Maturation and bulk chemical properties of a suite of solid hydrocarbons

Abstract

In this paper, we present strong correlations of solid hydrocarbon reflectance (SHRo) to vitrinite reflectance (VRo) and bulk chemical properties (aromaticity, Tmax, H/C, etc.). These correlations suggest that, like kerogen in coals and sedimentary rocks, solid hydrocarbons vary systematically during maturation. As a consequence, SHRo is especially useful as a maturity indicator in rocks lacking vitrinite, such as pre-Devonian rocks and many organic-rich marine rocks. Unlike other organic maturationv indicators, the utility of solid hydrocarbons is not limited by botanical evolution, but rather the generative potential of the petroleum system. Solid hydrocarbons, also known as “solid bitumen”, “asphalt”, “dead oil”, “migrabitumen”, and “pyrobitumen”, are genetically defined as solid phase accumulations of predominantly hydrocarbons produced by petroleum generation in source rocks. They may occur over a range of concentrations in outcrop and well samples in all components of petroleum systems. Although accumulations of solid hydrocarbons from exhumed reservoirs are well-reported, the extent and utility of disseminated solid hydrocarbons in shales is less understood. Solid hydrocarbons are found in organic-rich to very lean, mature rocks as a residual product of generation. Disseminated solid hydrocarbons exhibit three optical forms; anisotropic (“coked”), “granular”, and relatively uniform (“homogenous”). Only the “homogenous” solid hydrocarbons are recommended for correlation purposes with other thermal indicators.