PIT (Petroleum Inclusion Thermodynamic): a new modeling tool for the characterization of hydrocarbon fluid inclusions from volumetric and microthermometric measurements

Abstract

A recent technique, the confocal scanning laser microscopy, allows for the accurate measuring of the bubble filling degree (Fv) of oil fluid inclusions as a function of the temperature [Pironon, J., Canals, M., Dubessy, J., Walgenwitz, F., Laplace-Builhe, C., 1998. Volumetric reconstruction of individual fluid inclusions by confocal scanning laser microscopy. Eur. J. Mineral. 10, 1143–1150]. These data, combined with measurements of homogenization temperature (Th), give us new constraints for characterizing individually hydrocarbon fluid inclusions. For this purpose, a new modeling tool, PIT (Petroleum Inclusion Thermodynamic), based on applied thermodynamics of natural oils, has been constructed for interpreting volumetric (Fv) and microthermometric (Th) measurements obtained on hydrocarbon fluid inclusions. The software allows us: (1) to reconstruct the paleo-thermobarometric trapping conditions of oils; (2) to model petroleum inclusion composition; and (3) to understand (Fv–Th) differences among a population of fluid inclusions in terms of various pre- or post-trapping processes (inclusion stretching, oil mixing, liquid/vapor de-mixing, oil leaching by a gas, etc.).