acid- and sour-gas mixtures on scale-prediction calculations is evaluated.
Three equations of state (EOSs)--Soave-Redlich-Kwong (SRK) (Soave 1972), Peng-Robinson (PR) (Peng and Robinson 1976), and Valderrama-Patel-Teja (VPT) (Valderrama 1990)--are implemented in the Heriot-Watt model and used in VLE calculations. The solubility of single-component CO2 and H2S in water and the solubility of a gas mixture in water were compared with experimental data in terms of the absolute relative deviation (ARD). The solubility data were then used in PHREEQC (USGS 2016) to calculate the impact of using different EOSs on carbonate and sulfide scales, particularly on calcium carbonate (CaCO3) and iron sulfide (FeS).
Average ARDs of 6.04, 4.10, and 3.77% between experimental and calculated values for CO2 solubility in water were obtained for the SRK, PR, and VPT EOSs, respectively. Similarly, for H2S solubility in water, average ARDs of 6.49, 6.66, and 6.48% were obtained for each EOS, respectively. For the solubility of sour- and acid-gas mixtures in water, average ARDs of 13.92, 13.25, and 10.78% were obtained, respectively. It has thus been concluded that the VPT EOS performs better than the SRK and PR EOSs in VLE calculations for the analyzed data.
The errors introduced in VLE calculations have been found to impact the calculation of the amount of CaCO3 precipitated, with consequences for scale-inhibitor selection. Higher deviations were found in the amount of CaCO3 precipitation for gas mixtures when compared with a single-component, CO2-rich phase. Furthermore, the large errors occurring in VLE calculations for H2S solubility have not been found to impact the calculation of the amount of FeS precipitated when H2S is in excess with respect to Fe2+. In addition to this, a case study that was performed by use of formation-water data from the Brazilian presalt revealed that the choice of EOS can cause errors of 6 kg of precipitate during each day of production.
Scale-prediction calculations carried out with PHREEQC demonstrate that VLE calculations can have a high impact on mineral precipitation. Thus, it is recommended that the best VLE model available should always be used for scale-prediction modeling, particularly when mixtures of gases are present.
|File Size||1 MB||Number of Pages||9|
Appelo, C. A. J. 2015. Principles, Caveats and Improvements in Databases for Calculating Hydrogeochemical Reactions in Saline Waters From 0 to 200°C and 1 to 1000 atm. Applied Geochemistry 55: 62–71. http://dx.doi.org/10.1016/j.apgeochem.2014.11.007.
Benning, L. G., Wilkin, R. T., and Barnes, H. L. 2000. Reaction Pathways in the Fe–S System Below 100°C. Chemical Geology 167 (1–2): 25–51. http://dx.doi.org/10.1016/S0009-2541(99)00198-9.
Bezerra, M. C. M., Rosario, F. F., and Rosa, K. R. S. A. 2013. Scale Management in Deep and Ultradeep Water Fields. Presented at the Offshore Technology Conference-Brasil, Rio de Janeiro, 29–31 October. OTC-24508-MS. http://dx.doi.org/10.4043/24508-MS.
Boyd, A., Souza, A., Carneiro, G. et al. 2015. Presalt Carbonate Evaluation for Santos Basin, Offshore Brazil. Petrophysics 56 (6): 577–591. SPWLA-2015-v56n6a2.
Chapoy, A., Mohammadi, A. H., Richon, D. et al. 2004. Gas Solubility Measurement and Modeling for Methane–Water and Methane–Ethane–n-Butane–Water Systems at Low Temperature Conditions. Fluid Phase Equilibria 220 (1): 111–119. http://dx.doi.org/10.1016/j.fluid.2004.02.010.
Chapoy, A., Mohammadi, A. H., Tohidi, B. et al. 2005. Experimental Measurement and Phase Behavior Modeling of Hydrogen Sulfide—Water Binary System. Ind. Eng. Chem. Res. 44 (19): 7567–7574. http://dx.doi.org/10.1021/ie050201h.
Cruz, R., Rosa, M. B., Branco, C. et al. 2016. Lula NE Pilot Project – An Ultra-Deep Success in the Brazilian Pre-Salt. Presented at the Offshore Technology Conference, Houston, 2–5 May. OTC-27297-MS. http://dx.doi.org/10.4043/27297-MS.
Harvey, A. H. 1996. Semiempirical Correlation for Henry’s Constants Over Large Temperature Ranges. AIChE Journal 42 (5): 1491–1494. http://dx.doi.org/10.1002/aic.690420531.
