Three common source rock evaluation errors made by geologists during prospect or play appraisals

Abstract Geologists are frequently called on to evaluate the source rocks associated with their exploration prospects or plays. The three most common questions asked and answered about the source rock during project reviews are What's the total organic carbon (TOC)?, What kerogen type does Rock-Eval indicate?, and What maturity level does the vitrinite reflectance data point to? The answers to these seemingly innocuous questions may, in fact, be providing a false sense of security about the source rock in question. Understanding how this line of questioning can lead you astray and make you the victim of the TOC myth (“If I have high TOC, I have a good source rock.”), the Rock-Eval fallacy (“The Rock-Eval data tell me what kind of kerogen is in my source rock.”), and the vitrinite reflectance deficiency (“Vitrinite reflectance will tell me if my source rock is generating.”) is important. Some of the solutions to these problems include fully integrating TOC and Rock-Eval data, supplementing Rock-Eval data with pyrolysis-gas chromatography, and using burial history diagrams to help interpret vitrinite reflectance.