Marcellus Issues in West Virginia: An Introduction

Hydraulic Fracturing, part 2

This part will discuss the various types of products used for hydraulic fracturing and the chemicals used. There are links to MSDSs for products that have been utilized in hydraulic fracturing (mostly products used in West Virginia but also a few used in Ohio ).

A good place to begin one's search for information about the effects of various chemicals used in drilling and fracturing wells is The Endocrine Disruption Exchange web site.

The United States National Library of Medicine's online ChemIDplus database provides a wealth of information about chemicals. To search for items according to Chemical Abstract Service (CAS) numbers found on MSDS sheets and FracFocus disclosures, select "Registry Number" to search by and enter the number. On the resulting page select "Full Record" which provides synonyms, chemical structure, health information and more.

The EPA produced a report on hydraulic fracturing of coalbed methane wells that examined the components of a gel type fluid such as is used in fracturing horizontal Marcellus wells (full report or chapter 4 which is most pertinent). Some consider the science behind the report as flawed, but one of the results was not including diesel "class" of chemicals in the federal Safe Drinking Water Act hydraulic fracturing exemption. Industry, because of this exemption, has no restriction for the use of any other chemical.

Recently the EPA released a draft Guidance for the use of diesel "class" chemicals in hydraulic fracturing. West Virginia has no guidance and exercises no regulatory control over this group of chemicals. One of the problems is the Safe Drinking Water Act's imprecise language as to what chemicals exactly are included in the class..

Note when reading the MSDSs that exposure is most often considered to be through skin contact or breathing, not ingestion as would occur with groundwater contamination. Below is a description of the major types of products that are used in fracturing fluids along with example MSDSs. MSDS have also been collected for four specific well hydraulic fracturing fluids: the 2008 fracturing of a vertical well by Halliburton; a 2011 fracturing of a horizontal Marcellus well in Upshur county; a 2011 fracturing of a horizontal Marcellus well in Taylor county; and a 2011 fracturing of a horizontal Marcellus well in Wetzel county.

Hydrochloric Acid

A dilute hydrochloric acid (15%) is most commonly used for pretreating the formation after perforation, before hydraulic fracturing. The chloride in flowback comes from spent acid and/or brine. Other hydrochloric acid MSDS sheets show concentrations above or below 15% -- 5-10%, 10-30%, and 30-33%.

Biocide

Glutaraldehyde is the most commonly used biocide though it is probably not the safest for the environment. Accidental poisoning by glutaraldehyde is particularly prevalent for farmworkers. Here's a glutaraldehyde MSDS. Other chemicals are used as biocides, such as 2,2-Dibromo-3-nitrilopropionamide (a MSDS and another MSDS, both with a glycol carrier).

Corrosion Inhibitor

Corrosion inhibitors generally have methanol, a toxic chemical when ingested. Here's an example of an inhibitor's MSDS.

Friction Reducer

This MSDS contains petroleum distillates (CAS 64742-47-8), one of the chemicals that can fit within the diesel "class" (e.g., it can be used as a fuel).

Scale Inhibitor

This MSDS contains ethylene glycol which is a chemical that appears in a number of types of products used for hydraulic fracturing.

Gel

The most commonly used gel component is guar gum, a natural, food quality, product. A hydrocarbon solvent must be used before mixing the guar with water, to prevent clumping. The solvent used can range from relatively innocuous mineral oil to something like kerosene or diesel. Commonly MSDSs don't actually list the chemical name or CAS number of the solvent, using instead "proprietary ingredient" or a generic term such as "paraffinic solvent". Industry is being forced to use less toxic solvents in response to public concern. LGC-35 CBM has been used in West Virginia according to FracFocus as has WG-35 (which is guar alone). Here's a MSDS for a product with "petroleum distillate blend" as the solvent along with guar gum.

Crosslinker

The crosslinker strengthens the gel polymer. Here's a crosslinker MSDS.

Breaker

When fracturing has been completed, the breaker disrupts the gel's structure, causing it to fall apart. Without a breaker, the gel would clog the fractured voids and block the flow of natural gas. Here's a breaker MSDS and another using carbohydrates.

Other Types of Products

Surfactants are products that serve a variety of purposes -- defoaming, wetting, etc. Detergents are surfactants. Here's a Halliburton product, a Calfrac product, and another Halliburton product. This emulsion breaker contains hydrotreated light distillates, a diesel class chemical because it can be used as a fuel. This is a MSDS for a buffering agent. And this MSDS is for a product used for iron control.

 

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