Modeling of the Sedimentation of NORM_Feb2014

© 2012 ARCADISApril 18, 20231

Hydrodynamic Modeling of the Physical Dispersion of Radium - Enriched Barite Aids in Understanding NORM Distribution

J. Barry, Ph.D; D. Carpenter, CPG; M. Erickson, P.E

Society for Mining, Metallurgy and Exploration Annual Meeting

Salt Lake City, Utah

February 2014

Imagine the result


Geochemistry of barite formation

Incorporation of radium into barite

Stability of barite during particulate transport

Modeling of barite distribution

Assessment Framework for Aquatic Sites

Outline


Formation of Radium-Enriched NORM Scale and Precipitate is a Significant Problem

• Millions of barrels of petroleum-related NORM awaiting disposal

• 150,000 barrels being generated per year

• American Petroleum Institute in 1989 suggested that 1/3 of all producing U.S. oil and gas wells have elevated radiation


The Subsequent Redistribution of Radium-Enriched NORM can Result Significant Contamination

• Typical US-based oil and gas well generates 100 tons of NORM annually

• Average radioactivity of barite – 500 pCi/g

• Typical radioactivity action levels in range of 5 to 100 pCi/g

• Potentially result in formation of over 1,500 tons of impacted soil/sediment per year per well

• Potential for similarly significant NORM from mine and mill tailings effluent


Formation of Radiogenic Gamma Emitting Daughter Products Allow Radium-Enriched Barite to be Detected


Numerous Surface Gamma Survey Approaches Facilitates Detection of Radium Contamination

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Many sites can readily and cost effectively be assessed via general surface scanning


Surface Gamma Scanning Efforts maybe Complicated by the Presence of Surface Obstructions or Water• Standing water bodies or floodways

containing radium-enriched barite may not be amenable to comprehensive surface scanning

• Geomorphic stratified assessments provide safer, lower cost, and higher effectiveness in these situations

• Prioritization of assessment areas

• Allocation of resources

• Higher value of information


Nexus of Geomorphology, Hydrodynamics, and NORM Characterization in Drainage Basins

Geomorphology allows relative understanding of zones of greater sediment accretion and reworking

Hydrodynamics governs frequency and intensity of sediment transport and

reworking

Particle distributions, and thus NORM radioactivity

must be governed by physical processes

Investigation

Design


Precipitation of Alkaline Earth Sulfates can Co-Precipitate Radium Sulfate forming a NORM

Ba+2 + SO4-2 → BaSO4

Ba+2 + (Ra+2) + SO4-2 → Ba(Ra)SO4

Mineralogical Significance:

1) Barite density

2) Barite mineralogical stability


The Elevated Density of Barite is Particularly Significant During Particulate Transport

Quartz Calcite Barite0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

Comparative Mineral Densities in Grams per Cubic Centimeter

De

nsi

ty


The Insolubility of Barite Under Geochemically Oxidizing Conditions Prevents its Chemical Removal

Barium Solubility at Different pH Conditions – Oxidizing and 100 ppm Sulfate ion

Solution pH Equilibrium Barium Solubility (ppb)

4.0 23

7.0 23

The Hardness of Barite is Greater than Calcite Contributing to Preservation of its Large Fragment Size

Comparative Hardness of Barite

Mineral Moh’s Hardness Scale

Calcite 3

Barite 3 to 3.5


Transport of Barite Must Also Reflect the Large Fragment Dimensions of the Scale

Barite may be present as relatively coarse sand-size grains to potato chip-like flakes

Impacts its sedimentological behavior versus that of fine or very fine quartz or calcite sand/silt


Sediment Particle Transport Models can Readily Reflect the Distinctive Characteristics of Barite

Parameter Value

Particle Sediment Parameters Sediment Diameter (mm)

Sediment Density (kg/m3)

Bed Porosity

Diffusion Parameters

Particle-bed Interaction Coefficients

Bed grain size distribution

Density 2,650 kg/m3 (Quartz)

4,480 kg/m3 (Barite)

Fall Velocity 0.0011 m/sec (Quartz)

0.01 m/sec (Barite)

Critical Shear of Initiation 0.2235 N/m2 (Quartz)

3.0 N/m2 (Barite)

Critical Shear of Deposition 0.04 N/m2 (Quartz)

3.0 N/m2 (Barite)


Particle Tracking Model (PTM)

• PTM simulates sediment dispersion, fate, pathway, settling, deposition, mixing, and re-suspension processes

• The PTM parameters include:

- The hydrodynamic input (i.e. current velocities and water surface elevation from a hydrodynamic model)

- The sediment input (i.e. grain size, sediment densities, bed porosity, diffusion parameters and particle-bed interaction coefficients for each grain size fraction and each computational cell in the model domain)


Example PTM Application – Density Differences Reflected in Transport Patterns

Initial Placement Post-Flood Wave

QuartzBarite


PTM Sensitivity Analysis – Critical Shear• Critical shear of initiation is driven by grain density differences that have a large

impact on downstream particle movement for this flow event

0102030405060708090100

0.001

0.01

0.1

1

10

100

1000

10000

2000 3000 4000 5000

Perc

ent M

obili

ty

Trav

el D

ista

nce

(m)

Density (kg/m3)

Sensitivity Analysis to DensityBarite Density 4,480 kg/m3 , Quartz Density 2,650 kg/m3

Average Travel Distance

Maximum Travel Distance

Percent of Particles in Motion


Areas Favorable for Barite Accumulation can be Predicted

Outward Shoaling flow across point bar

Inner Bank

Region

Mid-Channel Region

Outer Bank

Region

Path Lines of secondary flow

Superelevated water surface

apex

bar tailbar

head riffle crest

inflectionpool

• It is possible to incorporate barite density and critical shear stress differences into the PTM and predict the optimal sites for barite sample collection

• Level of effort and data tradeoff vs. geomorphic interpretation


High/ Low Energy Depositional Sites and Barite Traps

Higher concentrations of heavy metals are found in high energy environment i.e. “bar head” compared to low energy “bar tail pools”

• Sediments are deposited wherever currents are slowed - Heavy metal minerals are deposited earlier than quartz

• Higher Energy Deposition Sites (Heavy Metal Minerals, Barite)- Gravel bar heads

- Riffles

• Lower energy deposition sites (quartz)

- On meanders along the inside of curve

- Bar tail pools


• Barite particles coarser than 50 µm will deposit preferentially in relatively high energy sites

• Very fine barite grains may be swept from high energy sites and preferentially deposited at lower energy sites

• Particles smaller than 50 µm collect at low energy, bar-tail, sites

Impact of Grain Size on Depositional Environment


Geomorphic Stratified Assessment for Submerged Framework

Site barite particle characteristics, release

mode and timing

Geomorphic strata Identification

Hydrology and flood history review

Hydrodynamic modeling and particle transport

evaluation

Conceptual Site Model / data

sufficiency review

Supplemental Field Assessment

Strata Prioritization & Initial Field Assessment


SiteExample


Summary

The Formation of Radium Barite Scale is a Significant Problem

The Subsequent Redistribution of Radium-Enriched NORM can Result in Significant Contamination

Numerous Surface Gamma Survey Approaches Facilitates Detection of Radium Contamination

Surface Gamma Scanning Efforts maybe Complicated by the Presence of Surface Obstructions or Water

Geomorphic Stratified Assessments Can Save Money, Time and Reduce Safety Risk when intrusive sampling is required


Imagine the result

Modeling of the Sedimentation of NORM_Feb2014

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