water quality, quantity, and management: lessons from the marcellus shale region

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


Shale Gas Basins


Hydrofracturing


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


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


Marcellus Shale Play is not a significant water user in PA

Water Use in PA


Water Transfer Issues

- Trucks- Temporary surface lines- Permanent subsurface lines


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)


Volumetric Composition of Fracking Fluids


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


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


Latest Fracture Fluid Designs

Water94.36%

Sand5.56% Additives

0.08%

Anti-micro-

bial37%

Scale inhibitor13%

Friction reducer

50%

Additives


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.


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


Wastewater Storage IssuesStorage options:• Centralized

impoundment• Single pad-

dedicated impoundment

• Frac tanks

Environmental Risks- Leakage- Erosion and sediment control


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.)


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


Flowback Water Management

• Wastewater disposal- Injection/disposal wells- Disposal to dedicated treatment

facilities- Discharge to POTWs


Gas Drilling Wastewater Management

19

(Hart, P., 2011)


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!?!?


Microseismic Tests in Marcellus Shale


Dedicated Treatment Facilities


Impact on Surface Water Quality


(Casson, L., 2012)

Impact on Surface Water Quality


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


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


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


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


Total Water Balance Within a Gas Field

29

(Kujivenhoven et al., 2011)


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


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


Gas Drilling Wastewater Management

32

(Hart, P., 2011)


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


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


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


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


Thank You for Your Attention

Questions?


Natural Gas Production

Source: Annual Energy Outlook, EIA, 2011


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


Well Pad

Madden 2H, Lycoming County


Multiwell Pads


Rapid Marcellus Development


Typical Efficiencies of Thermoelectric Power Plants

Source: Stilwell et al., 2009


Water Use in Thermoelectric Power Plants


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)


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


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


High TDS WaterFor Reuse


Flow scheme 4: Off-Site Primary Treatment and Demineralization

Well 1

On-SiteSettling SS Removal

Well 2

Blend


Distilled WaterFor Reuse

Near FieldPrimaryTreatment

Demineral-Ization

MechanicalVapor Recomp Disposal

(Class II Well)OrBy-ProductRecovery (Crystallizer)

ConcentratedBrine


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


Geosteering


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water quality, quantity, and management: lessons from the marcellus shale region

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