Modification of the petroleum system concept:Origins of alkanes and isoprenoids in crude oils:Discussion

摘要

In their recent paper,Collister et al.(2004)presented a statistical analysis of Cio-C28 n-alkane and C_(16)-C_(21)regular isoprenoid distributions of oils and rock extracts from the Timan-Pechora basin.They found that all unaltered to moderately biodegraded samples could be described as mixtures of six end-member compositions that were assigned to five unique biological sources and to one reservoir process(biodegradation).Because the end members appeared to yield no indications of thermal maturation,Collister et al.surmised that these hydrocarbons were generated not from the thermal cracking of kerogen,but from the liquefaction of biopolymers.If this theory is true,our current paradigms of oil generation and source rock potential need to be changed drastically because it suggests that a significant quantity of liquid hydrocarbons can be generated directly from unaltered biological precursors instead of the thermal cracking of kerogen.