## EPA Hydraulic Fracturing Workshop 1 February 24-25, 20112 

## High Rate Hydraulic Fracturing Additives in Non- Marcellus Unconventional Shales

Rick McCurdy Sr. Engineering Advisor Chemicals and Water Reclamation3 

## Agenda Non-Marcellus Unconventional Shales Typical Additives by Play 

### Recent Trends in Additive Selection Key Points4 

## Unconventional Shale Plays5 

## Shale Information

Shale Play Fayetteville Barnett Eagle Ford Haynesville Average Depth From Surface (ft) 4,500 7,400 9,000 11,500 Bottom Hole Temperature (F) 130 190 260 320 Bottom Hole Pressure (psi) 2,000 2,900 6,200 10,0006 

## Agenda Non-Marcellus Unconventional Shales Typical Additives by Play Purpose, Chemistry and Concentration 

### Recent Trends in Additive Selection Key Points7 

## Historical Additives by Play (non- MS) Additive Barnett Fayetteville Haynesville Eagle Ford Friction Reducer X X X X Biocide X X X X KCl Substitute X X X X Scale Inhibitor X X X Surfactant X X X X Hydrochloric Acid * X X X X Gel X X X Cross- linker X X Breaker X X X * - includes acid corrosion inhibitor and iron control8 

## Friction Reducer Purpose Reduces surface tension between fluid and pipe surface and helps to maintain laminar flow. 

### Chemistry Polyacrylamides Typically dispersed in a hydrocarbon carrier Anionic (most common) and cationic (less common) 

### Use Concentration 500 – 1,000 ppm 0.05 – 0.1% of total fluid pumped (v/v)10 

## Biocide Chemistry Glutaraldehyde Glut / quaternary amine blends THPS (tetrakis hydroxymethyl phosphonium sulfate) DBNPA (2,2 -dibromo, 3- nitriloproprionamide) Sodium hypochlorite ( NaClO ) All products are regulated under FIFRA and must be registered with the EPA and the States 

## Use Concentration 75 – 500 ppm 0.075 – 0.05% of total fluid11 

## Scale Inhibitor Purpose Prevents mineral scale formation as the stimulation fluid mixes with formation water or after dissolving existing mineral salts in the reservoir. Chemistry Polymers (most common)

― carboxylic acid

― acrylic acid Phosphonates (less common, many incompatible w/ other additives) Use Concentration 75 - 120 ppm 0.075% – 0.12% of total fluid pumped12 

## Potassium Chloride (KCl) Substitute Purpose Prevents the swelling of water sensitive clays Type and amount of clays can vary from shale to shale Drill cuttings and core analysis used to quantify Capillary suction time (CST) testing used to determine sensitivity to low salinity water13 

## Potassium Chloride (KCl) Substitute Chemistry Historically, quaternary amines

― Tetramethylammonium chloride (TMAC) Last year, move to choline chloride

― Commonly found in animal feed

― Also as a nutritional supplement for humans 

## Use Concentration 500 – 2,000 ppm O.05% - 0.2% of total fluid pumped TMAC

Choline Chloride14 

## Surfactant Purpose Reduce interfacial tension in the formation and promote more robust water recovery after hydraulic fracturing Prevent emulsions in shale plays containing significant amounts of oil, water and gas15 

## Surfactant Chemistry Variety of formulations

―Typically anionic, non - ionic or amphoteric

―Simple laurel sulfates to more complex fluoroand nano-surfactants 

## Use Concentration 500 – 1,000 ppm 0.05% - 0.1% of total fluid pumped16 

## Hydrochloric (HCl) Acid Purpose Dissolves contaminates in casing. Dissolves acid soluble minerals that may be present in the shale 

### Chemistry Typically 15% active Rapidly reacts with iron and minerals that may be present in the shale CaCO 3 

### + 2HCl CaCl 2 

### + H 2 

### O + CO 217 

## Hydrochloric (HCl) Acid Use Concentration Dependent on:

― Perf clusters / well

― Mineral composition of shale 

### Typical volumes

― 0.08% - 2.1% of total fluid pumped (as acid volume)

― 0.012% - 0.31% of total fluid pumped ( as active acid )18 

## Acid Corrosion Inhibitor Purpose Reduces corrosive attack on bare steel 

## Chemistry Complex Assortment

― Formic acid

― Amines, amides, amido-amines 

## Use Concentration Dependent on bottom hole temperature and exposure time 2,000 – 5,000 ppm of acid volume 0.0004% - 0.0043% of total fluid pumped19 

## Iron Control Purpose Prevents precipitation of any dissolved iron as acid reacts and spends 

### Chemistry Citric acid Acetic acid Thioglycolic acid EDTA 

### Use Concentration 5,000 ppm of acid volume 0.0004% – 0.011% of total fluid pumped20 

## Agenda Non-Marcellus Unconventional Shales Typical Additives by Play 

### Recent Trends in Additive Selection Key Points21 

## Green FracTM Initiated in 2009 Primary Drivers: Minimize Risk of Exposure To Workers During 

### Hydraulic Fracturing Activities Minimize Environmental Impact of Surface Spills 

### Evaluate – Eliminate - Replace22 

## Green Frac Status Additive Barnett Fayetteville Haynesville Marcellus Eagle Ford Friction Reducer GF* Test GF Test GF Test GF Test GF Test Biocide GF Test GF Test GF Test GF Test GF Test KCl Substitute Eliminated GF Substitute GF Substitute Eliminated GF Substitute Scale Inhibitor GF Test GF Test X X Surfactant Eliminated Eliminated Eliminated GF Test X Gel X X Occasional X Cross- linker X X Breaker X X Occasional X HCl X X X X X * - Green FracTM23 

## Agenda Non-Marcellus Unconventional Shales Typical Additives by Play 

### Recent Trends in Additive Selection Key Points24 

## Key Points Hydraulic fracturing fluids do not contain 596 toxic compounds. Chemical additives account for <1% of the total fluid pumped during the majority of hydraulic fracturing activities. Chesapeake’s Green FracTM program has eliminated or found more environmentally friendly alternatives for 3⁄4 of the additives historically used in hydraulic fracturing.

## High Rate Hydraulic Fracturing Additives in Non- Marcellus Unconventional Shales

Rick McCurdy Sr. Engineering Advisor Chemicals and Water Reclamation