INDIVIDUAL CHARACTERIZATION OF PETROLEUM FLUID INCLUSIONS (COMPOSITION AND P-T TRAPPING CONDITIONS) BY MICROTHERMOMETRY AND CONFOCAL LASER SCANNING MICROSCOPY: INFERENCES FROM APPLIED THERMODYNAMICS OF OILS

Abstract

This paper proposes a new method to characterize individual oil-bearing fluid inclusions. It uses both the homogenisation temperatures measured by microthermometry, and the degree of gas bubble filling measured by confocal laser scanning microscopy, in conjunction with thermodynamic modelling for describing liquid-gas phase transitions and the volumetric behaviour of hydrocarbon mixtures. It is associated with a two-parameter (α, β) compositional model that describes the wide range of compositions of petroleums. We show that this method can give (1) useful estimations of the compositions and pressure-temperature entrapment conditions of oils in fluid inclusions, and (2) insights into the various processes that have affected these fluids either before entrapment (liquid-gas unmixing, gas leaching, mixing, etc.) or after (leakage, etc.).