water quality, quantity, and management: lessons from the marcellus shale region
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civil and environmental engineering
Water Quality, Quantity, and Management: Lessons from the
Marcellus Shale Region
Radisav D. Vidic, PhD, PEDepartment of Civil and Environmental Engineering
University of Pittsburgh
civil and environmental engineering
Shale Gas Basins
civil and environmental engineering
Hydrofracturing
civil and environmental engineering
Water Supply Issues• Need 2 to 6 Million gallons of water per well for hydraulic
fracturing• Surface Water Withdrawals
– Concerns about depletion of water resources, especially in drought years– Impacts to aquatic life – Ability to get withdrawals approved– Don’t really need high quality water, but consistent quality is important
• Transportation of water– 1 MG = 200 trucks– Cost can be significant (up to $2/bbl)
• Water storage on site
civil and environmental engineering
Water Withdrawal in PA• Need 2 to 6 Million gallons of water per well for a multi-
stage hydrofracturingWater-use category Water withdrawal
(MGD)Percentage
(%)Public supply 1420 15Domestic 152 1.6Irrigation 24.3 0.3Livestock 61.8 0.6Aquaculture 524 5.5Industrial 770 8.1Mining 95.7 1Thermoelectric power plants 6430 67.7Marcellus Shale exploitation in 2013(Gaudlip et al. 2008)
18.7 0.2
civil and environmental engineering
Marcellus Shale Play is not a significant water user in PA
Water Use in PA
civil and environmental engineering
Water Transfer Issues
- Trucks- Temporary surface lines- Permanent subsurface lines
civil and environmental engineering
Water Storage Issues
Storage options:• Centralized
impoundment—now becoming more prominent
• Single pad-dedicated impoundment
• Frac tanks
Storage based on ultimate scale of operations (long vs. short term)
civil and environmental engineering
Volumetric Composition of Fracking Fluids
civil and environmental engineering
Fracture Fluid CompositionAdditive type Main Compound Purpose
Diluted acid (15%) Hydrochloric or Muriatic Dissolve minerals and initiates cracks in rock
Biocide Glutaraldehyde, DBNPA Bacterial control
Corrosion inhibitor N,n-dimethyl formamide
Prevents corrosion
Breaker Ammonium persulfate Delays breakdown of gel polymers
Crosslinker Borate salts Maintains fluid viscosity at high temperature
Friction reducers
Polyacrylamide Minimize friction between the fluid and the pipe
Mineral oil
Gel Guar gum or hydroxyethyl cellulose
Thickens water to suspend the sand
civil and environmental engineering
Fracture Fluid Composition
Additive type Main Compound Purpose
Iron control Citric acid Prevent precipitation of metal oxides
Oxygen scavenger Ammonium bisulfite Remove oxygen from fluid to reduce pipe corrosion
pH adjustment Potassium or sodium carbonate
Maintains effectiveness of other compounds (e.g., crosslinker)
Proppant Silica quartz sand Keeps fractures open
Scale inhibitor Ethylene glycol Reduce deposition on pipe
Surfactant Isopropanol Increase viscosity of fluid
civil and environmental engineering
Latest Fracture Fluid Designs
Water94.36%
Sand5.56% Additives
0.08%
Anti-micro-
bial37%
Scale inhibitor13%
Friction reducer
50%
Additives
civil and environmental engineering
Anatomy of a Vertical Well
Marcellus Shale wells are cased and grouted (using special cements) to prevent migration of natural gas and fluid from the producing zone up the well bore into fresh-water aquifers.
civil and environmental engineering
Wastewater Issues
Flowback water Produced water
Flowrate High Low (10-50 bbl/day)
Duration 1 – 2 weeks Life of the well
TDS < 200,000 mg/L > 300,000 mg/L
Composition Chemical additivesNaturally occuring constituents
Same as flowback but more salts
Water recovery
10 – 40 %
Flowrate varies with location
civil and environmental engineering
Wastewater Storage IssuesStorage options:• Centralized
impoundment• Single pad-
dedicated impoundment
• Frac tanks
Environmental Risks- Leakage- Erosion and sediment control
civil and environmental engineering
4(2)
3(1)
7(3) 29(15)
14(10)
29(15)
18(8)
2(1) 4(1)
2(2)
1(1) 26(4)
1(1)
15(3)
8(3)
23(5)
3(3)
Flowback Water Characterization
160 flowback water analyses (BOGM, MSC, etc.)
