April 6, 2011 l 1

Hydraulic Fracturing Fluid Considerations in 

Marcellus Shale Completions

EPA Hydraulic Fracturing Tech Workshop

Feb 24-25, 2011

Dennis Degner

Director of Completions 
April 6, 2011 l 2

Agenda

 Introduction

 Additives used in Marcellus Shale fracturing 

 Why we use these additives

 Testing performed

 Where do we go from here
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Introduction

 Hydraulic fracturing is key to shale development

– Fracturing creates a small conductive flow path for 

hydrocarbon to flow from low permeability reservoirs

– “Slickwater” style design most commonly used in 

Marcellus as well as other shale reservoirs

• Slickwater design consists of water, proppant (sand) 

and small amounts of additives for placement and 

water management 

 Additives used

– Friction Reducer

– Biocide

– Scale inhibitor

 Why do we use these additives in Marcellus fracturing?
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Friction Reducer

 A key to shale fracturing is pumping fluid at high rates

– High rate helps to transport proppant (usually sand)

– Creates a fracture network

 To reach required pump rates friction reducer is added 

reducing pressure at surface

 What is friction reducer?

– Polyacrylomide polymer

– Comes in dry powder and liquid form with mineral oil base

– Also used for soil stabilization and some children’s toys

 Friction reducer selection impacted by:

– Chemistry of source water for fracturing

– High salinity vs. fresh water = different products
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Friction Reducer - flow loop test data
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 Various water sources are used for Marcellus fracturing

– Ground water

– Surface water

– Produced water

 Pre-job water testing is conducted to assess preexisting bacteria present

 Test involves inoculating specific media in a serial 

dilution bottle with 1 ml of frac source water

 Change in bottle color directly relates to bacteria count

 Results guide additive concentrations used during 

fracturing

Biocide
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Biocide

 What are some impacts of untreated bacteria?

– Microbiological influenced corrosion

– Formation souring (creation of H2S in the formation)

– Microbial growth downhole restricting production

 How do we control bacteria?

– Add an organic biocide to sterilize the fluid

– Glutaralehyde/quaternary ammonium blend

– Added at low concentrations (± 0.5 gal/Mgal)

– Post fracturing testing conducted over life of a well

– Results used for biocide optimization

 Similar approach seen in medical equipment 

sterilization and hand sanitation
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Scale Inhibitor

 Due to minerals in the source water scale can form

 What are some ways scale can form?

– Pressure drop

– Temperature changes

– Mixing of different waters

– Agitation

 To prevent scale from forming a solvent based scale 

inhibitor is added to the fracturing water

 Added at low concentrations (± 0.1 gal/Mgal)

 Similar additives used in municipal water treatment, deicing agents and household cleaners
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Scale Inhibitor

 Common scale that could form in Marcellus Shale wells

– Barium Sulfate (BaSO4)

– Calcium Carbonate (CaCO3)

 Scale is difficult and expensive to remove

– Can require remedial large volume chemical treatment

– In certain cases mechanical removal is required

 Water testing can determine 

scale tendency

 Test results drive additive plan

 Produced water dissolves small 

amounts of minerals from the 

shale

– As a result scale inhibitor 

becomes more important
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Where do we go from here?

 Continue additive advancement with service provider 

and University partnerships with focus on salt water reuse (recycling)

 Develop fluid systems in line with 12 principles of 

Green Chemistry

 We share chemical best practices with:

– Industry

– State agencies

– Trade groups

 Keep volume used low

– < 1% of job volume

 Transparent operations
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Thank You

Questions?

EPA Hydraulic Fracturing Tech Workshop

Feb 24-25, 2011

Dennis Degner

Director of Completions