Stability of Na-, K-, and Ca-Montmorillonite at High Temperatures and Pressures:  A Monte Carlo Simulation

Pablo, Liberto de; Chávez, M. Lourdes; Pablo, Juan J. de

doi:10.1021/la051334a

Cited by 36 publications

(17 citation statements)

References 56 publications

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“…Thus, Odriozola & Guevara-Rodríguez (2004), using Monte Carlo (MC) and molecular dynamics (MD) computer simulations, concluded that where the number of water molecules per clay sheet was~40 in the simulation box, then the one-layer hydrate of Namontmorillonite yielding a basal spacing of 12.5 Å was stable to a depth of 6 km, corresponding to a temperature and pressure of 180ºC and 90 MPa respectively. Similar results for Na-montmorillonite were also obtained by de Pablo et al (2005) who also investigated the stability of the hydrates of Kand Ca-montmorillonite using MC simulation. It was found that the one-layer hydrates of Na-, Kand Ca-montmorillonites were stable at all temperatures (up to~200ºC) and pressures (up tõ 100 MPa) encountered to a depth of~6.7 km, assuming a normal geothermal (30ºC/km) and lithostatic (15 MPa/km) gradient.…”

Section: Nature Of Water In Clays and Shalessupporting

confidence: 80%

“…It may be argued though that even if osmotic swelling does not occur under basin conditions, the more limited crystalline swelling of smectites may still be a major mechanism in shale instability. If, however, the computer simulations of de Pablo et al (2005) concerning the arrangement of water and Na, Ca and K cations in the interlayer space of montmorillonite under basin conditions represent reality, then the one-layer hydrate for all these cations will persist stably at the temperatures and pressures prevailing to a depth of~6.7 km. It is difficult to see therefore that exchange of interlayer Na cations in the interlayer space of smectitic clays for K or Ca cations in the drilling fluid will necessarily involve a volumetric decrease of the smectite and a reduction of swelling pressure.…”

Section: Smectitic Shalesmentioning

confidence: 99%

“…Current explanations of the relationship between clay mineralogy and shale instability emphasize volume expansion following osmotic swelling of the interlamellar space of Na-smectitic clays as the primary failure mechanism. Evidently, this mechanism cannot account for the instability of illitic or kaolinitic shales and it is not at all certain that it is necessarily applicable to all smectitic shales, bearing in mind the lack of data showing the reality of osmotic swelling under basin conditions, as well as the apparent stability of the one-layer hydrates of Na, K and Ca smectites to a depth of 6.7 km as adduced by MD computer simulations (de Pablo et al, 2005). An alternative scenario for the failure of smectitic and illitic shales envisages a mechanism related to overlap of the DDL associated with the charged external surfaces of the clay minerals exposed in opposing walls of micro-and meso-pores of the shale, thus leading to a build up of pore/hydration pressure.…”

Section: O N C L U S I O N Smentioning

confidence: 99%

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Clay mineralogy and shale instability: an alternative conceptual analysis

Wilson

Wilson²

2014

Clay miner.

130

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The instability of shales in drilled formations leads to serious operational problems with major economic consequences for petroleum exploration and production. It is generally agreed that the nature of the clay minerals in shale formations is a primary causative factor leading to their instability, although the exact mechanism involved is more debateable. Currently, the principal cause of shale instability is considered to be volume expansion following the osmotic swelling of Nasmectite. However, illitic and kaolinitic shales may also be unstable, so that interlayer expansion cannot therefore be considered as a universal causative mechanism of shale instability. This review considers alternative scenarios of shale instability where the major clay minerals are smectite, illite, mixed-layer illite-smectite (I/S) and kaolinite respectively. The influence of interacting factors that relate to shale clay mineralogy such as texture, structure and fabric are discussed, as are the pore size distribution and the nature of water in clays and shales and how these change with increasing depth of burial. It is found from the literature that the thickness of the diffuse double layer (DDL) of the aqueous solutions associated with the charged external surfaces of clay minerals is probably of the same order or even thicker than the sizes of a significant proportion of the pores found in shales. In these circumstances, overlap of the DDLs associated with exposed outer surfaces of clay minerals on opposing sides of micropores (<2 nm in diameter) and mesopores (2–50 nm in diameter) in a lithostatically compressed shale would bring about electrostatic repulsion and lead to increased pore/ hydration pressure in smectitic, illitic and even kaolinitic shales. This pressure would be inhibited by the use of more concentrated K-based fluids which effectively shrink the thickness of the DDL towards the clay mineral surfaces in the pore walls. The use of soluble polymers would also encapsulate these clay mineral surfaces and so inhibit their hydration. In this scenario, the locus of action with respect to shale instability and its inhibition is moved from the interlamellar space of the smectitic clays to the charged external surfaces of the various clay minerals bounding the walls of the shale pores.

