Critical considerations when assessing hydrocarbon plays using Rock-Eval pyrolysis and organic petrology data: Data quality revisited

Abstract

The dramatic increase in exploration for unconventional hydrocarbon resources has inherently fuelled the need for new source-rock geochemical data. The need for new data comes along with an increasing number of new users, many of whom do not possess the background to interpret accurately and evaluate the quality of data sets generated by different geochemical screening techniques (e.g., Rock-Eval pyrolysis, vitrinite reflectance). Here, datasets from Rock-Eval pyrolysis, vitrinite reflectance, and LECO TOC analyses are scrutinized and compared to show how failing to recognize good vs. bad datasets can dramatically change interpretations during prospect or play appraisals. Detector saturation, contamination of the sample with drilling fluid, and suppression of both Tmax and vitrinite reflectance, are examples of complications that could compromise the validity of the results and the play or prospect reviews derived from them. In addition, misconceptions such as: “LECO TOC is better than Rock-Eval 6 TOC”, expressed by many users, are a consequence of the lack of understanding of how different screening techniques and instrumentation work. A solid understanding of these pitfalls and limitations can provide inexperienced geoscientists and engineers with the required support to improve risk maps for hydrocarbon-charge analysis and source-rock evaluations, when using classic guidelines for interpreting results.