Appendix F
Chemical Additives Used in the High‐Volume Hydraulic Fracturing Operations
- Excerpts from US House of Representatives (2011) report documenting HVHF chemicals.
- Hydraulic fracturing chemicals used for hydraulic fracturing of the Franchuk 44‐20 SWH well (L. Helms, personal communication).
US House of Representatives HVHF Report (2011)
The US House of Representatives produced a report in 2011 documenting the most widely used chemicals in hydraulic fracturing between 2005 and 2009. The most commonly used compound, as measured by the number of products containing the chemical, was methanol.
Methanol (CH3OH) is a hazardous air pollutant and a candidate for regulation under the Safe Drinking Water Act (SDWA). Methanol is also called by numerous scientific and common names, including methyl alcohol, carbinol, methyl hydroxide, methylol, monohydroxymethane, wood alcohol, colonial spirit, Columbian spirit, hydroxymethane, wood naphtha, alcool methylique, alcool metilico, metanolo, methylalkohol, metylowy alkohol, pyroxylic spirit, wood spirit, pyro alcohol, spirit of wood, Bieleski’s solution, and NSC 85232 (NIST 2016).
Methanol was a component in 342 hydraulic fracturing products. Some of the other most widely used chemicals include isopropyl alcohol, which was used in 274 products, and ethylene glycol, which was used in 119 products. Crystalline silica sand (silicon dioxide or SiO2) appeared in 207 products, generally related to proppants used to hold open fractures.
According to the government report, in the five‐year period between 2005 and 2009, the 14 oil and gas service companies participating in the chemical study focusing on hydraulic fracture stimulation used more than 2500 specific products containing 750 chemicals and other chemicals. Overall, these companies used 780 million gallons of hydraulic fracturing products, which does not include the water added at the well site during the five‐year period of the study.
The list of the seven most commonly used compounds, the list in alphabetical order of the most common hydraulic fracture stimulation chemicals, and chemicals of concern are shown below:
The seven chemical components appearing most often in hydraulic fracture stimulation products used between 2005 and 2009.
| Chemical component | Number of products containing chemical |
| Methanol (methyl alcohol) | 342 |
| Isopropanol (isopropyl alcohol, propan‐2‐ol) | 274 |
| Crystalline silica – quartz (SiO2) | 207 |
| Ethylene glycol monobutyl ether (2‐butoxyethanol) | 126 |
| Ethylene glycol (1,2‐ethanediol) | 119 |
| Hydrotreated light petroleum distillates | 89 |
| Sodium hydroxide (caustic soda) | 80 |
Chemical components listed in the table below are a summary of those chemicals contained in 20 or more products.
The most common hydraulic fracture stimulation product chemicals.
Source: From US HR (2011).
| Chemical component | Chemical Abstracts Service (CAS) Registry Number | No. of products containing chemical |
| 1,2,4‐Trimethylbenzene | 95‐63‐6 | 21 |
| 2,2‐Dibromo‐3‐nitrilopropionamide | 10222‐01‐2 | 27 |
| Acetic acid | 64‐19‐7 | 56 |
| Aluminum oxide (alpha alumina) | 1344‐28‐1 | 24 |
| Aluminum silicate (mullite) | 1302‐76‐7 | 38 |
| Ammonium chloride | 12125‐02‐9 | 29 |
| Ammonium persulfate (diammonium peroxydisulfate) | 7727‐54‐0 | 37 |
| Citric acid (2‐hydroxy‐1,2,3‐propanetricarboxylic acid) | 77‐92‐9 | 29 |
| Corundum (aluminum oxide) | 1302‐74‐5 | 48 |
| Crystalline silica – cristobalite (SiO2) | 14464‐46‐1 | 44 |
| Crystalline silica – quartz (SiO2) | 14808‐60‐7 | 207 |
| Diesel | 68476‐34‐6 | 43 |
| Ethanol (ethyl alcohol) | 64‐17‐5 | 36 |
| Ethoxylated nonylphenol | 9016‐45‐9 | 38 |
| Ethylbenzene | 100‐41‐4 | 28 |
| Ethylene glycol (1,2‐ethanediol) | 107‐21‐1 | 119 |
| Ethylene glycol monobutyl ether (2‐butoxyethanol) | 111‐76‐2 | 126 |
| Formic acid | 64‐18‐6 | 24 |
| Glutaraldehyde | 111‐30‐8 | 20 |
| Guar gum | 9000‐30‐0 | 41 |
| Heavy aromatic petroleum naphtha | 64742‐94‐5 | 45 |
| Hexamethylenetetramine | 100‐97‐0 | 37 |
| Hydrogen chloride (hydrochloric acid) | 7647‐01‐0 | 42 |
| Hydrotreated light petroleum distillates | 64742‐47‐8 | 89 |
| Isopropanol (isopropyl alcohol, propan‐2‐ol) | 67‐63‐0 | 274 |
| Methanol (methyl alcohol) | 67‐56‐1 | 342 |
| Mullite | 1302‐93‐8 | 55 |
| Naphthalene | 91‐20‐3 | 44 |
| Petroleum distillates | a | 26 |
| Phenol‐formaldehyde resin | 9003‐35‐4 | 32 |
| Polyethylene glycol | 25322‐68‐3 | 20 |
| Polysaccharide | a | 20 |
| Potassium chloride | 7447‐40‐7 | 29 |
| Potassium hydroxide | 1310‐58‐3 | 25 |
| Propargyl alcohol (2‐propyn‐1‐ol) | 107‐19‐7 | 46 |
| Silica (silicon dioxide) | 7631‐86‐9 | 47 |
| Sodium chloride | 7647‐14‐5 | 48 |
| Sodium hydroxide (caustic soda) | 1310‐73‐2 | 80 |
| Toluene | 108‐88‐3 | 29 |
| Triethanolamine (2,2,2‐nitrilotriethanol) | 102‐71‐6 | 21 |
| Xylene | 1330‐20‐7 | 44 |
a No CAS number available.
