Calculation of the thermodynamic properties at elevated temperatures and pressures of saturated and aromatic high molecular weight solid and liquid hydrocarbons in kerogen, bitumen, petroleum, and other organic matter of biogeochemical interest

To supplement the relatively sparse set of calorimetric data available for the multitude of high molecular weight organic compounds of biogeochemical interest, group additivity algorithms have been developed to estimate heat capacity power function coefficients and the standard molal thermodynamic p roperties at 25 degrees C and 1 bar of high molecular weight compounds in h ydrocarbon source rocks and reservoirs, including crystalline and liquid is oprenoids, steroids, tricyclic diterpenoids, hopanoids, and polynuclear aro matic hydrocarbons. A total of ninety-six group contributions for each coef ficient and property were generated from the thermodynamic properties of lo wer molecular weight reference species for which calorimetric data are avai lable in the literature. These group contributions were then used to comput e corresponding coefficients and properties for similar to 360 representati ve solid and liquid high molecular weight compounds in kerogen, bitumen, an d petroleum for which few or no experimental data are available. The coeffi cients and properties of these high molecular weight compounds are summariz ed in tables, together with those of the groups and reference species from which they were generated. The tabulated heat capacity power function coeff icients and standard molal thermodynamic properties at 25 degrees C and 1 b ar include selected crystalline and liquid regular, irregular and highly br anched isoprenoids, tricyclic diterpanes, 17 alpha(H)- and 17 beta(H)-hopan es, 5 alpha(H), 14 alpha(H)-, 5 beta(H), 14 alpha(H)-, 5 alpha(H), 14 beta( H)-, and 5 beta(H), 14 beta(H)-steranes, double ether-and ester-bonded n-al kanes, and various polynuclear aromatic hydrocarbons, including methylated biphenyls, naphthalenes, phenanthrenes, anthracenes, pyrenes, and chrysenes . However, corresponding coefficients and properties for many more saturate d and unsaturated high molecular weight hydrocarbons can be estimated from the equations of state group additivity algorithms. Calculations of this ki nd permit comprehensive thermodynamic description of the chemical evolution of organic matter with increasing depth in sedimentary basins. Copyright ( C) 1998 Elsevier Science Ltd.