Cubic Equations of State Applied to HT/HP and Highly Aromatic Fluids

Pedersen, Karen Schou; Milter, J.; Sörensen, Henrik

doi:10.2118/88364-pa

Cited by 73 publications

(25 citation statements)

References 11 publications

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“…The volumetric properties of bitumen and gas-saturated bitumen can also be calculated by equation of state. Péneloux et al (1982) proposed a volume-translation technique to improve the volumetric results for the modified Peng-Robinson equation of state (Robinson and Peng 1978). On the basis of the Péneloux et al (1982) technique, a certain translation along the volume axis can be applied while the other equilibrium properties remain unchanged.…”

Section: Prediction Of Liquid Densitiesmentioning

confidence: 99%

“…Péneloux et al (1982) proposed a volume-translation technique to improve the volumetric results for the modified Peng-Robinson equation of state (Robinson and Peng 1978). On the basis of the Péneloux et al (1982) technique, a certain translation along the volume axis can be applied while the other equilibrium properties remain unchanged. Therefore, the density predictions were improved, while the other properties would not be affected.…”

Section: Prediction Of Liquid Densitiesmentioning

confidence: 99%

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Measurement and Correlation of Solubility and Physical Properties for Gas-Saturated Athabasca Bitumen

Nourozieh

Kariznovi

Abedi

2016

SPE Production &Amp; Operations

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The addition of hydrocarbon or nonhydrocarbon gases to steam can have a beneficial effect on the performance of steam-based processes for recovery of heavy and extraheavy oils. The performance of these newly developed techniques depends on the amount of solvent dissolved in the oil and the variation of oil viscosity with temperature. Thus, full understanding of the quantitative effects of the solvent on heavy-oil viscosity and phase behaviors is crucial for feasibility studies, design, and prediction of fieldscale processes.Thus, the aim of this research is the development of an understanding of the phase behavior of carbon dioxide (CO 2 )/Athabasca-bitumen mixtures. It includes both experimental and modeling studies of solubilities and saturated-liquid densities and viscosities over a wide range of temperatures (up to 200 C), approaching the conditions of in-situ steam processes and pressures up to 6 MPa.Experimental results indicate that the dissolved gas in bitumen leads to a significant oil-viscosity reduction, and the effect is greater at lower temperature and higher pressure. The gas-saturated-bitumen densities change slightly with the dissolution of CO 2 . The modeling results show that the measured solubilities are represented adequately by the modified Peng-Robinson equation of state (Robinson and Peng 1978), with an average absolute relative deviation (AARD) of 7.5%. The saturated-liquid densities are also correlated with equation-of-state and effective-liquid-density approaches, with 0.77 and 0.41% AARDs, respectively. The viscosity data are reasonably matched with the modified Pedersen corresponding state (Pedersen and Fredenslund 1987).

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Section: Prediction Of Liquid Densitiesmentioning

confidence: 99%

Section: Prediction Of Liquid Densitiesmentioning

confidence: 99%

Measurement and Correlation of Solubility and Physical Properties for Gas-Saturated Athabasca Bitumen

Nourozieh

Kariznovi

Abedi

2016

SPE Production &Amp; Operations

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“…Most of them are heavy oils, for which data are in general scarce in literature (Kokal and Sayegh 1993;Yazdani and Maini 2010). Therefore, pseudo data (Merrill and Newley 1993) are generated for MMPs with pure CO 2 and pure C 1 and some three-phase envelopes using 30 components (including 22 pseudo components) based on the CM w/o V (Pedersen and Christensen 2007;Krejbjerg and Pedersen 2006;Pedersen et al 1983Pedersen et al , 1984Pedersen et al , 1989Pedersen et al , 1992Pedersen et al , 2004 as explained in detail in Kumar and Okuno (2012a). Using the CM w/o V, the effects of the number of components on phase behavior predictions diminish when more than 16 components are used (Kumar and Okuno 2012a).…”

Section: Case Studiesmentioning

confidence: 99%

Universal Fluid Characterization Using an EOS Based on Perturbation from n-Alkanes

