EPA Hydraulic Fracturing Workshop 1

February 24-25, 2011
2

High Rate Hydraulic 

Fracturing Additives in 

Non-Marcellus 

Unconventional Shales

Rick McCurdy

Sr. Engineering Advisor

Chemicals and Water Reclamation
3

Agenda

Non-Marcellus Unconventional Shales

Typical Additives by Play

Recent Trends in Additive Selection

Key Points
4

Unconventional Shale Plays
5

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 10,000
6

Agenda

Non-Marcellus Unconventional Shales

Typical Additives by Play

Purpose, Chemistry and Concentration

Recent Trends in Additive Selection

Key Points 
7

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 control 
8

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 fluid
11

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 pumped
12

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 water
13

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 Chloride
14

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 gas
15

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 pumped
16

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

CaCO3 + 2HCl CaCl2 + H2O + CO2
17

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 pumped
19

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 pumped
20

Agenda

Non-Marcellus Unconventional Shales

Typical Additives by Play

Recent Trends in Additive Selection

Key Points
21

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 - Replace
22

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 FracTM
23

Agenda

Non-Marcellus Unconventional Shales

Typical Additives by Play

Recent Trends in Additive Selection

Key Points
24

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