Effect of medium heterogeneities on reactive dissolution of carbonates

Kalia, Nitika; Balakotaiah, Vemuri

doi:10.1016/j.ces.2008.10.026

Cited by 194 publications

(115 citation statements)

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“…This occurs in viscous fingering if a less viscous fluid displaces a more viscous one [1]. Fingering can also result from a change in permeability in a porous medium as in reactive dissolution instabilities [2][3][4][5][6][7][8][9][10]. In these cases, the invading fluid contains chemicals which dissolve the solid matrix of the porous medium, leading to a related increase in porosity behind the reaction front.…”

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confidence: 99%

“…The experiments and nonlinear simulations of a RDC model give results in good agreement. We emphasize that the modeling of this precipitation-induced fingering is analogous to that of reactive viscous fingering [20,21,[24][25][26][27] and dissolution-driven fingering [2][3][4][5][6][7][8][9][10] with nonmonotonic profiles. The present study paves the way to future detailed analysis of the influence of precipitation reactions on the stability of displacement processes in porous media.…”

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Hydrodynamic Fingering Instability Induced by a Precipitation Reaction

et al. 2014

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We experimentally demonstrate that a precipitation reaction at the miscible interface between two reactive solutions can trigger a hydrodynamic instability due to the buildup of a locally adverse mobility gradient related to a decrease in permeability. The precipitate results from an A þ B → C type of reaction when a solution containing one of the reactants is injected into a solution of the other reactant in a porous medium or a Hele-Shaw cell. Fingerlike precipitation patterns are observed upon displacement, the properties of which depend on whether A displaces B or vice versa. A mathematical modeling of the underlying mobility profile confirms that the instability originates from a local decrease in mobility driven by the localized precipitation. Nonlinear simulations of the related reaction-diffusion-convection model reproduce the properties of the instability observed experimentally. In particular, the simulations suggest that differences in diffusivity between A and B may contribute to the asymmetric characteristics of the fingering precipitation patterns. DOI: 10.1103/PhysRevLett.113.024502 PACS numbers: 47.55.P−, 47.15.gp, 47.56.+r, 47.70.Fw Chemical reactions are able to influence and even more strikingly induce hydrodynamic fingering instabilities of a frontal interface when a high mobility fluid displaces a less mobile one in a porous medium. This occurs in viscous fingering if a less viscous fluid displaces a more viscous one [1]. Fingering can also result from a change in permeability in a porous medium as in reactive dissolution instabilities [2][3][4][5][6][7][8][9][10]. In these cases, the invading fluid contains chemicals which dissolve the solid matrix of the porous medium, leading to a related increase in porosity behind the reaction front. As a result, the resistance to flow decreases in these higher mobility reactive zones, which favors further dissolution, giving, thus, a positive feedback leading to instability. Dispersion of reactants is the stabilizing factor counteracting the growth of fluid channels in order to provide a fingered pattern with a given characteristic wavelength [2,5,7,10]. The reverse case of precipitation is not expected to destabilize an interface as the related decrease in permeability and, hence, in mobility behind the front is expected to block the flow rather than destabilize it. There is, however, increased interest to understand the effect of precipitation reactions during flow displacements in porous media in the context of CO 2 sequestration techniques [11][12][13][14]. Mineralization by which CO 2 injected in a porous medium could undergo precipitation reactions (to yield carbonates, for instance [13][14][15][16]) is indeed promising in view of a permanent safe storage of CO 2 in geological strata. Understanding the conditions in which precipitations can affect the stability of the spreading CO 2 plumes [12] is, thus, particularly important.In this context, we demonstrate experimentally and explain theoretically how a precipitation reaction localized at th...

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Hydrodynamic Fingering Instability Induced by a Precipitation Reaction

et al. 2014

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“…The effects of convection and diffusion on dissolution patterns and heterogeneities on wormholing in the radial model were studied. Kalia and Balakotaiah (2009) studied the effect of heterogeneities of the porous medium on the dissolution patterns formed during a carbonate acidizing process using the two scale model. In their study, the porosity values were generated by adding a random number uniformly distributed in a range to the mean value of initial porosity.…”

Section: Network Model Approachmentioning

confidence: 99%

The Accuracy of Carbonate Matrix-Acidizing Models in Predicting Optimum Injection and Wormhole Propagation Rates

Akanni

Nasr‐El‐Din

2015

SPE Middle East Oil &Amp; Gas Show and Conference

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The efficiency of matrix stimulation in carbonates is based on the generation of wormholes that penetrate the formation beyond the damaged near-wellbore region. Face dissolution, conical wormholes, dominant wormholes, ramified wormholes, and uniform dissolution are different dissolution patterns that can be formed during a carbonate matrix acid treatment. However, the process is most successful when dominant wormhole patterns are formed.Studies have shown that there exists an optimum injection rate for the formation of dominant wormholes, and mathematical models have been developed to describe the propagation of wormholes and to obtain this rate for an efficient acid treatment. Most of these models give good predictions of the optimal flow rate or wormhole growth rate for laboratory experiments, but the challenge faced is in translating the results from laboratory to field scale. This paper classifies the existing carbonate acidizing models in literature into seven broad categories and discusses the theory behind the models, major assumptions made, practicality in field scale applications, and technical shortcomings. The limitations of these models, such as the incorrect scaling of linear core scale results to radial field scale applications, formation heterogeneity, and non-inclusion of additives in reaction rate calculations are highlighted and a proposal for improvement is made to enhance the accuracy of one of the models under field conditions. The recommendation has been made to inject the acidizing fluid at the maximum allowable injection pressure based on the fracture pressure limit due to the shortcomings in the available carbonate matrix-acidizing models in predicting the optimum injection rate at field conditions. To calculate the wormhole propagation rate for skin evolution monitoring in field treatments, the modified semi-empirical wormhole propagation model is recommended with the caveat of including the additives used in the field in the coreflood tests when obtaining the optimum rate parameters in the laboratory.

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“…To describe dissolution in porous media several models have been proposed so far including fractal models [16], capillary tube models [16][17][18], network models [19,20] and averaged models [21][22][23][24][25][26]. The averaged model due to relating between different scales have better forecasts of acidizing process [26].…”

Section: Introductionmentioning

confidence: 99%