Extended Data Fig. 3: Hydrocarbon isotopic composition in the Olla (blue circles) and Nebo-Hemphill (orange triangles) oil fields.
From: Rapid microbial methanogenesis during CO2 storage in hydrocarbon reservoirs
a, Comparison of δ13C-CH4 and δD-CH4, with typical CH4 provenances after Whiticar93. One standard deviation error bars are within symbol size. In isolation, the Olla samples (blue circles, this study; unfilled circles, from ref. 10) are consistent with a mainly thermogenic origin, whereas Nebo-Hemphill (orange triangles, this study; unfilled triangles, from ref. 10) appears to be a microbial-thermogenic mix. Clumped isotopologues nevertheless provide clear evidence that the Olla CH4 is microbial in origin (Fig. 3). b, Plot of δ13C of Cn versus 1/Cn variation in natural gases92. One standard deviation error bars are within symbol size. Both the Olla (blue circles) and Nebo-Hemphill (orange triangles) fields show an enrichment in their isotopic signature especially in propane; however, this is most pronounced within the Olla Oil Field.
