Phenanthrene and Methylphenanthrene Isomers in Maturity Assessment of Biodegraded Crude Oils (Sakhalin, Russia)

Abstract

This paper is aimed at defining two new advantageous maturation parameters based on distribution and abundance of phenanthrene (P) and methylphenanthrene (MP) isomers in the tricyclic fraction of aromatic hydrocarbons: MPI 3+1/PAI 1 and [2(2-MP+3-MP)+P]/1-MP. The applicability of newly proposed parameters was checked by correlation analysis. Depth of the reservoir rock, diasterane maturation parameter, as well as several typical aromatic fraction maturation parameters were used for this purpose. The examined oils (fourteen samples from nine oil fields of Sakhalin Island, Russia), were of Miocene age and from reservoir rocks of relatively wide range of depths (73-2841 m). All samples represented biodegraded, or mixtures of biodegraded and nonbiodegraded oils [1].