The fluorescence alteration of multiple macerals technique for assessment of thermal maturity and the suppression of vitrinite reflectance.

Vitrinite reflectance is a very important thermal maturity indicator in petroleum exploration, but there are two major problems: one is the identification of vitrinite in dispersed organic matter and the other is the suppression or enhancement of vitrinite reflectance. It can be extremely difficult to correctly identify minute vitrinite grains in shapes using conventional microscopy. Even if the vitrinite identification is accurate, however, perhydrous compositions will lead to suppression of measured vitrinite reflectance and subhydrous compositions to enhancement. The fluorescence alteration of multiple macerals (FAMM) technique has been developed at CSIRO Petroleum in Australia to overcome these problems. The main advantages of the FAMM technique are 1) the occurrence and amount of suppression or enhancement of vitrinite reflectance are indicated, 2) identification of specific macerals is commonly not necessary for the analyses, 3) rocks containing very rare or no vitrinite can generally be measured, providing that a suite of other macerals are present and 4) problems of contamination and cavings can be resolved. Thermal maturity measurements with the FAMM technique have been done on more than 2, 500 samples comprising Paleozoic to Tertiary coals and petroleum source rocks from around the world. Application of the FAMM technique to Japanese source rocks can help develop petroleumexploration in Japan.