Petroleum is very complex and rich in information. Analyses of an individual oil can uncover the chemical signatures of source organisms and their habitats, sediment lithology, thermal history and post-emplacement alteration. Analyses of oils globally reveal much more including aspects of their changing composition through geological time and across conjugate continental margins. GeoMark Research has created a database of the biomarker and isotopic characteristics of 4500 oils varying in age from Precambrian to Neogene. Exploring this database for secular and other trends provides a fascinating insight into biological and environmental evolution as well as a practical tool for determining the origins of oils of unknown provenance. This paper discusses the analytical methodologies needed to make this undertaking successful, some insights gained about the evolution of organic matter through time and a practical application addressing the likely origins of ocean-transported bitumens stranded on Australia's coastlines.