civil and environmental engineering 1 

Reuse%of%Produced%Water%for%

Hydraulic%Fracturing%

Radisav%D.%Vidic,%Ph.D.,%P.E.%

Department!of!Civil!and!Environmental!Engineering!

University!of!Pi7sburgh,!Pi7sburgh,!PA!15261!
civil and environmental engineering 

Produced Water Reuse Considerations 

• Quantity 

– Large: justify effort to reduce fresh water needs in drought-sensitive 

areas 

– Small: blend to reduce disposal challenges 

• Quality 

– Impact on water quality after mixing with makeup water 

• Legal issues 

- Many lease arrangements require purchase of groundwater from 

landowner 

- Groundwater wells are drilled by operators and water is sold to 

operators by landowner 

2 
civil and environmental engineering 

Early Produced Water (Flowback) 

3 

Formation Initial (10 days) Water 

Volume 

% Needed for Next Well 

Mississippi Lime, Permian 

basin 

> 30,000 bbl > 50% 

Barnett, Eagle Ford, 

Niobrara, Utica, (Marcellus) 

8,000-30,000 bbl 10-40 % 

Haynesville, (Marcellus) 8,000 bbl < 10% 

Mantell, M. SPE Workshop, Ft. Worth, TX, March 2013. 
civil and environmental engineering 

Long-Term Produced Water 

4 

Formation Produced Water 

Volume 

(bbl/MMCF) 

Remarks 

Mississippi Lime, 

Permian basin 

> 200 Very high produced water generating 

play 

Barnett 70-200 High volumes of natural formation 

water present in/near target 

Niobrara, Eagle Ford 25-70 Relatively desiccated formation 

Marcellus, Utica, 

Haynesville 

< 25 Highly desiccated formation, capillary 

pressure binds water (imbibition) 

Mantell, M. SPE Workshop, Ft. Worth, TX, March 2013. 
civil and environmental engineering 

Produced Water Quality Considerations 

• Defining the optimal fresh to flowback water ratio to 

identify the maximum percentage of flowback that can 

be used in the frac fluid 

• Determining the optimal chemical composition of frac

fluid using flowback water to ensure an effective frac

without over spending on treatment 

• Identifying the maximum TDS, bacteria, barium, chloride 

and pH levels that can be present without causing 

scaling, corrosion or friction 

• Evaluating the optimal water chemistry for polymer 

based frac gels to achieve a fluid that can carry optimal 

volumes of proppant whilst still being cost effective 

5 
civil and environmental engineering 

Frac Fluid Design 

6 

Parameter Limit Consideration 

pH 6.0 – 8.0 Fluid stability, Scaling 

Chlorides < 20,000 mg/L Fluid stability 

Iron < 20 mg/L Fluid stability 

Ca, Mg, Ba, SO4, CO3 f(P, T, pH) (~350 mg/L) Scaling 

Bacteria Count < 100/100 mL Bacterial growth 

Suspended Solids < 50 mg/L Well plugging 

Oil and Soluble Organics < 25 mg/L Fluid stability 

Hydraulic Fracturing Expert Panel, 9/26/07 
civil and environmental engineering 

Water Quality Considerations 

• Fresh water was the dominant source for many years 

• These limits represent the least common denominator 

(everyone was comfortable) 

• No tests with actual fluids to establish true chemical limits 

• Product manuals were often an exercise of “copy and paste” 

7 

Water quality established when: 

• One rig, one well, one frac (one 

lateral, few stages) 

• Fresh water widely available 

• Ample disposal capacity 

• Reuse of produced water not 

even on the radar screen 

Present situation: 

• One rig, multiple wells 

• Each lateral with many (10-25) 

stages 

• Fresh water under scrutiny 

• Reuse of produced water is a 

necessity in some plays 
civil and environmental engineering 

Water Quality Considerations 

• Who makes the decision? 

- In-house engineer, completions engineer, sales engineer 

• Water quality requirements should be developed based on 

actual water chemistry 

• Economics drives the choices 

- Focus on minimal water treatment to promote reuse 

• Key driver for water quality requirements is the frac fluid 

performance 

8 
civil and environmental engineering 

Hydraulic Fracturing Systems 

9 

Slickwater

Linear Gel 

Cross-linked Gel 
civil and environmental engineering 10 

Slickwater System 

0.00

10.00

20.00

30.00

40.00

50.00

60.00

70.00

0 10 20 30 40 50 60 70

psi/ft

Rate (L/min)

Pressure in a 0.5" Pipe vs. Rate

Pure Water

Goal with FR

Friction reduction is 

the key issue with 

pure slickwater

fracturing 
civil and environmental engineering 

0 

10 

20 

30 

40 

50 

60 

70 

80 

0 20 40 60 80 100 120 140 160 180 

% DR 

Time (sec) 

11 

Friction Reduction Testing (FR Loop) 

%DR =

!Pwater - !Pfrac fluid

!Pwater

"100

Decrease due to shear 

degradation in the pump 

Delay due to 

FR hydration 
civil and environmental engineering 12 

Friction Reducer Performance Criteria 

based on Friction Loop Performance 

Kidder, M. SPE Workshop, Ft. Worth, TX, March 2013. 

