The Force of Crystallization and Fracture Propagation during In-Situ Carbonation of Peridotite

Abstract

Subsurface mineralization of CO 2 by injection into (hydro-)fractured peridotites has been proposed as a carbon sequestration method. It is envisaged that the expansion in solid volume associated with the mineralization reaction leads to a build-up of stress, resulting in the opening of further fractures. We performed CO 2 -mineralization experiments on simulated fractures in peridotite materials under confined, hydrothermal conditions, to directly measure the induced stresses. Only one of these experiments resulted in the development of a stress, which was less than 5% of the theoretical maximum. We also performed one method control test in which we measured stress development during the hydration of MgO. Based on microstructural observations, as well as XRD and TGA measurements, we infer that, due to pore clogging and grain boundary healing at growing mineral interfaces, the transport of CO 2 , water and solutes into these sites inhibited reaction-related stress development. When grain boundary healing was impeded by the precipitation of silica, a small stress did develop. This implies that when applied to in-situ CO 2 -storage, the mineralization reaction will be limited by transport through clogged fractures, and proceed at a rate that is likely too slow for the process to accommodate the volumes of CO 2 expected for sequestration.

Modeling Porosity Evolution Throughout Reaction‐Induced Fracturing in Rocks With Implications for Serpentinization

“…It was submitted to a triaxial loading in order to reach a predefined isotropic stress state of 30 MPa, a stress value representative of in situ serpentinization reactions (Marcaillou, ). The local mechanical properties were adjusted to fit the behavior of the model to the behavior of the peridotite (Van Noort et al, ). These parameters are listed in Table .…”

“…The alteration of elastic properties and strength of rocks undergoing serpentinization has fundamental implications on the mechanical and seismic properties of the lithosphere and has thus to be studied. Typical values of stiffness, uniaxial tensile strength, cohesive shear strength and other mechanical properties of ultramafic rocks are presented in Table (Van Noort et al, ).…”

Competition Between Crystallization‐Induced Expansion and Creep Compaction During Gypsum Formation, and Implications for Serpentinization

“…Relatively little work has been done to constrain crystallization pressures in these types of situations (see Ghofrani & Plack, 1993;Ostapenko, 1976;Ostapenko & Yaroshenko, 1975;van Noort et al, 2017;Wolterbeek et al, 2017). However, the role of confined crystallization is of primary importance to the dynamics of numerous geophysical processes, including replacement of olivine by serpentinite or magnesite (Kelemen et al, 2011;Kelemen & Hirth, 2012), reaction-induced fracturing (Kuleci et al, 2017;Zhu et al, 2016), and geologic carbon sequestration (Kelemen & Matter, 2008;Matter & Kelemen, 2009).…”

“…Large degrees of serpentinization are commonly observed in the field (Iyer et al, 2008;Macdonald & Fyfe, 1985) and can be reproduced by numerical models of olivine hydration that include fracturing processes (e.g., Malvoisin, Podladchikov, et al, 2017;Rudge et al, 2010). However, only a few experimental studies have observed reaction-induced fracturing during hydration reactions (Kuleci et al, 2017;Zhu et al, 2016) and attempts at measuring reaction-induced stresses due to olivine hydration or carbonation have met with limited success (Malvoisin & Brunet, 2014;van Noort et al, 2017…”

Experimental Investigation of the Pressure of Crystallization of Ca(OH)2: Implications for the Reactive Cracking Process

“…As a result, there is no consensus regarding the nature of deformation due to retrograde metamorphism (e.g., Ghofrani & Plack, 1993;Kuleci et al, 2017;Ostapenko & Yaroshenko, 1975;Skarbek et al, 2018;Van Noort et al, 2017;Wolterbeek et al, 2017;Zhu et al, 2016). Generation of stress due to crystallization has been mostly studied in environments where crystallization occurs within a porous medium whose matrix does not participate in the reaction.…”