Application of higher diamondoids in hydrocarbon mudrock systems

Diamondoids are ultra-stable geochemical tools applicable to both unconventional and conventional petroleum system analysis. Unlike classic geochemical parameters such as biomarkers, diamondoid stability to geological conditions makes them an ideal tool for deciphering petroleum generation, migration, and accumulation in the subsurface. A collection of hydrocarbon fluid samples and rock extracts were investigated using gas-chromatography triple quadrupole mass-spectrometry techniques for quantitative extended diamondoid analysis (QEDA). Applications of higher diamondoids shown here include: 1) identifying mixing of hydrocarbons having various thermal maturities in the STACK play of Oklahoma, 2) correlating high-maturity fluids to source-rocks in the Permian Basin of Texas, and 3) allocating unconventional petroleum production from the Eagle Ford Formation of Texas through time-series diamondoid analysis. Identifying sweet-spots and allocating produced hydrocarbons are crucial requirements for successful exploitation of unconventional hydrocarbon mudrock systems. Since produced fluids within the most economically successful unconventional reservoirs are at a high thermal maturity level, correlation and allocation of oils to various zones can be difficult. One reason is that classical biomarkers typically used for correlation are generally absent or in low concentrations. Here we show that the ultra-stable diamondoids provide a novel technique to fingerprint fluids in both unconventional and highly mature conventional plays.