Details

Autor(en) / Beteiligte

• Dávila, Gabriela
• Cama, Jordi
• Luquot, Linda
• Soler, Josep M.
• Ayora, Carlos

Titel

Experimental and modeling study of the interaction between a crushed marl caprock and CO2-rich solutions under different pressure and temperature conditions

Ist Teil von

• Chemical geology, 2017-01, Vol.448, p.26-42

Ort / Verlag

Elsevier B.V

Erscheinungsjahr

2017

Link zum Volltext

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Carbon storage is regarded as a potential technology to reduce CO2 emissions. This study is concerned with CO2 storage in a reservoir rock (limestone) which is a deep saline aquifer containing a NaCl− and sulfate-rich groundwater in equilibrium with calcite and gypsum. The reservoir rock is overlain by a very low permeability formation (marls), which acts as a caprock. During and after CO2 injection, the resulting CO2-rich acid solution gave rise to mineral dissolution and precipitation processes. These reactions led to changes in porosity, pore structure and permeability of the caprock and also to the alteration of its CO2 seal capacity. Flow-through experiments using columns filled with three crushed samples (marly limestone, bituminous black shale and marl), which constitute the Hontomín caprock unit, were conducted under different PTotal-pCO2 (atmospheric: 1–10−3.5bar, subcritical: 10–10bar and supercritical: 150–37bar) conditions and T (25 and 60°C) using gypsum-undersaturated and gypsum-equilibrated solutions to evaluate the Hontomín caprock reactivity. 1D reactive transport modeling of the results enabled us (1) to better understand the overall processes that bring about the large dissolution of calcite, minor dissolution of aluminosilicates and the precipitation of gypsum, kaolinite, zeolites and some aluminum and iron oxides and oxyhydroxides and sulfates and (2) to evaluate their implication for the hydrodynamic properties of the caprock. An increase in porosity over the column length, which mostly occurred near the inlet, was calculated. •Experiments and modeling of the marl caprock-CO2-rich solution interaction under different pCO2 conditions•Coupled dissolution of calcite and Si-bearing minerals and precipitation of gypsum increase porosity.•Porosity increase is larger in the presence of sulfate than in its absence.•Calcite dissolution increases by decreasing temperature whereas gypsum precipitation is barely influenced by T.•Mineral dissolution occurs over the column in CO2-rich solutions and at the first contact of the rock in HCl solutions.