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Item Darcy-scale modeling of microbially induced carbonate mineral precipitation in sand columns(2012-07) Ebigbo, Anozie; Phillips, Adrienne J.; Gerlach, Robin; Helmig, Rainer; Cunningham, Alfred B.; Class, Holger; Spangler, Lee H.This investigation focuses on the use of microbially induced calcium carbonate precipitation (MICP) to set up subsurface hydraulic barriers to potentially increase storage security near wellbores of CO2 storage sites. A numerical model is developed, capable of accounting for carbonate precipitation due to ureolytic bacterial activity as well as the flow of two fluid phases in the subsurface. The model is compared to experiments involving saturated flow through sand-packed columns to understand and optimize the processes involved as well as to validate the numerical model. It is then used to predict the effect of dense-phase CO2 and CO2-saturated water on carbonate precipitates in a porous medium.Item Potential CO2 leakage reduction through biofilm-induced calcium carbonate precipitation(2013-01) Phillips, Adrienne J.; Lauchnor, Ellen G.; Eldring, Joseph; Esposito, R.; Mitchell, Andrew C.; Gerlach, Robin; Cunningham, Alfred B.; Spangler, Lee H.Mitigation strategies for sealing high permeability regions in cap rocks, such as fractures or improperly abandoned wells, are important considerations in the long term security of geologically stored carbon dioxide (CO2). Sealing technologies using low-viscosity fluids are advantageous in this context since they potentially reduce the necessary injection pressures and increase the radius of influence around injection wells. Using aqueous solutions and suspensions that can effectively promote microbially induced mineral precipitation is one such technology. Here we describe a strategy to homogenously distribute biofilm-induced calcium carbonate (CaCO3) precipitates in a 61 cm long sandfilled column and to seal a hydraulically fractured, 74 cm diameter Boyles Sandstone core. Sporosarcina pasteurii biofilms were established and an injection strategy developed to optimize CaCO3 precipitation induced via microbial urea hydrolysis. Over the duration of the experiments, permeability decreased between 2 and 4 orders of magnitude in sand column and fractured core experiments, respectively. Additionally, after fracture sealing, the sandstone core withstood three times higher well bore pressure than during the initial fracturing event, which occurred prior to biofilm-induced CaCO3 mineralization. These studies suggest biofilm-induced CaCO3 precipitation technologies may potentially seal and strengthen fractures to mitigate CO2 leakage potential.Item Microbial CaCO3 mineral formation and stability in an experimentally simulated high pressure saline aquifer with supercritical CO2(2013-07) Mitchell, Andrew C.; Phillips, Adrienne J.; Schultz, Logan N.; Parks, Stacy L.; Spangler, Lee H.; Cunningham, Alfred B.; Gerlach, RobinThe use of microbiologically induced mineralization to plug pore spaces is a novel biotechnology to mitigate the potential leakage of geologically sequestered carbon dioxide from preferential leakage pathways. The bacterial hydrolysis of urea (ureolysis) which can induce calcium carbonate precipitation, via a pH increase and the production of carbonate ions, was investigated under conditions that approximate subsurface storage environments, using a unique high pressure (∼7.5 MPa) moderate temperature (32 °C) flow reactor housing a synthetic porous media core. The synthetic core was inoculated with the ureolytic organism Sporosarcina pasteurii and pulse-flow of a urea inclusive saline growth medium was established through the core. The system was gradually pressurized to 7.5 MPa over the first 29 days. Concentrations of NH4+, a by-product of urea hydrolysis, increased in the flow reactor effluent over the first 20 days, and then stabilized at a maximum concentration consistent with the hydrolysis of all the available urea. pH increased over the first 6 days from 7 to 9.1, consistent with buffering by NH4+ ⇔ NH3 + H+. Ureolytic colony forming units were consistently detected in the reactor effluent, indicating a biofilm developed in the high pressure system and maintained viability at pressures up to 7.5 MPa. All available calcium was precipitated as calcite. Calcite precipitates were exposed to dry supercritical CO2 (scCO2), water-saturated scCO2, scCO2-saturated brine, and atmospheric pressure brine. Calcite precipitates were resilient to dry scCO2, but suffered some mass loss in water-saturated scCO2 (mass loss 17 ± 3.6% after 48 h, 36 ± 7.5% after 2 h). Observations in the presence of scCO2 saturated brine were ambiguous due to an artifact associated with the depressurization of the scCO2 saturated brine before sampling. The degassing of pressurized brine resulted in significant abrasion of calcite crystals and resulted in a mass loss of approximately 92 ± 50% after 48 