The isolation, occurrence and origin of fluorenones in crude oils and rock extracts

A rapid method for the analysis of fluorenones in crude oils and reservoir core extracts based on solid phase extraction and GC–MS is described. A detailed reservoir study involving analysis of both fluids and core extracts was performed and variations in the distributions of fluorenones between reservoir phases are discussed. Concentrations of fluorenones in reservoir core extracts are often very high, which may reflect sorption processes after fluorenone production but in general, fluorenone abundance in flowed oils seems to be sporadic and may be related to sample age and storage history with recent production oils having lower fluorenone concentrations than corresponding older Drill Stem Test oils. While a geochemical origin for fluorenones cannot be eliminated in some settings, we are concerned that these compounds may be frequently formed sporadically as a result of post-sampling oxidation.