Journal of Petroleum Geology, Vol.12, No.1, pp. 103-110, 1989

©Copyright 2000 Scientific Press, Ltd.

COMPARISON OF KEROGEN MATURATION AND ILLITE/SMECTITE COMPOSITION IN DIAGENESIS

B. Velde* and J. Espitalié**

* Laboratoire de Géologie, ER 224 CNRS, Ecole Normale Supérieure, 46 rue d'Ulm, 75230 Paris, France.

** Institut Français du Pétrole. 4 Ave Bois Preau, Rueil Malmaison, 92, France.

Abstract

Kerogen maturation, estimated from pyrolysis Tmax values, is compared with the smectite layer-content of the illite/smectite mineral derived from sediments in six suites from different basins with different ranges of stratigraphic age. The most significant correlations are made when comparing Tmax and estimated percentage kerogen transformation with sample age for the same smectite layer-content (iso-smectite content or stage of clay maturation). The percentage transformation of Type III kerogen and smectite layer-content shows a regular relationship at the end of the clay reaction series (10% smectite content), which includes the oil and gas potential range for sediments in the 200 - 100 MM year age groups. Relations between less mature, more smectitic illite/smectite clay minerals and kerogen maturation are not at present clear.