Hydration Time to Sustained Drag Reduction 

(seconds) 

Sustained %DR 

for 3 min < 30 <45 <60 <90 

> 70 Best Good Maybe Poor 

> 60 Good Maybe Poor Not Acceptable 

> 50 Maybe Poor Not Acceptable Not Acceptable 

> 40 Poor Not Acceptable Not Acceptable Not Acceptable 

> 30 Not Acceptable Not Acceptable Not Acceptable Not Acceptable 
civil and environmental engineering 13 

FR at 0.033% in synthetic Marcellus 

produced water

Ferguson, M.L. and Johnson, M.A., JPT, 

November 2009 

Testing of Friction Reducer for Compatibility 

with Water Quality 

FR at 0.05% in actual Marcellus produced 

water
civil and environmental engineering 

FR at 0.5 gal/1,000 gal Fresh Water System Moderate Brine 

System 

Heavy Brine System 

TDS (mg/L) < 10,000 < 20,000 ~ 100,000 

(limit not yet defined) 

Total Multivalent 

Cations (mg/L) 

< 1,000 < 5,000 ~ 15,000 

(limit not yet defined) 

pH > 5 

Temperature 1-2 min to hydrate when T < 50F 30-45 s when T < 50F 

(increase FR conc. to 

improve hydration time) 

14 

Kidder, M. SPE Workshop, Ft. Worth, TX, March 2013. 

Friction Reducer Compatibility Criteria 
civil and environmental engineering 

Chemical%Criteria%for%Frac%Water%Makeup%

Chemical Parameter Maximum Value, mg/L 

TDS 50,000 

Hardness 26,000 

HCO3 300 

SO4 50 

Cl 45,000 

Na 36,000 

Ca 8,000 

Mg 1,200 

K 1,000 

Fe 10 

Ba 10 

Sr 10 

Mn 10 

15 

Industry Contact Group 

Final Report, WVU (DOE Award #: DE-FE0001466), June 2012 

Another consensus 

poll 
civil and environmental engineering 

Chemical%Criteria%for%Frac%Water%Makeup%

Chemical Parameter Maximum Value, mg/L 

TDS 50,000 

Hardness 26,000 

HCO3 300 

SO4 50 

Cl 45,000 

Na 36,000 

Ca 8,000 

Mg 1,200 

K 1,000 

Fe 10 

Ba 10 

Sr 10 

Mn 10 

16 

Industry Contact Group 

Final Report, WVU (DOE Award #: DE-FE0001466), June 2012 
civil and environmental engineering 17 

Sulfate%Concern%due%to%Downhole%PrecipitaDon%

Scaling on production 

Casing (+NORM?) 

“Homogeneous “ scaling Formation of plugs 

Biological activity 

(SRB)?? 
civil and environmental engineering 18 

Sulfate%PrecipitaDon%Downhole

SO4%(mg/L)% BaSO4%volume%

(m3)%

Volume%

percentage%

compared%with%

proppant

200! 0.98! 0.1%!

800! 4.9! 0.5%!

2000! 9.8! 1.3%!

Calculations performed using: 

- Fracturing fluid volume = 3 million gal 

- 9%w proppant

- Proppant density = 1201 kg/m3 

Negligible volume compared with the volume of proppant

injected 
civil and environmental engineering 19 

Linear Gel System 

• Guar gum or its derivatives

– Hydroxy-propyl-guar (HPG) 

– Carboxy-methyl-hydroxy-propyl-guar (CMHPG) 

• Cellulose derivatives 

– Hydroxy-ethyl-cellulose (HEC) 

• Require moderate pH (6-8) to ensure proper hydration 

• Guar is insensitive to: 

– High TDS 

– Multivalent (hardness) ions 

• Crosslinkers (aluminum, boron, titanium, zirconium) should be 

minimized to reduce the risk of accidental cross-linking in the event of 

unexpected pH increase 
civil and environmental engineering 

Guar – Borate System 

• Generally adaptable to a variety of water conditions 

• Desirable characteristics for proppant placement (early 

viscosity, shear recovery) 

• Requires high pH (8.5 to >12) 

- Low temperature (8.5 to 10.0) 

- High temperatures require higher pH (10.0 to >12) 

• Limited performance above 300°F 

20 

Cross-linked Gel System 
civil and environmental engineering 

Metallic crosslink system 

• More potential issues with challenging waters 

• Flexible pH (4 to 11) 

• Must be properly delayed (shear degrading) 

• Balancing delay and early crosslinking/viscosity is 

difficult 

• Existing crosslinked packages developed for fresh 

water 

• Adapting fluids to more challenging conditions 

21 

Cross-linked Gel System 
civil and environmental engineering 22 

Ideal Viscosity Response

(High Performance Fluid)

0

200

400

600

800

1000

0:00 0:30 1:00 1:30 2:00

Time (HH:MM)

Apparent Viscosity (cp) and Shear 

Rate (1/s)

