HR: 1340h
AN: U43C-1384    [Abstracts]
TI: Experimental Fluid-Rock Reactions Along the CO₂ Pathway in Carbonate Host Reservoir.
AU: Luquot, L
EM: luquot@msem.univ-montp2.fr
AF: Laboratoire de Geosciences, Universite Montpellier 2, Place Eugene Bataillon, Montpellier, 34095,
AU: * Gouze, P
EM: gouze@msem.univ-montp2.fr
AF: Laboratoire de Geosciences, Universite Montpellier 2, Place Eugene Bataillon, Montpellier, 34095,
AB: CO₂ sequestration in geologic formations is increasingly being studied as a workable way for limiting CO₂ overload in the atmosphere. Here, we will focus on carbonate rock which represents the large properties the targeted sedimentary reservoirs. The aim of this study is to produce experimental data base for constraining the modelling of CO₂ injection and sequestration. A set of reactive percolation experiments in in-situ-like pressure and temperature conditions (i.e. T=100°C, P=12MPa) are presented. Experiments were designed to quantify reactions occurring near the CO₂ injection zone where the aquifer fluid is saturated with CO₂ and at increasing distances from the injection where the fluid is expected to contain progressively less CO₂ and more divalent cations resulting from the rock dissolution along the fluid pathway. The underlying idea is to obtain experimental control points in space and time corresponding to the transport of the CO₂ in the reservoir during the injection phase, whereas a complete and continuous reproduction of the processes at laboratory scale is obviously unfeasible. The protocol allows measuring changes in porosity and permeability continuously, as well as rock structure using recurrent X-ray microtomography imaging and effluent composition repeatedly. Results show that reactions produce high permeability channels, concomitant loss of integrity of the system close to the injection well, whereas precipitation inducing permeability decrease takes place far from the well. Mass transfers distribution and rate can be associated with the value of the CO₂ partial pressure (P_CO2) and Calcium saturation index (I_Ca) only. Specifically, dissolution is increasingly homogeneous as P_CO2 decreases. Conversely, porosity-permeability relation is well fitted by the simple law k = a \; Φⁿ where n can be related to the pore scale effective Damköhler number (which depend on the inlet P_CO2 and I_Ca) by a simple power law relation. Then, the permeability change can be expressed as a function of the porosity changes by the relation k = a \; Φ^bDa where a and b are constants that are probably fixed by the initial structure of the rock and the reaction type respectively.
DE: 1012 Reactions and phase equilibria (3612, 8412)
DE: 1857 Reservoirs (surface)
DE: 1858 Rocks: chemical properties
DE: 5114 Permeability and porosity
DE: 5139 Transport properties
SC: Union [U]
MN: 2007 Fall Meeting