Thermodynamic properties of hydrocarbon liquids at high pressures and temperatures

Conference · Wed Jan 01 00:00:00 EST 1992 · Geological Society of America, Abstracts with Programs; (United States)

OSTI ID:5905979

Aagaard, P ^[1]; Oelkers, E H ^[2]; Helgeson, H C ^[3]

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1. Univ. of Oslo (Norway). Dept. of Geology
2. Univ. Paul Sabatier, Toulouse (France). Lab. de Geochimie
3. Univ. of California, Berkeley, CA (United States). Dept. of Geology and Geophysics

Understanding the organic/inorganic interface in the Earth's crust requires values of the thermodynamic properties of hydrocarbon species in crude oil, coal, and natural gas at elevated temperatures and pressures. Values of the apparent standard partial molal Gibbs free energies and enthalpies of formation and the standard partial molal entropies and heat capacities of these organic species can be computed as a function of temperature at 1 bar using the equations of state adopted by Helgeson et al (1991). The pressure dependence of the thermodynamic properties can be calculated from a modified version of the Parameters From Group Contributions (PFGC) equation of state. To improve the accuracy of these predictions, critical evaluation of high-pressure density experiments reported in the literature was used in the present study to characterize b[sub j] as a function of pressure and temperature. The revised PFGC equation of state permits accurate calculation of the standard partial molal volumes of the major hydrocarbon species in the aliphatic, aromatic, and naphthenic fractions of crude oil, as well as fatty acids, phenols, and naphthenic acids at temperatures and pressures to 500 C and 5 kbar. Combining the revised PFGC equation of state and parameters with the standard partial molal properties of these species at one bar and those of aqueous species and minerals permits calculation of the apparent standard partial molal Gibbs Free energies of reaction, and thus equilibrium constants for a wide variety of chemical equilibria among organic liquids, solids, and gases, aqueous species, and minerals at temperatures and pressures characteristic of both diagenetic and low-grade metamorphic processes in the Earth's crust.

• OSTI ID: 5905979
• Report Number(s): CONF-921058-; CODEN: GAAPBC
• Journal Information: Geological Society of America, Abstracts with Programs; (United States), Vol. 24:7; Conference: 1992 annual meeting of the Geological Society of America (GSA), Cincinnati, OH (United States), 26-29 Oct 1992; ISSN 0016-7592
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
03 NATURAL GAS
01 COAL, LIGNITE, AND PEAT
COAL
THERMODYNAMIC PROPERTIES
NATURAL GAS
PETROLEUM
CONTINENTAL CRUST
DIAGENESIS
ENTROPY
EQUATIONS OF STATE
FORMATION FREE ENERGY
FREE ENTHALPY
METAMORPHISM
RESERVOIR PRESSURE
RESERVOIR TEMPERATURE
SPECIFIC HEAT
CARBONACEOUS MATERIALS
EARTH CRUST
ENERGY
ENERGY SOURCES
EQUATIONS
FLUIDS
FOSSIL FUELS
FREE ENERGY
FUEL GAS
FUELS
GAS FUELS
GASES
MATERIALS
PHYSICAL PROPERTIES
023000* - Petroleum- Properties & Composition
033000 - Natural Gas- Properties & Composition
010600 - Coal
Lignite
& Peat- Properties & Composition