50

100

150

200

250

300

Temperature (degF)

Shear Rate

Apparent Viscosity

Fluid Temperature

High Shear 

Period

Early Time 

Viscosity 

(Wellbore)

Thermal 

Stability for 

Pump Time

Ideal Viscosity Response

(High Performance Fluid)

0

200

400

600

800

1000

0:00 0:30 1:00 1:30 2:00

Time (HH:MM)

Apparent Viscosity (cp) and Shear 

Rate (1/s)

50

100

150

200

250

300

Temperature (degF)

Shear Rate

Apparent Viscosity

Fluid Temperature

High Shear 

Period

Early Time 

Viscosity 

(Wellbore)

Thermal 

Stability for 

Pump Time

Performance Testing 

Bjornen, K. et al. SPE Workshop, Ft. Worth, TX, March 2013. 
civil and environmental engineering 23 

Property Acceptable Range Affected 

TDS < 30,000 mg/L FR / Hydration 

Total Hardness 

(Ca + Mg + Ba + Sr) 

< 10,000 mg/L FR / Hydration 

Sulfates < 200 mg/L Scaling tendency 

pH 6-8 Hydration 

Carbonates < 200 mg/L Scaling tendency 

Bicarbonates < 400 mg/L Scaling tendency 

Reducing agents 0 ppm Hydration / Breaker 

Silica < 1 mg/L Crosslinking 

Iron < 10 mg/L Crosslinking / Hydration 

Phosphates < 5 mg/L Crosslinking 

Bacteria < 105/mL Gel / Crosslinking 

Water Quality Requirements 

Chesapeake Energy Corporation
civil and environmental engineering 24 

High%Alkalinity%Water%Challenging%for%GuarOBorate%%

0.00

0.20

0.40

0.60

0.80

1.00

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0 12.0 13.0 14.0

pH

! i

H3BO3

H2BO3

-

HBO3

-2

BO3-3

0.00

0.20

0.40

0.60

0.80

1.00

0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0

pH

αi

H2CO3

HCO3-

CO3

-2

High pH is necessary for borates 

to crosslink guar gel 

High pH accelerates scaling 

Bjornen, K. et al. SPE Workshop, Ft. Worth, TX, March 2013. 
civil and environmental engineering 

• High pH to achieve borate cross-linking drives CaCO3, and Mg(OH)2

scale formation 

– No blending 

• 3,000 – 7,000 lb solids 

– 90/10 produced water/fresh water blend 

• 4,900 - 9800 lb solids 

• 250,000 lb of proppant used per stage 

– 10% fines translates into 25,000 lb

• Impact of calcite solids and other scaling solids on proppant conductivity 

not well understood 

– Do the these solids flow back due to small micron size? 

– Do they stay downhole? 

25 

Impact%of%Precipitates%–%Eagle%Ford%

Calcite solids 

Bjornen, K. et al. SPE Workshop, Ft. Worth, TX, March 2013. 
civil and environmental engineering 26 

Parameter Typical Standard Elevated Success 

Iron < 10 ppm Up to 200 ppm

Magnesium < 50 ppm Up to 150 ppm

Calcium < 200 ppm Up to 2,000 ppm

Bicarbonate < 500 ppm No upper limit 

Chlorides < 10,000 ppm No upper limit 

Oil < 10 ppm or no oil 

Oil does not interfere BUT 

other contaminants inside of 

the oil may 

Kidder, M. SPE Workshop, Ft. Worth, TX, March 2013. 

Water%Quality%Criteria%%

- Frac fluid compatibility testing should be done if water quality is 

approaching the prescribed limits 

- Impact of salt on scaling propensity in the proppant pack or production 

lines
civil and environmental engineering 27 

Hybrid Systems 

- Lead off with a simple slickwater fluid with 100 

mesh proppant

- Switch to a linear guar gel and larger proppant

- Finish with a higher proppant loading and Xlinked gel 

Need to satisfy ALL water quality criteria 
civil and environmental engineering 28 

• Dissolved ions (chlorides and TDS) 

– Generally not looking to remove; blending with fresh water is the 

control strategy 

• Other dissolved constituents 

• Suspended solids (turbidity and TSS) 

– Can decrease biocide effectiveness 

– Remove by filtration 

Treatment/Management Selection 

Constituent Above Ground In-well 

Hardness Softening Complexation

Barium Sulfate precipitation Complexation

Iron Aeration Complexation
civil and environmental engineering 

• Produced water reuse depends on both quantity and quality 

• Old water quality criteria need to be revised based on specific 

applications and compatibility tests 

• New chemical formulations extend water reuse 

• Water compatibility with frac fluid design governs treatment 

requirements 

– Slickwater: easy to reuse water by choosing the right friction 

reducer; scaling concerns may be important 

– Linear Gels: as long as pH does not increase above 8, similar 

criteria as for slickwater 

– Cross-linked Gels: Multivalent cations and crosslinker

concentration in the produced water are important criteria; scaling 

concerns may be important 

29 

Summary 
civil and environmental engineering 

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