STANDARD PARTIAL MOLAL PROPERTIES OF AQUEOUS ALKYLPHENOLS AT HIGH-PRESSURES AND TEMPERATURES

Potential influences on the distribution of alkylphenols in oilfield w aters include simple partitioning between oil, water, and solid phases , generation of alkylphenols during kerogen maturation in source rocks , and reactions at the oil-water interface in the oil reservoir. Asses sment of whether reactions at the oil-water interface influence phenol distributions in basinal aqueous waters requires thermodynamic proper ties of the aqueous alkylphenols. In this study we have calculated sta ndard partial molal thermodynamic properties of aqueous phenol and cre sols at 25 degrees C and estimated standard partial molal thermodynami c properties of aqueous xylenols at 25 degrees C. These thermodynamic properties (Gibbs free energy, enthalpy, entropy, heat capacity, and v olume) together with estimated coefficients for the revised Helgeson-K irkham-Flowers (HKF) equations of state allow prediction of thermodyna mic properties of reactions involving these species at high temperatur es and pressures. Computed logarithmic equilibrium constants (log K) f or hydration reactions involving alkylphenol are in close agreement wi th log K values calculated from published experimental data (Dohnal an d Fenclova, 1995). Resulting thermodynamic properties may be used toge ther with analytical results, to assess whether metastable equilibrium is a major influence on the abundance and distribution of alkylphenol s in petroleum and associated water. Copyright (C) 1997 Elsevier Scien ce Ltd.