Experimental observations of fracture dissolution: The role of Peclet number on evolving aperture variability

a b s t r a c tHere we develop analytically the formulas for effective permeability in several configurations using the closed-form description of tree networks designed to provide flow access. The objective was to find the relation between the permeability and porosity of tree-shaped fissures. We found the effect of the fracture size on the permeability for fixed number of bifurcation and the results showed that the permeability of the fracture network increased rapidly with the size of the fracture. Next, we found a relation between the Reservoir Quality Index (RQI) and the porosity of the fracture. The results in this paper have been validated by comparison with experimental and numerical results. We show that the permeability formulas do not vary much from one tree design to the next, suggesting that similar formulas may apply to naturally fissured porous media with unknown precise details, which occur in natural reservoirs.

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“…[20]. Our results also agree with the numerical simulation and experimental results reported by several other authors [18,[21][22][23][24].…”

Section: Discussionsupporting

confidence: 83%

The robustness of the permeability of constructal tree-shaped fissures

Alalaimi

Lorente

Wechsatol

et al. 2015

International Journal of Heat and Mass Transfer

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“…In this regime a dissolution or precipitation front typically develops. The reaction front is often unstable in the dissolution case and leads to fingered dissolution channels, as documented in previous work on fractures [e.g., Hanna and Rajaram, 1998;Durham et al, 2001;Detwiler et al, 2003;Szymczak and Ladd, 2004;Detwiler and Rajaram, 2007]. Natural spatial variations in fracture apertures aid the initiation of unstable finger growth [Cheung and Rajaram, 2002].…”

Section: Introductionmentioning

confidence: 87%

Alteration of fractures by precipitation and dissolution in gradient reaction environments: Computational results and stochastic analysis

Chaudhuri

Rajaram

Viswanathan

2008

Water Resources Research

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[1] Precipitation and dissolution reactions within fractures alter apertures, which in turn affects their flow and transport properties. Different aperture alteration patterns occur in different flow and reaction regimes, and they are also influenced by preferential flow resulting from spatial variations in the aperture. We consider the alteration of variable-aperture fractures in gradient reaction regimes, where fluids are in chemical equilibrium with a mineral everywhere but precipitation and dissolution are driven by solubility gradients associated with temperature variations. The temperature field is defined by a geothermal gradient corresponding to a conduction-dominated heat transfer regime. Monte Carlo simulations on computer-generated aperture fields vividly illustrate pattern formation resulting from two-way feedback between fluid flow and reactive alteration. In dissolution-controlled systems, distinct dissolution channels develop along the dominant flow direction, while elongated precipitate bodies form perpendicular to the mean flow direction in precipitation-controlled systems. Aperture variability accelerates the increase and decrease of effective transmissivity by dissolution and precipitation, respectively. The dominance of precipitation versus dissolution is determined by the angle between the mean hydraulic gradient and solubility/temperature gradient. Development of pronounced anisotropy with oriented elongate features is the key feature of aperture alteration in gradient reaction regimes. A stochastic analysis is developed, which consistently predicts general trends in the aperture field during reactive alteration, including the mean, variance, and spatial covariance structure. Our results are relevant to understanding the long-term diagenetic evolution of fractures in conduction-dominated heat transfer regimes and related problems such as emplacement of ocean bed methane hydrates.

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“…Thus, solute transport in the fracture was controlled by advection in all experiments (e.g., Detwiler et al, 2000) regardless of the composition of the solutions. Earlier studies show a certain correlation between distinct dissolution patterns in fractured cores and Pe numbers (Detwiler et al, 2003;Szymczak and Ladd, 2009;Elkhoury et al, 2013;Garcia-Rios et al, 2015). Elkhoury et al (2013) reported that at low Pe, development of dissolution instabilities in fractured vuggy limestone cores led to face dissolution, intermediate Pe gave rise to large-scale channels, and a high Pe regime led to uniform dissolution along the fracture.…”

Section: Tablementioning

confidence: 99%

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

Dávila

Luquot

Soler

et al. 2016

International Journal of Greenhouse Gas Control

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Please cite this article in press as: Dávila, G., et al., Interaction between a fractured marl caprock and CO 2 -rich sulfate solution under supercritical CO 2 conditions. Int. J. Greenhouse Gas Control (2015), http://dx.doi.org/10.1016/j.ijggc.2015.11.005 Geological CO 2 sequestration at pilot-plant scale will be developed at Hontomín (Spain). CO 2 will be injected into a limestone reservoir that contains a NaCl-and sulfate-rich groundwater in equilibrium with calcite and gypsum. The caprock site is composed of marl. The present study seeks to evaluate the interaction between the Hontomín marl and CO 2 -rich sulfate solutions under supercritical CO 2 conditions (P Total = 150 bar, pCO 2 = 61 bar and T = 60 • C). Flow-through percolation experiments were performed using artificially fractured cores to elucidate (i) the role of the composition of the injected solutions (S-free and S-rich solutions) and (ii) the effect of the flow rate (0.2, 1 and 60 mL h −1 ) on fracture permeability. Major dissolution of calcite (S-free and S-rich solutions) and precipitation of gypsum (S-rich solution) together with minor dissolution of the silicate minerals contributed to the formation of an altered skeleton-like zone (mainly made up of unreacted clays) along the fracture walls. Dissolution patterns changed from face dissolution to wormhole formation and uniform dissolution with increasing Peclet numbers. ARTICLE IN PRESSIn S-free experiments, fracture permeability did not significantly change regardless of the flow rate despite the fact that a large amount of calcite dissolved. In S-rich solution experiments, fracture permeability decreased under slow flow rates (0.2 and 1 mL h −1 ) because of gypsum precipitation that sealed the fracture. At the highest flow rate (60 mL h −1 ), fracture permeability increased because calcite dissolution predominated over gypsum precipitation.

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Experimental observations of fracture dissolution: The role of Peclet number on evolving aperture variability

Cited by 115 publications

References 10 publications

The robustness of the permeability of constructal tree-shaped fissures

The robustness of the permeability of constructal tree-shaped fissures

Alteration of fractures by precipitation and dissolution in gradient reaction environments: Computational results and stochastic analysis

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

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