Oil-Source Correlation

Oil-source correlation, as the name would suggest, involves testing the degree of similarity between an oil sample (either a test sample or hydrocarbons extracted from a carrier/reservoir rock) with a know source rock. The process primarily employs the comparison of high resolution fingerprints (GC and GC-MS (biomarkers)) and stable isotope data. Invariably, the correlation has to be informed rather than just a visual or statistical comparison of fingerprints.

Source rock samples are typically only available from wells drilled on structural highs and the level of thermal maturity is often fairly low. The oils on the other hand have been generated from deeper source rocks lying within the main oil window. The associated differences in maturity can significantly change the biomarker distributions, and to a lesser extent the isotopic values. These differences must be taken into account when performing oil-source correlation.

There are however a whole host of source diagnostic biomarkers (and related ratios) that persist through the oil window. Identification of such compounds (e.g. oleanane, gammacerane, bisnorhopane) in both oil and source rock can provide strong evidence of a correlation.

Where possible, oil-source correlation should be performed and interpreted in contect of other regional petroleum system knowledge gained from maturity modelling and regional prospect evaluation (or at least some knowledge of kitchen maturity).