Of the chemicals or products listed above, 29 chemicals are known or are possible human carcinogens, regulated under the SDWA for their risks to human health, or are listed as hazardous air pollutants under the Clean Air Act (US HR 2011). These chemicals, which were contained in hundreds of different products, are listed below:
Chemical components of concern: carcinogens, SDWA‐regulated chemicals, and hazardous air pollutants.
Source: From US HR (2011).
| Chemical component | Chemical category | No. of products |
| Methanol (methyl alcohol) | HAP | 342 |
| Ethylene glycol (1,2‐ethanediol) | HAP | 119 |
| Diesela | CAR, SDWA, HAP | 51 |
| Naphthalene | CAR, HAP | 44 |
| Xylene | SDWA, HAP | 44 |
| Hydrogen chloride (hydrochloric acid) | HAP | 42 |
| Toluene | SDWA, HAP | 29 |
| Ethylbenzene | SDWA, HAP | 28 |
| Diethanolamine (2,2‐iminodiethanol) | HAP | 14 |
| Formaldehyde | CAR, HAP | 12 |
| Sulfuric acid | CAR | 9 |
| Thiourea | CAR | 9 |
| Benzyl chloride | CAR, HAP | 8 |
| Cumene | HAP | 6 |
| Nitrilotriacetic acid | CAR | 6 |
| Dimethylformamide | HAP | 5 |
| Phenol | HAP | 5 |
| Benzene | CAR, SDWA, HAP | 3 |
| Di(2‐ethylhexyl)phthalate | CAR, SDWA, HAP | 3 |
| Acrylamide | CAR, SDWA, HAP | 2 |
| Hydrogen fluoride (hydrofluoric acid) | HAP | 2 |
| Phthalic anhydride | HAP | 2 |
| Acetaldehyde | HAP | 2 |
| Acetophenone | CAR, HAP | 1 |
| Copper | SDWA | 1 |
| Ethylene oxide | CAR, HAP | 1 |
| Lead | CAR, SDWA, HAP | 1 |
| Propylene oxide | CAR, HAP | 1 |
| p‐Xylene | HAP | 1 |
| Number of products | 652 |
a Contains benzene, toluene, ethylene, and total xylene.
CAR, carcinogen; HAP, hazardous air pollutant; SDWA, Safe Drinking Water Act Regulated Chemical.
Hydraulic Fracturing Chemicals
The HVHF chemicals used for hydraulic fracturing of the Franchuk 44‐20 SWH well near Killdeer, North Dakota (L. Helms, personal communication). See Chapter 15 case studies about the Franchuk 44‐20 SWH well blowout, which occurred 2 September 2010.