Kumar

Okuno

2013

Day 3 Wed, October 02, 2013

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Reliability of compositional simulation can depend significantly on the phase behavior model used in the simulation. Characterization of reservoir fluids using a cubic equation of state (EOS) is conducted based on experimental data available. Thermodynamic conditions used in laboratory measurements, however, are only a small part of actual conditions encountered in reservoir processes. Thus, reservoir fluid characterization is performed under unavoidable uncertainties in pressuretemperature-composition (P-T-x) space. The implicit, non-linear relationship between phase behavior predictions and adjustment parameters also makes fluid characterization non-unique and subjective. Although P-T-x space that phase behavior spans is continuous, different characterization methods have been proposed for different types of reservoir fluids.In our previous research, a method was developed for heavy-oil characterization using the Peng-Robinson (PR) EOS with the van der Waals mixing rules without volume shift. Uncertainty issues in heavy-oil characterization were addressed based on the concept of perturbation from n-alkanes (the PnA method). Pseudo components were initially assigned critical parameters that were optimized for n-alkanes in terms of liquid densities and vapor pressures using the PR EOS. The optimized reference values allowed for well-defined directions for perturbation of pseudo components' critical parameters to match available experimental data. The robust regression algorithm required only three perturbation parameters.In this paper, we extend the PnA method to lighter fluids, such as gas condensates, volatile oils, and near-critical fluids. The main novelty of the new PnA method is that it considers proper interrelationship (ψ = a/b 2 ) between the attraction (a) and covolume (b) parameters of pseudo components. The regression algorithm developed in this research controls the trend of the ψ parameter with respect to molecular weight using a fourth adjustment parameter γ. The ψ and γ parameters become more important for characterizing lighter fluids. For extra heavy oils, the new PnA method naturally reduces to the previous PnA method, where γ is zero.Case studies using 77 different reservoir fluids demonstrate the universal applicability, reliability, robustness, and efficiency of the new PnA method. The fluids used consist of 34 heavy and black oils, 12 volatile oils, and 31 gas condensates. Six fluids are near critical among them. The PnA method controls phase behavior predictions monotonically with parameter adjustments and systematically in P-T-x space. This is demonstrated by quantitative prediction of condensation/vaporization behavior of gas condensates and light oils and minimum miscibility pressures for various oil displacements. The PnA method requires no change in the thermodynamic model used; i.e., it can be readily implemented in existing software based on the PR EOS with the van der Waals mixing rules.We also explain how volume-shift parameters affect compositional phase behavior predictions when...

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“…The mixtures in Table 1 were characterized using the procedure of Pedersen et al, (12) which handles hydrocarbon constituents as heavy as C 200 . Methane reference temperatures as low as 23 K were found when trying to apply the corresponding states principle to simulate viscosities for the experimental conditions.…”

Section: Heavy Oil Viscosity Modelmentioning

confidence: 99%

The Corresponding States Viscosity Model Applied to Heavy Oil Systems

Lindeloff¹,

Pedersen²,

Rønningsen

et al. 2004

Journal of Canadian Petroleum Technology

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The corresponding states viscosity model is widely accepted in the petroleum industry for calculating oil and gas viscosities. In its classical form, the model predicts the viscosities of complex mixtures using methane as a reference compound. As a result of the chosen reference compound, the corresponding states model has good predictive capabilities for gases and light oil systems, whereas the predictive performance deteriorates for heavier oil systems. The present work discusses how far the performance of the corresponding states model can be stretched in its classical form with methane as the reference compound. It further outlines a procedure based on a viscosity correlation for stable oil mixtures that may take over when the methane reference temperature becomes too low to apply methane as reference compound. In the temperature region where the new correlation is to take over from the classical corresponding states model, there is a smooth transition between the viscosity results obtained with either method. Therefore, the new correlation can be seen as an extrapolation of the corresponding states method to be applicable to heavy aromatic oil mixtures at relatively low temperature. Introduction Viscosity is a key transport property for sub-surface simulations as well as well design and pipeline and process simulations. A number of correlations for viscosity of petroleum systems exist, ranging from simple ones requiring information on bulk properties, like API gravity and temperature such as the Beggs and Robinson correlation(1), to the more complex ones relying on the composition of the mixture in question. The most popular of the latter type is the method by Jossi et al.(2) which was developed for reservoir fluids by Lohrenz et al.,(3) most often referred to as the Lohrenz-Bray-Clark (LBC) correlation. The LBC correlation is not in general predictive but being a polynomial it can easily be tuned to viscosity data. As it executes rapidly if coded into a computer, it is an obvious choice in reservoir simulation models where CPU time constraints apply. If, on the other hand, no experimental data are available for tuning, there is a great risk of serious miscalculations. Another pitfall with viscosity correlations may occur when tuning the model entirely to stabilized oil viscosity data. In his situation, live oil and gas viscosity predictions from the correlation can become highly unrealistic. For these reasons, the more reliable, but also more complex, corresponding states model is an important tool for the petroleum industry. The corresponding states viscosity model has good predictive capabilities for gases and light oils, whereas the predictive capabilities deteriorate for heavier oil systems. This is fundamentally because methane at the corresponding reference state would be a solid for which no viscosity ata are available. It follows that for a heavy oil system, a heavier reference compound would be more appropriate. A change in reference compound however requires viscosity data in a wide temperature and pressure range for a heavier hydrocarbon, s for example n-decane. Unfortunately, most viscosity data for heavier compounds are measured at atmospheric pressure, and hence the pressure effects cannot be captured properly.

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Cubic Equations of State Applied to HT/HP and Highly Aromatic Fluids

Cited by 73 publications

References 11 publications

Measurement and Correlation of Solubility and Physical Properties for Gas-Saturated Athabasca Bitumen

Measurement and Correlation of Solubility and Physical Properties for Gas-Saturated Athabasca Bitumen

Universal Fluid Characterization Using an EOS Based on Perturbation from n-Alkanes

The Corresponding States Viscosity Model Applied to Heavy Oil Systems

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