Integrated Approach Coupling a 2-D Basin Model with a 2-D Thermo-Mechanical Model of Lithospheric Processes: Implications to the Hydrocarbon Generation in the Paris Basin

Menetrier, Cedric¹, Antoine Le Solleuz¹, Marcel Elie¹, Luis Martinez¹, Jean Robert Disnar², Cecile Robin³, François Guillocheau³ (1) UMR 7566 G2R UHP Nancy I, Vandoeuvre les Nancy, France (2) ISTO, Orleans, France (3) University of Rennes, Rennes, France

This paper proposes an integrated numerical study to analyse thermal history of sedi­mentary basins by inversion of geological data. This new approach couples a 2D numerical model of hydrocarbon generation with a 2D thermo-mechanical model of the lithosphere using stratigraphic correlations and thermal indicators analysis.

This method is applied to the Paris Basin. In a first step, from a wells study along a W­E cross-section, we deduce i) stratigraphic correlations, and ii) an analysis of thermal indi­cators in westphalian (mainly type III) and mesozoic (mainly type II organic matter) forma­tions. We consider different thermal indicators (Transformation ratios, Vitrinite Reflectance or C31 Hopanes S/R isomerisation ratios) to integrate the whole maturity range observed for the organic matter and to constrain the thermal history.

The numerical approach allows computing surface heat flow variations during time, based on a 2D thermo-mechanical model by inversion of stratigraphic data (Le Solleuz et al., this congress). Knowing the prediction of hydrocarbon generation essentially depends on surface heat flow variations and burial history, we use PetroMod© by inversion of geochem­ical data, to quantify the thermal history and fluid transfers in the Paris Basin.

Then results show the implications on timing of hydrocarbon generation of the Westphalian coals located in the Eastern part of the Paris basin. This model implies an early (Permian) gas generation phase for the deepest formations, whereas hydrocarbon genera­tion in shallow formations is induced by mesozoic sedimentary rates. The differences between this new strategy and other thermal models (timing of hydrocarbon generation) are important.