Large‐Scale Experiments in Microbially Induced Calcite Precipitation (MICP): Reactive Transport Model Development and Prediction

Abstract

Design of in situ microbially induced calcite precipitation (MICP) strategies relies on a predictive capability. To date much of the mathematical modeling of MICP has focused on small‐scale experiments and/or one‐dimensional flow in porous media, and successful parameterizations of models in these settings may not pertain to larger scales or to nonuniform, transient flows. Our objective in this article is to report on modeling to test our ability to predict behavior of MICP under controlled conditions in a meter‐scale tank experiment with transient nonuniform transport in a natural soil, using independently determined parameters. Flow in the tank was controlled by three wells, via a complex cycle of injection/withdrawals followed by no‐flow intervals. Different injection solution recipes were used in sequence for transport characterization, biostimulation, cementation, and groundwater rinse phases of the 17 day experiment. Reaction kinetics were calibrated using separate column experiments designed with a similar sequence of phases. This allowed for a parsimonious modeling approach with zero fitting parameters for the tank experiment. These experiments and data were simulated using PHT3‐D, involving transient nonuniform flow, alternating low and high Damköhler reactive transport, and combined equilibrium and kinetically controlled biogeochemical reactions. The assumption that microbes mediating the reaction were exclusively sessile, and with constant activity, in conjunction with the foregoing treatment of the reaction network, provided for efficient and accurate modeling of the entire process leading to nonuniform calcite precipitation. This analysis suggests that under the biostimulation conditions applied here the assumption of steady state sessile biocatalyst suffices to describe the microbially mediated calcite precipitation.

Biogeochemical Changes During Bio-cementation Mediated by Stimulated and Augmented Ureolytic Microorganisms

“…In both specimens, C/C o values consistently increased more rapidly with injected volume along W1 to W2. Breakthrough curves from W2 to W3 were consistent with measured soil porosities and expected trends from numerical models 39 , suggesting that the W1 to W2 alignment may have been initially partially-saturated. Despite these differences, similar breakthrough curves for each well alignment suggested that advective-dispersive solution transport between tanks was comparable prior to treatments.

Figure 2Normalized bromide concentrations (C/Co) versus injected pore volumes (PV) from passive tracer testing completed from ( a ) Well 1 to Well 2 and ( b ) Well 2 to Well 3.

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Field-scale modeling of microbially induced calcite precipitation

“…What we consider important for investigating the upscaling of MICP processes between the laboratory and the field scale is a close cooperation between experimentalists and modelers, as demonstrated in this study and others, e.g., by [51], and, very importantly, more well-controlled largerscale experiments such as those conducted by [56]. A second, equally important, issue is that information on the setup is drastically reduced compared to well-controlled laboratory work, thus complicating determination of correct initial and boundary conditions or other properties of the simulation setup such as the initial distribution of porosity and permeability.…”

“…Applications found in the literature include the interaction of microbes with the subsurface transport of contaminants, [e.g., 37,63,69,74], microbially enhanced oil recovery [e.g., 44,53,54,72], or biomineralization, of which especially the engineered application of MICP has received considerable attention. Most numerical models for MICP are, similarly to the model used in this study, formulated at the REV scale (or Darcy scale) [e.g., 2,17,46,51,[76][77][78], while [64] and [80][81][82] use pore-network and pore-scale models, respectively.…”

Sand and silty-sand soil stabilization using bacterial enzyme–induced calcite precipitation (BEICP)

“…Even then, just growing and preserving the involved microorganisms under fieldlevel conditions would have its own set of complications. After two decades of active MICP research, therefore, it is noteworthy that relatively few large, meter-scale projects have yet been attempted within either lab or field studies using sand and natural soil systems (Burbank et al 2011;Gomez et al 2015;De Jong et al 2009;Nassar et al 2018;van Paassen et al 2009van Paassen et al , 2010a van Paassen 2011; Phillips et al 2016;van der Star et al 2011).…”