Techniques and concepts of oil-source rock correlations have developed considerably over the past four decades, with work by Hunt in the Uinta basin (1950s) and Williams and Dow in the Williston basin (1970s) shaping our present-day approach. An oil-source rock correlation is a causal relationship between an oil and its mature source rock(s) that is required by the constraints of the petroleum system, which are both chemical (distinctive organic facies) and geologic (lithology, subsidence rate, time of generation, structure). Correlation techniques include bulk methods (compositional fractionation, elemental composition, and isotope ratios) and molecular analyses (biomarkers and their thermal fragments). A successful oil-source rock correlation requires a distinc ion between genetic and nongenetic oil composition properties. Carbon isotope ratios and specific molecular characteristics are the best correlation parameters available.

Three published oil-source rock correlations are presented as case studies. The Black Creek basin in Alberta contains oil in Middle Devonian reservoir rock that originated from underlying and overlying carbonate-evaporite sequences. Although this correlation is chemically defensible, serious migration obstacles exist. The second case addresses the origin of the Beatrice oil from Inner Moray Firth field, offshore Scotland. While analytical results partially overlap, it is apparent that philosophical differences have led to different conclusions by two research groups. The oils of the Cook Inlet basin in Alaska comprise the third case, in which it is shown that rudimentary isotope and biomarker data can help resolve a dispute about the source rock's age (Cenozoic versus Mesozoic).

Future correlation success depends on continuing developments in analytical technology. Whole-oil and whole-rock analysis, using medium- to high-resolution mass spectrometry coupled with pyrolysis, will provide rapid and detailed hydrocarbon compositional data. Available technology will be applied to the development of nonhydrocarbon correlation methods. Further development of gas chromatography-carbon isotope mass spectrometry promises to revolutionize our understanding of petroleum geochemistry and correlation science.