printed by

www.postersession.com

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 𝐾 =∆𝑄∗𝐿

𝐴∗∆ℎ∗∆𝑡

• 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)*𝟏𝟎−𝟖m/s

Post MICP = (1.5355 +/- stdev)*𝟏𝟎−𝟖m/s

• Preliminary results suggest permeability reductions

as high as 84% after being treated with MICP.