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Section: Nature Of Water In Clays and Shalessupporting

confidence: 80%

Section: Smectitic Shalesmentioning

confidence: 99%

Section: O N C L U S I O N Smentioning

confidence: 99%

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Clay mineralogy and shale instability: an alternative conceptual analysis

Wilson

Wilson²

2014

Clay miner.

130

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“…This would be surprising and contrary to observations of a significant increase in Xray basal spacing on wetting Ca-montmorillonite [33,38]. There is, however, not universal agreement on this issue as some numerical simulations would indicate [39].These simulations, however, were focused on stability of Ca-montmorillonite at high temperatures and pressures.…”

Section: Mass Change Isothermsmentioning

confidence: 76%

Dimensional change and elastic behavior of layered silicates and Portland cement paste

Beaudoin

Raki

Alizadeh

et al. 2010

Cement and Concrete Composites

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/npsi/ctrl?lang=en http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/ctrl?lang=fr Access and use of this website and the material on it are subject to the Terms and Conditions set forth at http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/jsp/nparc_cp.jsp?lang=en NRC Publications Archive Archives des publications du CNRCThis publication could be one of several versions: author's original, accepted manuscript or the publisher's version. / La version de cette publication peut être l'une des suivantes : la version prépublication de l'auteur, la version acceptée du manuscrit ou la version de l'éditeur. For the publisher's version, please access the DOI link below./ Pour consulter la version de l'éditeur, utilisez le lien DOI ci-dessous.http://dx.doi.org/10. 1016/j.cemconcomp.2009.09.004 Cement and Concrete Composites, 31, 9, p. 34, 2009-09-01 Dimensional change and elastic behaviour of layered silicates and Portland cement paste Beaudoin, J. J.; Raki, L.; Alizadeh, R.; Mitchell, L. D. ABSTRACTThe role of water in hydrated Portland cement paste (hpc) is germane to understanding the nature of nanostructure -property relationships of the material. The irreversible dimensional changes of hpc and phase pure C-S-H that occur on wetting and drying are dissimilar to those observed for other silicate minerals of interest to cement science. This irreversibility in hpc is also observed for the modulus of elasticity parameter. Length change, mass change and modulus of elasticity isotherms (including drying-wetting cycles) were determined for specimens of hpc, Camontmorillonite and 1.4 nm tobermorite. Length change and modulus of elasticity versus mass loss curves were also obtained for phase pure C-S-H (C/S= 0.8,1.0 and 1.5). All the isotherms exhibit significant irreversible behaviour. Similarities and differences in the nature and character of the isotherms and the relevance of the C-S-H data are discussed. Inferences are made with respect to the nanostructural nature of hpc, its dimensional response in aqueous media and the correspondence in behaviour of synthetic C-S-H and that formed in hpc. It is apparent that hpc has unique characteristics that are responsible for stability.

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“…Skipper et al, 1991Skipper et al, , 1995aSkipper et al, ,b, 2006Smith, 1998;Smith et al, 2006), and the origin of clay swelling and its dependency on pressure, temperature, and chemical potential (de Pablo et al, 2004(de Pablo et al, , 2005Smith et al, 2004Smith et al, , 2006. In contrast, little has been done to produce a macroscopic thermodynamic model of fluid-rock interactions that reproduces the discontinuities of volume and amount of water expelled during dehydration of clay as a function of pressure and temperature.…”

Section: Introductionmentioning

confidence: 99%