civil and environmental engineering
Flowback Water QualityConstituent Low Medium High
Ba (mg/L) 2,300 3,310 13,500
Sr (mg/L) 1,390 2,100 8,460
Ca (mg/L) 5,140 14,100 41,000
Mg (mg/L) 438 938 2,550
Hardness (mg /L as CaCO3)
17,900 49,400 90,337
TDS (mg/L) 69,400 175,600 345,000
Gross Beta (pCi/L) ND 43,415 597,000
Ra226 (pCi/L) ND 623 9,280
COD (mg/L) 850 12,550 36,600
civil and environmental engineering
Flowback Water Management
• Wastewater disposal- Injection/disposal wells- Disposal to dedicated treatment
facilities- Discharge to POTWs
civil and environmental engineering
Gas Drilling Wastewater Management
19
(Hart, P., 2011)
civil and environmental engineering
Disposal Wells
• Require demonstration that injected fluids remain confined and isolated from fresh water aquifers
• Limited capacities (1200 to 3000 bpd)• Substantial capital investment with uncertain life
span ($1M to $2M)• Probably will only play a limited role• Depleted shallower wells are currently being
evaluated!?!?
civil and environmental engineering
Microseismic Tests in Marcellus Shale
civil and environmental engineering
Dedicated Treatment Facilities
civil and environmental engineering
Impact on Surface Water Quality
civil and environmental engineering
(Casson, L., 2012)
Impact on Surface Water Quality
civil and environmental engineering
Disposal to POTWs• Chosen option in the past• POTWs use biological processes • Biological systems cannot handle high salinity
(few case studies above 35,000 mg/L)• Require an approved pretreatment program
civil and environmental engineering
Treatment for Reuse in Fracking Operations
• Reduce O&G industry needs for surface water• Reduce overall management costs
– Volume reduction– Transportation costs– Disposal costs
• Reduce potential liability
civil and environmental engineering
Water Bank Concept
• Reuse difficult for smaller operators– Insufficient well count– Insufficient capital
• Develop rules for water banking– Smaller operator dispose of their wastewater in
regional impoundments– Larger operators get credit for water reuse and
pollution elimination
civil and environmental engineering
Recycling/Reuse
- Works for 12-15 yrs
- Eventually we are a net producer of water
• 4800 wells on 625 mi2
• 3 refractures/well
• 33% water reuse
civil and environmental engineering
Total Water Balance Within a Gas Field
29
(Kujivenhoven et al., 2011)
civil and environmental engineering
Treatment Options
Total Dissolved Solids (mg/L)
Wat
er R
eco
very
(%
)
50
100
75
25,000 50,000 100,000 300,000
ReverseOsmosis
Limited recoveryat high TDS
Evaporation
Crystallizers
civil and environmental engineering
WATER SOURCE
FRAC OPERATIONS
WASTE BRINE
STORAGE
FLOWBACK
PRODUCED WATER
ROAD DEICING
SALT
PURGE TO DISPOSAL
BRINE CRYSTALLIZER
BRINE CONCENTRATORVolume
ReductionBased on
TDS
RECOVERED WATER
Pretreatment
95% Volume
Reduction
Complete Treatment Process
civil and environmental engineering
Gas Drilling Wastewater Management
32
(Hart, P., 2011)
civil and environmental engineering
Salt production in Marcellus region
• 100,000 wells• 10 barrels/day/well of produced water• 300,000 mg/L salinity of produced water• 80% salt recovery
• Total NaCl produced in PA = 8 million tons• Total salt use for deicing in the US = 12-15 million tons
civil and environmental engineering
AMD in Pennsylvania
• Pennsylvania’s single greatest source of water pollution– Contaminated 4,000 miles of streams
• Elevated levels of iron and sulfate• Can have elevated hardness• TDS typically around 1,000 mg/L
• May be suitable as fracking water make up with little or no treatment
civil and environmental engineering
Why AMD?
