Modeling of the Sedimentation of NORM_Feb2014
-
Upload
donald-carpenter -
Category
Documents
-
view
216 -
download
0
Transcript of 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
© 2013 ARCADISApril 18, 20232
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
© 2013 ARCADISApril 18, 20233
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
© 2013 ARCADISApril 18, 20234
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
© 2013 ARCADISApril 18, 20235
Formation of Radiogenic Gamma Emitting Daughter Products Allow Radium-Enriched Barite to be Detected
© 2013 ARCADISApril 18, 20236
Numerous Surface Gamma Survey Approaches Facilitates Detection of Radium Contamination
Privileged & Confidential Prepared at the Request of Legal Counsel
Many sites can readily and cost effectively be assessed via general surface scanning
© 2013 ARCADISApril 18, 20237
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
© 2013 ARCADISApril 18, 20238
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
© 2013 ARCADISApril 18, 20239
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
© 2013 ARCADISApril 18, 202310
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
© 2013 ARCADISApril 18, 202311
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
© 2013 ARCADISApril 18, 202312
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
© 2013 ARCADISApril 18, 202313
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)
© 2013 ARCADISApril 18, 202314
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)
© 2013 ARCADISApril 18, 202315
Example PTM Application – Density Differences Reflected in Transport Patterns
Initial Placement Post-Flood Wave
QuartzBarite
© 2013 ARCADISApril 18, 202316
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
© 2013 ARCADISApril 18, 202317
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
© 2013 ARCADISApril 18, 202318
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
© 2013 ARCADISApril 18, 202319
• 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
© 2013 ARCADISApril 18, 202320
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
© 2013 ARCADISApril 18, 202322
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