Abstract
Correlation between vitrinite reflectance (Ro) and Tmax from Rock-Eval pyrolysis for Japanese argillaceous rocks is investigated using data of 572 samples from 21 wells drilled on land and offshore Japan. The organic matter of samples is predominantly Type III. Therefore the variation of organic matter type has little influence on the correlation between Ro and Tmax The depth variations of the two parameters in each well indicate that the Tmax is less reliable than vitrinite reflectance as a maturity parameter. Tmax data of cuttings are particularly affected by contamination of drilling mud additives. The correlation between vitrinite reflectance and Tmax of Japanese argillaceous rocks is expressed in the following equation based on the data of cores, which are less susceptible to contaminants compared with sidewall cores and cuttings: Tmax(℃)=46×Ro(%)+406.
