civil and environmental engineering

Sustainable Water Management for 

Marcellus Shale Development

Radisav D. Vidic, Ph.D., PE

Department of Civil and Environmental Engineering

Swanson School of Engineering

University of Pittsburgh

Pittsburgh, PA 15261
civil and environmental engineering

Shale Gas Basins
civil and environmental engineering

Hydrofracturing
civil and environmental engineering

Permitted Gas Wells in PA

Permits through February 2010
civil and environmental engineering

Water Supply Issues

• Need 1 to 8 Million gallons of water per well for hydrofracturing

• Surface Water Withdrawals

– Concerns about depletion of water resources, especially in drought years

– Impacts to aquatic life

– Negative publicity 

– 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 ($0.1/bbl to $2/bbl)

• Water storage on site
civil and environmental engineering

Fracing Fluids
civil and environmental engineering

Fracture Fluid Composition

Additive type Main Compound Purpose

Diluted acid (15%) Hydrochloric or Muriatic Dissolve minerals and initiates 

cracks in rock

Biocide Glutaraldehyde 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 

Mineral oil and the pipe

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 form 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

Wastewater Issues

• Frac Flowback Water

– High flows for short duration

– 10 to 40% of frac fluid recovered

– Most recovered in first 1 to 2 weeks

– TDS quickly climbs to 30,000 mg/L up to 200,000 mg/L

– Contains numerous chemical additives and naturally occurring 

constituents

• Produced Water

– Lower flows (2 to 30 bpd per well)

– Potentially very high TDS (100,000 to 300,000 mg/L)

– Continues to flow for the life of the well
civil and environmental engineering

Flowback Quantity vs. Time
civil and environmental engineering

Flowback Quantity vs. Time
civil and environmental engineering

Flowback Water Quality vs. Time

0

20000

40000

60000

80000

100000

120000

140000

160000

180000

1/23 1/24 1/25 1/26 1/27 1/28 1/29 1/30 1/31 2/1 2/2 2/3 2/4 2/5 2/6 2/7 2/8 2/9 2/10 2/11 2/12 2/13 2/14 2/15 2/16

Chloride mg/l Calcium mg/l Sodium mg/l Total Dissolved Solids (TDS) mg/l
civil and environmental engineering

Flowback Water Quality

Constituent Low 

(mg/L)

Medium 

(mg/L)

High 

(mg/L)

Ba 2,300 3,310 4,700

Ca 5,140 14,100 31,300

Fe 11 52 134

Mg 438 938 1,630

Mn 2 5 7

Sr 1,390 2,100 6,830

Hardness (as 

CaCO3)

17,900 49,400 90,337

Radioactivity ND ND ND

TDS 69,400 175,600 248,000
civil and environmental engineering

Flowback Water Management

• Evaporation in pits/ponds

• Injection/disposal wells

• Discharge to POTWs

• Direct reuse for fracing

• Treatment for reuse or surface discharge
civil and environmental engineering

Evaporation

• Natural pond evaporation not practical

– Precipitation < Evaporation

– Poor evaporation at high salinity

– Crusting over
civil and environmental engineering

Disposal Wells

• Significant regulatory hurdles

– Impacts to water supply aquifers

– Potential for injected water to migrate to streams

• Limited capacities (1200 to 3000 bpd)

• Substantial capital investment with uncertain life 

span ($1M to $2M)

• Probably will only play a limited role

• No new injection wells have been permitted!
civil and environmental engineering

Disposal to POTWs

• POTWs use biological processes such as lagoons, 

trickling filters, or activated sludge

• Biological systems cannot handle high salinity

– few case studies above 35,000 mg/l

• If high TDS + flow is significant portion of POTW 

influent, this is not an option

• Regulatory limitations on 

acceptance
civil and environmental engineering

Direct Reuse for Fracing

• TDS is too high

• Chlorides, in particular

– Corrosion concerns

– Impacts on fracing

• Solids, hardness, and bacteria removal

• Safety, corrosion, SRB downhole concerns

• Recycling of chemical additives
civil and environmental engineering

Treatment Options

Technology Maximum Feed TDS

(mg/L)

Energy Use

(kWh/100 bbl)

Capacitive Deionization 5,000 20

Electrodialysis reversal (EDR) 7,000 60

Electrodialysis 40,000 -

Reverse osmosis 35,000 15-30

Evaporation 100,000 400

Membrane distillation 250,000 600-700

Crystallizer 300,000 1000-1300
civil and environmental engineering

Treatment for Reuse in 

Fracing 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

Current Project at the University 

of Pittsburgh

Implementation of a holistic solution for 

management of flowback water from hydraulic 

fracturing

– develop an approach that will allow the use of flowback water 

from one well as a hydrofracing fluid for subsequent wells

– appropriate treatment/separation technology, which utilizes 

AMD wastewater for removing toxic divalent cations from the 

flowback water 

– develop novel slicking agents, which will be stable in brine 

solutions
civil and environmental engineering

AMD in Pennsylavania

• Pennsylvania’s single greatest source of water pollution

– Contaminated 3,000 miles of streams

• Often has low pH (<5) and elevated 

levels of iron and sulfate

• Can have elevated hardness

• TDS typically around 1,000 mg/L

• May be suitable as frac water make up with little or no treatment
civil and environmental engineering

AMD in Pennsylvania
civil and environmental engineering

Effect of AMD Blending on 

Dissolved Barium
civil and environmental engineering

Summary

• Marcellus shale development hinges on 

sustainable water management

• Almost no disposal options for flowback water

• Very few treatment options for disposal

• Flowback water reuse appears to be the most 

effective option

• AMD is potentially a suitable makeup water 

source in many locations
civil and environmental engineering

Thank you for 

Your Attention

Questions?