Utilizing Ultraviolet Light to 

Minimize Biocide Usage During 

Stimulation Operations 

Joseph Sinnott 

Supervisor, Completions Engineering 
Seeking a Cleaner, Greener Kill 

Motivation for UV trial 

EQT’s bacteria baseline 

Overcoming initial concerns 

Implementation 

Results and limitations 

Path forward 

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Environmental & Economic Motivation 

172 planned horizontals in 2013

Increased use of recycled water 

• 98% of flowback water 

• 90% of drilling water 

• 60% of produced water 

Over 1 billion gallons of frac water in 2013 

500,000 gallons of biocide at standard loadings 

• 3% of stimulation costs 

• 12-15% of chemical volumes 

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SRB Present Serious Issues in 

Production and Water Quality 

SRB – Sulfate Reducing Bacteria 

• Sulfates reduced; sulfides produced 

Why to avoid bacteria 

• H2S 

• Microbiologically influenced corrosion 

• Downhole scaling (FeS) 

• Nasty flowback water 

 SRB

 “Effects of Sulfate Reducing Bacteria on the 

Corrosion of X-65 Pipeline Carbon Steel,” 

NACE Corrosion 2012 Conference 

Multi-Chem Marcellus Shale Biotechnology Presentation, Sept 2012 
Few Red Flags in Produced Water 

Two independent studies demonstrate efficacy 

• Up to 3 years of production 

• Under 2 ppm H2S 

• 2 or less SRB bottles turned 

Goal: Achieve comparable results via greener 

means 

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Baseline Biocide Treatment During Frac 

Tributyl tetradecyl phosphonium chloride 

• TTPC 

• Quarternary Amine 

• 0.5 gpt under standard conditions 

Effective at surface and downhole 

• Kill study confirmations 

• Reduced performance as chlorides increase 

On-the-fly blending of impaired water 

• 100 bpm 

• Up to 100% recycled water 

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Avoiding the Light 

What about our nasty water? 

Can we treat at 100 bpm? 

Real-time confirmation of effectiveness? 

Where is the long-term protection? 

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Transmittance: Will the Light Penetrate? 

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UV Treatment 

Operation 

Range 

Operating 

Range 

Exceeded 
Enhanced Clarity Through Testing 

Bacteria bottles run every 2-3 

stages 

• Tanks 

• Post-UV treatment 

• Post-blender 

Blender contamination 

Transmittance measured 

throughout stage 

Biocide added 

downstream as needed 

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Implementation and Results 

Initial trials in July 2012

Transmittance has limited usage to 53% 

650 stages and 190,000,000 gal treated 

• 70,000 less gal of biocide 

• 22% cost reduction 

Equivalent kill to standard biocide loadings 

• Moderate  slight SRB concentrations 

• 2 bottle reduction targeted 

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The Challenges of On-the-Fly Treatments 

Incubation lag times 

Continuous testing 

Mechanical limitations 

• Physical footprint 

• Diesel-based equipment 

Extremely variable water quality 

• Cannot “set it and forget it” 

• Approaching the ceiling of effectiveness 

Potential effects on treatment pressures 

• Biocide allows faster hydration of friction reducer 

• 100 to 200 psi treating pressure variations 

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Stage-to-Stage Transmittance Variations 

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0 

10 

20 

30 

40 

50 

60 

70 

80 

90 

100 

0 

0.2 

0.4 

0.6 

0.8 

1 

1.2 

1.4 

1 4 7 10 13 16 19 22 25 

% Transmission 

FR and Biocide concentration (gpt) 

Stage 

Greene County Marcellus Well - 48% Treated 

FR- calc conc Biocide-calc conc Transmission Average UV Cut-Off 
Reduced Biocide and Increased Treating 

Pressures Have Not Affected Fracs to Date 

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0 

0.2 

0.4 

0.6 

0.8 

1 

1.2 

1.4 

Biocide and FR Concentration (

3 8 14 20 25 30 35 41 47 65 83 88 

gpt) 

%Transmittance

Average of FR concentration Average of Biocide Concentration 
A Cleaner, Greener, and Part-Time Killer 

UV treatment + biocide is current EQT SOP 

Minimal pre-treatment (and cost) a top priority 

• Logistical benefits to minimal treatment 

• No short or long-term effects observed 

35% reduction in biocide a great first step 

• Technological advances to handle nastier water 

• Cost-effective pre-treatment options 

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