Numerical modeling of fluid-rock chemical interactions during CO2 saturated water injection into a sandstone reservoir, using the MARTHE-REACT code.

Géraldine Picot-Colbeaux (1) , Marie Pettenati (1) , Dominique Thiéry (1) , Christophe Kervévan (1) , Laurent André (1) , Mohamed Azaroual (1)

1 BRGM - Bureau de Recherches Géologiques et Minières (BRGM)

This study describes the numerical modeling of fluid-rock chemical interactions during CO2-saturated water injection into a sandstone reservoir, using the MARTHE-REACT code (Thiéry et al., 2009, presented in the same TOUGH symposium). The reservoir is modeled in a 2D radial geometry with a thickness of 100 m, divided into three horizontal layers. The layers are characterized by contrasting hydrodynamic properties (porosity between 4 to 7%, permeability between 2×10-16m2 and 2.3×10-15m2), but all layers initially contain the same material (mineralogical assemblage and water composition). CO2-saturated water is injected vertically over the entire thickness of the reservoir. The simulation results confirm the high reactivity of CO2-saturated water with respect to carbonate and sulphate minerals, which are totally dissolved in the water-saturated zone of the near-well field. Reactions occur to a larger extent in the upper layer, where the permeability is higher. Dissolution of calcite, dolomite, and anhydrite induces some pH buffering and a significant increase in porosity, reaching 41% in the first few meters of the water-saturated zone after ten years. Just behind the dissolution front, one can observe precipitation of dolomite, kaolinite, and quartz. Albite dissolution presents the first step in destabilization of the alumino-silicates. This can be explained by the slow kinetics of alumino-silicate mineral dissolution compared to the faster kinetics of carbonates. Consequently, the porosity evolution of the reservoir is essentially constrained by the magnitude of carbonate- and sulphate-mineral dissolution-precipitation reactions. This study is a first step in the assessment of CO2-saturated water leakage from the reservoir to the surface in a sedimentary basin, where physical-functionality approaches implemented in the MARTHE simulator are essential for modeling complex hydrodynamic systems (supporting the link between hydrogeology and hydrology, including, for instance, mass exchanges with the atmosphere and river subsystems).

Domaines: Hydrologie; Milieux et Changements globaux

Géraldine Picot-Colbeaux, Marie Pettenati, Dominique Thiéry, Christophe Kervévan, Laurent André, et al.. Numerical modeling of fluid-rock chemical interactions during CO2 saturated water injection into a sandstone reservoir, using the MARTHE-REACT code.. Proceedings of the TOUGH Symposium, 2009, Sep 2009, Berkeley (California), United States. pp. 80-87. ⟨hal-01073955⟩