Does grain size influence hydrocarbons generation and mesoporosity during artificial thermal maturation of an organic-rich mudstone?

To assess how the grain size/rock fabric of laboratory-matured shale samples impact oil, gas production, and formation pores during laboratory thermal maturation, cores (4.5 mm*1 cm) bulk rock, millimetric equidimensional rock fragments (3*3 mm), fine grind powder (<200 μm) were obtained from an organic-rich mudstone (Kimmeridge Clay Fm. “KCF”, Yorkshire, UK) artificially matured under anhydrous conditions. The composition organic matter (OM), porosity, maturity characterized using nitrogen adsorption, Rock-Eval® VI pyrolysis, GC/TCD (Gas-Chromatography/Thermal Conductivity Detector), GC/MS (Gas Chromatography/Mass Spectrometry). While only a few differences in geochemical porosity exist between powders, greater gap is observed with cores. Probably due to lower surface contact components themselves clay mineral surfaces (which can act as catalyst oil generation) less intense OM degradation processes for use rather than results in: (i) production extractible concentrations; (ii) amounts (C1–C5 CO2); (iii) pore volumes smaller sizes maturation. This preliminary work highlights importance considering being shows that intact (e.g. cores), closer natural conditions, could be more suitable when studying porosity. In comparison previous works, this also demonstrated depending on maturation system used semi-confined, confined) amount hydrocarbons generated differ significantly find their origin different processes.