INSITU HIGH-TEMPERATURE ESR MEASUREMENTS FOR KEROGEN MATURATION

Kerogen samples from Middle Miocene mudstone cores in two Japanese exploratory wells have been investigated by an in situ high temperature ESR technique. Anhydrous pyrolysis of the kerogens results in four distinct temperature stages in spin concentration (Ns). Ns increases in the first and third stages and decreases in the second and fourth stages. The trend of Ns for kerogen samples in the middle and end of catagenesis is characterized only by two stages (third and fourth). These data are based on the formation and recombination of free radicals, and have been used to derive parameters related to kerogen maturation and hydrocarbon generation.