Impact of coating development on the hydraulic and transport properties in argillaceous limestone fracture

Abstract

[1] Results are reported for an acidic water flow-through experiment conducted in a fractured argillaceous limestone sample (73% carbonates). The change in fracture geometry and related parameters is reported for six data sets obtained from synchrotron X-ray microtomography experiments. High-resolution three-dimensional images of the sample allowed quantification of the changes in fracture morphology at a spatial resolution of 6 mm. Mineral mass loss and permeability changes in the sample were also determined. Several physico-chemical phenomena were identified during the experiment. Initial smooth fracture surfaces evolved rapidly toward rough surfaces with uneven clay coverage due to the preferential dissolution of carbonate minerals compared to clay minerals whose dissolution rate is about 10 6 slower. A microporous clay coating progressively developed at the fluid-rock interface during heterogeneous dissolution of the fracture, while the global dissolution rate of the fracture walls exponentially decreased. The increase in surface roughness and the presumed reorganization of clays caused a progressive reduction in permeability. During the last flow-through stage, a large decrease in sample permeability was attributed to the large removal of clay particles; this process was responsible for a dramatic collapse of the fracture walls near the sample inlet and led to the development of preferential flow pathways. The development of the clay coating also acted as a barrier to flow and mass transfer between calcite grains and bulk solution and affected transport processes within the fracture.Citation: Noiriel, C., B. Madé, and P. Gouze (2007), Impact of coating development on the hydraulic and transport properties in argillaceous limestone fracture, Water Resour. Res., 43, W09406,

Geologic carbon storage is unlikely to trigger large earthquakes and reactivate faults through which CO2could leak

“…Moreover, a self-healing mechanism that prevents CO 2 leakage has been observed in argillaceous limestones (88). We conjecture that these mechanisms, together with increased buoyancy, may explain why CO 2 natural analogs often leak at shallow depths (less than 700 m, where CO 2 is gaseous), but deep natural CO 2 deposits rarely do (89).…”

Interaction between a fractured marl caprock and CO2-rich sulfate solution under supercritical CO2 conditions

“…Likewise, re-activation of micro cracks plays an important role in the flow of CO 2 (Angeli et al, 2009). Ellis et al (2011a,b) observed that the low content of clay minerals, compared with those in samples used by Noiriel et al (2007), Andreani et al (2008) and Angeli et al (2009), prevents the formation of a continuous clay coating along the fracture. Moreover, local heterogeneity exerts strong control over the location of preferential pathways at the microscale (Smith et al, 2013).…”

“…Research into the interaction between the caprock and CO 2 -rich brine through potential leakage pathways is of paramount importance in order to evaluate caprock sealing capacity (Kaszuba et al, 2005;Noiriel et al, 2007;Andreani et al, 2008;Busch et al, 2008;Hangx et al, 2010;Ellis et al, 2011a,b;Berrezueta et al, 2013;Smith et al, 2013). Acidified CO 2 -rich brines may react with caprock minerals that are susceptible to dissolution, releasing ions into the solution that could lead to mineral precipitation (Knauss et al, 1993;Brady and Carroll, 1994;Pokrovsky et al, 2009;Hellmann et al, 2010;Smith and Carroll, 2014).…”

“…In these experiments, core and fractured core samples made up of marl, shale, limestone or evaporite rocks were used (Noiriel et al, 2007;Andreani et al, 2008;Angeli et al, 2009;Berrezueta et al, 2013;Ellis et al, 2011a,b;Deng et al, 2013;Smith et al, 2013). Other mineral alterations including reorganization of clay minerals in the fracture and an altered layer on the fracture surface led to variations in fracture permeability (Noiriel et al, 2007;Andreani et al, 2008).…”

Quantifying fracture geometry with X-ray tomography: Technique of Iterative Local Thresholding (TILT) for 3D image segmentation

“…Over the past two decades, X-ray computed tomography (xCT) has become a valuable tool for 3D visualization and characterization of geological specimens [1][2][3][4][5][6][7][8][9], including fracture geometries [10][11][12][13][14][15][16][17][18][19][20][21], pore networks [22][23][24][25][26][27][28][29][30][31], crystal sizes [32,33], and mineral phases [3,[34][35][36][37][38][39]. xCT imaging is indispensable for non-destructive observation of geometry of fractures, which is important because fractures provide preferential flow conduits and often dominate mass transfer in geological materials.…”