Permitted wells Abandoned discharge Reclaimed discharge
civil and environmental engineering36
Hydraulic fracturing
Abandoned mine drainage (AMD)
Abandoned mine drainage (AMD)
Flowback waterFlowback water
Co-treatment of flowback water and AMD
Barium, Strontium, Calcium Sulfate
Enables the reuse of flowback water for hydraulic fracturing with limited treatment => decreases the treatment and transport cost
of flowback water
civil and environmental engineering
Summary• Marcellus shale development hinges on documenting
environmental impacts and developing sustainable water management
• Almost no direct disposal options and limited treatment options for flowback/produced water
• Flowback water reuse appears to be the most effective option
• Water reuse has a finite lifetime• Salt management may become a major issue in PA • AMD is a promising/convenient water source for
hydraulic fracturing
civil and environmental engineering
Thank You for Your Attention
Questions?
civil and environmental engineering
Natural Gas Production
Source: Annual Energy Outlook, EIA, 2011
civil and environmental engineering
History of Hydrofracturing
• First test in 1903• First commercial use in 1949• More than 1,000,000 wells by 1998• Nowadays, 35,000 wells per year with new
technology
civil and environmental engineering
Well Pad
Madden 2H, Lycoming County
civil and environmental engineering
Multiwell Pads
civil and environmental engineering
Rapid Marcellus Development
civil and environmental engineering
Typical Efficiencies of Thermoelectric Power Plants
Source: Stilwell et al., 2009
civil and environmental engineering
Water Use in Thermoelectric Power Plants
civil and environmental engineering
Flow scheme 1: Conventional Water Management
Well 1
Class II WellDisposal
“Fresh”Water
Flowback
Represents Maximum Water Demand (No Water Reuse)
Conventional approach in Barnett and other plays Difficult in Marcellus (only 7 Class II wells)
civil and environmental engineering
Flow scheme 2: On-Site Primary Treatment for Reuse
Well 1
Well 2
Blend
Makeup Water(Fresh Water)
On-SiteSettling
SS & FR Rem
High TDSReuse Water
civil and environmental engineering
Flow scheme 3: Off-Site Primary Treatment for Reuse
Well 1
Rapid Mixw/ Caustic& Flocculant
Sedimenta-tion & Hard-ness Rem
Rapid SandFilter
Belt Press Disinfect(Ozone orPeroxide)
Solids to Landfill
On-SiteSettling SS Removal
Near-Field Primary Treatment
Well 2
Blend
Makeup Water(Fresh Water)
High TDS WaterFor Reuse
civil and environmental engineering
Flow scheme 4: Off-Site Primary Treatment and Demineralization
Well 1
On-SiteSettling SS Removal
Well 2
Blend
Makeup Water(Fresh Water)
Distilled WaterFor Reuse
Near FieldPrimaryTreatment
Demineral-Ization
MechanicalVapor Recomp Disposal
(Class II Well)OrBy-ProductRecovery (Crystallizer)
ConcentratedBrine
civil and environmental engineering
Flow Scheme FS 1 FS 2 FS 3 FS4
Method Transport to Class II Well for Disposal
“In Field” Primary Treatment for Reuse
“Near Field” Precipitation
for Reuse
“In-Field” Evaporation
for Reuse
Treatment $ - 71 83 119
Transport $ 75 1 24 24
Brine Disposal $ 60 - - 19
Sludge Disposal $ - 2 6 6
Total Cost ($x1000) 135 74 113 168
Cost per barrel 5.67 3.10 4.75 7.05
Hardness Removal 100% 0% 97% 100%
Ba removal 100% 0% 99% 100%
Salt Removal 100% 0% 0% 100%
Water reused 0 99% 97% 90%
Basis: 1 million gallons of flowback (23,800 barrels)
Economic Comparison of Flow Schemes
civil and environmental engineering
Geosteering
civil and environmental engineering
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