Harvie, C. E., Møller, N., and Weare, J. H. 1984. The Prediction of Mineral Solubilities in Natural Waters: The Na-K-Mg-Ca-H-Cl-SO4-OHHCO3-CO3-CO2-H2O System to High Ionic Strengths at 25°C. Geochimica et Cosmochimica Acta 48 (4): 723–751. http://dx.doi.org/10.1016/0016-7037(84)90098-X.
Leal Jauregui, J. A., Solares, J. R., Nasr-El-Din, H. A. et al. 2007. A Systematic Approach To Remove Iron Sulphide Scale: A Case History. Presented at the SPE Middle East Oil and Gas Show and Conference, Manama, Bahrain, 11–14 March. SPE-105607-MS. http://dx.doi.org/10.2118/105607-MS.
Li, Y. and Nghiem, L. X. 1986. Phase Equilibria of Oil, Gas and Water/Brine Mixtures From a Cubic Equation of State and Henry’s Law. The Canadian Journal of Chemical Engineering 64 (3): 486–496. http://dx.doi.org/10.1002/cjce.5450640319.
Muller, E. A. and Olivera-Fuentes, C. 1989. General Expressions for Multicomponent Fugacity Coefficients and Residual Properties from Cubic Equations of State. Latin American Applied Research 19: 99–109.
Parkhurst, D. L. and Appelo, C. A. J. 2013. Description of Input and Examples for PHREEQC Version 3—A Computer Program for Speciation, Batch-Reaction, One-Dimensional Transport, and Inverse Geochemical Calculations: U. S. Geological Survey Techniques and Methods, Book 6, Chapter A43, 132–138. Denver: USGS, http://pubs.usgs.gov/tm/06/a43/.
Peng, D.-Y. and Robinson, D. B. 1976. A New Two-Constant Equation of State. Ind. Eng. Chem. Fundamen. 15 (1): 59–64. http://dx.doi.org/10.1021/i160057a011.
Plummer, L. N., Wigley, T. M. L., and Parkhurst, D. L. 1978. The Kinetics of Calcite Dissolution in CO2-Water Systems at 5° to 60°C and 0.0 to 1.0 atm CO2. American Journal of Science 278 (2): 179–216. http://dx.doi.org/10.2475/ajs.278.2.179.
Poling, B. E., Prausnitz, J. M., and O’Connell, J. P. 2001. The Properties of Gases and Liquids, fifth edition, McGraw-Hill.
Prausnitz, J. M., Lichtenthaler, R. N., and Azevedo, E. G. D. 1999. Molecular Thermodynamics of Fluid-Phase Equilibria. Upper Saddle River, New Jersey: Prentice Hall PTR.
Soave, G. 1972. Equilibrium Constants From a Modified Redlich-Kwong Equation of State. Chemical Engineering Science 27 (6): 1197–1203. http://dx.doi.org/10.1016/0009-2509(72)80096-4.
Spycher, N., Pruess, K., and Ennis-King, J. 2003. CO2-H2O Mixtures in the Geological Sequestration of CO2. I. Assessment and Calculation of Mutual Solubilities From 12 to 100°C and up to 600 bar. Geochimica et Cosmochimica Acta 67 (16): 3015–3031. http://dx.doi.org/10.1016/S0016-7037(03)00273-4.
U.S. Geological Survey (USGS). 2016. PHREEQC (Version 3)--A Computer Program for Speciation, Batch-Reaction, One-Dimensional Transport, and Inverse Geochemical Calculations. http://wwwbrr.cr.usgs.gov/projects/GWC_coupled/phreeqc/index.html (last modified 13 September 2016).
Valderrama, J. O. 1990. A Generalized Patel-Teja Equation of State for Polar and Nonpolar Fluids and Their Mixtures. Journal of Chemical Engineering of Japan 23 (1): 87–91. http://dx.doi.org/10.1252/jcej.23.87.
Wagner, W. and Pruss, A. 1993. International Equations for the Saturation Properties of Ordinary Water Substance. Revised According to the International Temperature Scale of 1990. Addendum to J. Phys. Chem. Ref. Data 16, 893 (1987). J. Phys. Chem. Ref. Data 22: 783–787. http://dx.doi.org/10.1063/1.555926.
Zirrahi, M., Azin, R., Hassanzadeh, H. et al. 2012. Mutual Solubility of CH4, CO2, H2S, and Their Mixtures in Brine Under Subsurface Disposal Conditions. Fluid Phase Equilibria 324: 80–93. http://dx.doi.org/10.1016/j.fluid.2012.03.017.