| Chemical name | CAS number | Active ingredient concentration (%) | Hydraulic fracturing fluid concentration, μg l−1 |
| 2‐Ethylhexanol | 104‐76‐7 | 5 | 46.67 |
| Acetic acid | 64‐19‐7 | 60 | 109.58 |
| Acrylamide | 79‐06‐1 | 0.025 | 0.05 |
| Sodium 2‐acrylamide | 38193‐60‐1 | 27.6 | 50.41 |
| Alcohols, C10‐16, ethoxylated | 68002‐97‐1 | 1.8 | 3.29 |
| Alkyl dimethyl benzyl ammonium chloride (C12‐18) | 68391‐01‐5 | 6.25 | 3.7 |
| Alkyl dimethyl ethylbenzyl ammonium chloride (68% C12, 32% C14) | 85409‐23‐0 | 6.25 | 3.7 |
| Amine phosphonate 1 | Proprietary (ammonia salt of CAS number 34690‐00‐1) | 25 | 29.63 |
| Benzene, 1‐1′‐oxybis‐,tetrapropylene derivatives, sulfonated (Calfax DBA‐70) | 119345‐03‐8 | 7.5 | 70.01 |
| Boric oxide | 1303‐86‐2 | 10 | 560.07 |
| Canola oil | Not applicable | 20 | 1 120.13 |
| Colemanite | 1318‐33‐8 | 50 | 4 772.73 |
| Diethylenetriamine | 111‐40‐0 | 1.5 | 14 |
| Diethylenetriamine alkylbenzene sulfate | 40139‐72‐8 | 22 | 205.36 |
| Dihexamethylenetriaminepentakis (methylenephosphonic acid) [aka amine phosphonate] | 34690‐00‐1 | 24 | 28.45 |
| Disodium ethylenediaminetetraacetate | 38011‐25‐5 | 1.5 | 84.01 |
| Dowicil 75 | 4080‐31‐3 | 0.5 | 47.73 |
| Emulsion breaker | 29316‐47‐0 | 3 | 28 |
| Emulsion breaker | 153795‐76‐7 | 1.5 | 14 |
| Emulsion breaker | 68036‐95‐3 | 1.5 | 14 |
| Emulsion breaker | 30704‐64‐4 | 1.5 | 14 |
| Ethanol | 64‐17‐5 | 0.8 | 0.47 |
| Ethoxylated nonylphenol | 9016‐45‐9 | 5 | 280.03 |
| Ethoxylated sorbitan monostearate | 9005‐67‐8 | 0.847 | 1.55 |
| Formaldehyde | 50‐00‐0 | 0.04 | 0.05 |
| Glutaraldehyde | 111‐30‐8 | 25 | 14.82 |
| Heavy aromatic solvent naphtha | 64742‐94‐5 | 5 | 46.67 |
| Hydrochloric acid | 7647‐01‐0 | 2 | 2.37 |
| Hydroxypropyl guar | 39421‐75‐5 | 60 | 21 363.64 |
| Isopropyl alcohol (isopropanol) | 67‐63‐0 | 36.5 | 340.71 |
| Low odor paraffin solvent | 64742‐47‐8 | 23.3 | 42.55 |
| Methanol | 67‐56‐1 | 16 | 18.96 |
| Mineral oil | 64742‐46‐7(or 8) | 70 | 3 920.46 |
| Naphthalene | 91‐20‐3 | 1 | 9.33 |
| Organophilic clay | 68953‐58‐2 | 3 | 168.02 |
| Petroleum distillate blend | 64741‐84‐1 | 60 | 21 363.64 |
| Phosphoric acid | 7664‐38‐2 | 0.5 | 0.59 |
| Potassium carbonate | 584‐08‐7 | 40 | 2 240.26 |
| Potassium hydroxide | 1310‐58‐3 | 13 | 728.08 |
| Propylene carbonate | 108‐32‐7 | 1 | 56.01 |
| Sodium chloride | 7647‐14‐5 | 3.98 | 7.27 |
| Sodium glycolate | 2836‐32‐0 | 5 | 280.03 |
| Sodium hydroxide | 1310‐73‐2 | 1.5 | 84.01 |
| Sodium tetraborate pentahydrate | 12179‐04‐3 | 5 | 280.03 |
| Sorbitan monooleate | 1338‐43‐8 | 1.05 | 1.92 |
| tert‐Butyl hydroperoxide | 75‐91‐2 | 100 | 684.52 |
| Tetramethylammonium chloride | 75‐57‐0 | 50 | 466.72 |
| Tetrasodium ethylenediaminetetraacetate | 64‐02‐8 | 60 | 3 360.39 |
| Tetrasodium ethylenediaminetetraacetate | 64‐02‐8 | 0.014 | 0.03 |
| Triethanolamine hydrochloride | 637‐39‐8 | 4.62 | 2.74 |
| Trisodium ethylenediaminetetraacetate | 19019‐43‐3 | 1.5 | 84.01 |
| Trisodium nitrilotriacetate | 5064‐31‐3 | 1.5 | 84.01 |
| Xanthan gum | (various CAS #s listed) | 1 | 95.45 |
References
- National Institute of Standards and Technology (NIST) (2016). Methanol, Webbook; Retrieved 25 May 2017; http://webbook.nist.gov/cgi/cbook.cgi?Name=methanol&Units=SI.
- United States House of Representatives (2011). Chemicals Used in Hydraulic Fracturing, Committee on Energy and Commerce, Minority Staff, April, Washington, DC, 32 p.