POSTER MICP Symposium Barrett Poster

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    Investigating Microbially Induced Calcite Precipitation for Fracture

    Permeability Reduction in RocksNicholas Bucci, Huijie Lu PhD, Ehsan Ghazanfari PhD.

    Civil and Environmental Engineering

    ABSTRACT APPARATUS RESULTS

    PROCEDURE

    Barrett Research Scholarships

    Microbially Induced Calcite Precipitation (MICP) is a bio-

    geochemical process that produces calcium carbonate precipitation

    within a pours media matrix such as soil, or bedrock. Preventing

    contaminant migration via fracture networks in bedrock is extremely

    important for preserving our precious groundwater resources. MICP

    offers an attractive alternative method for permeability reduction to

    traditional grouting/cementation technologies due to its low

    viscosity reagents and low-pressure application technique. The

    effectiveness of MICP for rock fracture sealing and permeability

    reduction is being comprehensively evaluated for the distribution

    patterns of CaCO3 precipitation, and the resistance of precipitates to

    long-term persistent changes in temperature, pressure, and

    groundwater flows in subsurface environments. This research is

    exploring and developing the necessary laboratory methodologies,

    apparatuses, and procedures required to generate accurate data in

    support of MICP use in situ.

    AKNOWLEDGEMENTS

    Effluent Stand

    Core Holder

    Core Holder

    Pipe Clamp

    Influent

    Steel Wire

    Effluent

    Collection

    Fractured Core

    Stand Clamp

    Viton Jacket

    Syringe Pump

    Pre-MICP Computed Tomography Scan:

    Skyscan 1173 High Energy Micro-CT

    Vacuum Chamber Saturation

    Pre-MICP Constant Head Hydraulic Conductivity Test

    ASTM D5084-10 =

    MICP treatment

    1 bacterial broth flush (Sporosarcina Pasteurii)

    2 reagent flushes ( 1M CO(NH2)2 + 1M CaCl2(2H2O) + 1000mL H2O)

    Post-MICP Computed Tomography Scan:

    Post-MICP Constant Head Hydraulic Conductivity Test

    CT Image Analysis

    Effluent Concentration Analysis

    Break down apparatus, visually observe the rock core.

    Lucas Howard, Robert Caulk, Max Graves, Andrea Pearce, Joan

    Rosebush, Sara Dorr, Austin Grant, Kira Kelley, Anna Waldron

    The test apparatus was loosely modeled after an Autolab 1500 tri-axial

    cell, and optimized for the needs of this research.

    Top and bottom core holders were fabricated from plastic rather than

    expensive and excessively durable titanium or aluminum.

    Fluid confining pressure was removed due to low pressure reagent flow

    High resolution cross sectional

    images were generated using a

    Skyscan 1173 High Energy

    Micro-CT scanner. A software

    uses data collected from

    penetrative X-rays with complex

    algorithms which allows these

    cross sections to be created.

    Small changes in fracture

    aperture are visible at this

    printed resolution, however the

    images must be digitally

    observed at full resolution and

    zoom in order to begin

    volumetrically quantifying the

    precipitation within the fracture.

    * This research is ongoing

    CONTAMINANT MIGRATION?

    Groundwater contaminants can originate from septic

    tanks, nuclear waste disposal, and anything in

    between. These contaminants easily migrate through

    shallow soils and into bedrock fracture networks

    until ending up in a groundwater resources that may

    end up being consumed by humans.

    A constant head Hydraulic

    Conductivity Test was

    performed in accordance to

    ASTM D5084-10 on the first

    sandstone rock core before

    and after MICP treatment in

    order to quantify the changes

    in permeability that occurred.

    The test involves flowing

    water through the rock core

    by means of head pressure

    and recording the effluent

    flow rate. Three trials were

    performed to ensure results

    were precise and to calculate a

    more accurate average value.

    K value:Pre MICP = (9.5452 +/- stdev)*m/sPost MICP = (1.5355 +/- stdev)*m/s

    Preliminary results suggest permeability reductions

    as high as 84% after being treated with MICP.