Potential of emission Fourier transform infrared spectroscopy for in situ evaluation of kerogen in source rocks during pyrolysis

Eleven petroleum source rock samples have been examined by Emission Fourier transform infrared spectroscopy (FTIRES) and by Rock-Eval thermal analyses. FTIRES has been used to estimate the amount of C–H aliphatic and C–H aromatic signal lost during thermal treatment at Rock-Eval temperatures. In particular, the loss of signal from 150°C to 300°C has been monitored and compared to the yield of oil obtained over this range by Rock-Eval analysis. Likewise, signal loss between 300–500°C and 500–700°C was monitored. Correlations of FTIRES changes with Rock-Eval pyrolysis derived parameters were not found because FTIRES reflects changes in composition of undistilled material during pyrolysis. However, by relating Rock-Eval and FTIRES derived parameters a source rock quality index can be derived. This index can be useful as a quick routine method for scanning samples to determine if the free oil in the source rock was generated by thermal maturation of the same source rock.