h. However dissolution of calcite crystals in brine at atmospheric pressure, but at the pH of the scCO2 saturated brine, accounted for only approximately 7.8 ± 2.2% of the mass loss over the 48 h period. These data suggest that microbially induced mineralization, with the purpose of reducing the permeability of preferential leakage pathways during the operation of GCS, can occur under high pressure scCO2 injection conditions.Item Engineered applications of ureolytic biomineralization: A review(2013-07) Phillips, Adrienne J.; Gerlach, Robin; Lauchnor, Ellen G.; Mitchell, Andrew C.; Cunningham, Alfred B.; Spangler, Lee H.Microbially induced calcium carbonate (CaCO3) precipitation (MICP) is a widely explored and promising technology for use in various engineering applications. In this review, CaCO3 precipitation induced via urea hydrolysis (ureolysis) is examined for improving construction materials, cementing porous media, hydraulic control, and remediating environmental concerns. The control of MICP is explored through the manipulation of three factors: (1) the ureolytic activity (of microorganisms), (2) the reaction and transport rates of substrates, and (3) the saturation conditions of carbonate minerals. Many combinations of these factors have been researched to spatially and temporally control precipitation. This review discusses how optimization of MICP is attempted for different engineering applications in an effort to highlight the key research and development questions necessary to move MICP technologies toward commercial scale applications.Item Biofilm detection in a model well-bore environment using low-field magnetic resonance(2015-09) Kirkland, Catherine M.; Hiebert, Dwight Randall; Phillips, Adrienne J.; Grunewald, Elliot; Walsh, David O.; Seymour, Joseph D.; Codd, Sarah L.This research addresses the challenges of the lack of non-invasive methods and poor spatiotemporal resolution associated with monitoring biogeochemical activity central to bioremediation of subsurface contaminants. Remediation efforts often include growth of biofilm to contain or degrade chemical contaminants, such as nitrates, hydrocarbons, heavy metals, and some chlorinated solvents. Previous research indicates that nuclear magnetic resonance (NMR) is sensitive to the biogeochemical processes of biofilm accumulation. The current research focuses on developing methods to use low-cost NMR technology to support in situ monitoring of biofilm growth and geochemical remediation processes in the subsurface. Biofilm was grown in a lab-scale radial flow bioreactor designed to model the near wellbore subsurface environment. The Vista Clara Javelin NMR logging device, a slim down-the-borehole probe, collected NMR measurements over the course of eight days while biofilm was cultivated in the sand-packed reactor. Measured NMR mean log T2 relaxation times decreased from approximately 710 to 389 ms, indicating that the pore environment and bulk fluid properties were changing due to biofilm growth. Destructive sampling employing drop plate microbial population analysis and scanning electron and stereoscopic microscopy confirmed biofilm formation. Our findings demonstrate that the NMR logging tool can detect small to moderate changes in T2 distribution associated with environmentally relevant quantities of biofilm in quartz sand.Item Fracture Sealing with Microbially-Induced Calcium Carbonate Precipitation: A Field Study(2016-04) Phillips, Adrienne J.; Cunningham, Alfred B.; Gerlach, Robin; Hiebert, Dwight Randall; Hwang, Chiachi; Lomans, B. P.; Westrich, Joseph; Mantilla, C.; Kirksey, J.; Esposito, R.; Spangler, Lee H.A primary environmental risk from unconventional oil and gas development or carbon sequestration is subsurface fluid leakage in the near wellbore environment. A potential solution to remediate leakage pathways is to promote microbially induced calcium carbonate precipitation (MICP) to plug fractures and reduce permeability in porous materials. The advantage of microbially induced calcium carbonate precipitation (MICP) over cement-based sealants is that the solutions used to promote MICP are aqueous. MICP solutions have low viscosities compared to cement, facilitating fluid transport into the formation. In this study, MICP was promoted in a fractured sandstone layer within the Fayette Sandstone Formation 340.8 m below ground surface using conventional oil field subsurface fluid delivery technologies (packer and bailer). After 24 urea/calcium solution and 6 microbial (Sporosarcina pasteurii) suspension injections, the injectivity was decreased (flow rate decreased from 1.9 to 0.47 L/min) and a reduction in the in-well pressure falloff (>30% before and 7% after treatment) was observed. In addition, during refracturing an increase in the fracture extension pressure was measured as compared to before MICP treatment. This study suggests MICP is a promising tool for sealing subsurface fractures in the near wellbore environment.