Biomarkers: Review And Application To The Eagle Ford Shale Formation

Abstract

Biomarkers have become an integral part of oil exploration. Gas Chromatography (-Mass Spectrometry) was performed to an oil sample to acquire biomarkers from the sample.The presence, lack of, or abundance of a given compound (or biomarker) in the geochemicalresults of an oil sample depict(s) a property or properties of the source rock and the oil. Forexample, the abundance of pristane and lack of phytane in an oil sample are characteristic ofshale source rock, and the results from the Eagle Ford shale formation show a high pristane tophytane ratio.The Eagle Ford shale formation is cretaceous in age; the presence and absence ofcertain biomarkers like oleanane suggest age ranges. The oil sample tested from the EagleFord shale formation support a source rock from the cretaceous period. The results from theEagle Ford shale formation also suggest the thermal maturity of oil samples tested. The EagleFord shale formation produces both gas and oil. This unique property ensures that thebiomarkers detected can be used to study thermal maturity. The results from the Eagle Fordshale formation show a thermal maturity that is between peak and late stages of oil generationwhich supports continued exploration from the reservoir of the oil sample.Results are affected by many variables; therefore, there will be considerable variationsin the ensuing interpretations. The use of multiple biomarkers in the results from the Eagle Fordshale formation and comparing and contrasting those results with other available results willproduce more accurate conclusions.