Chemistry of Fracking: Chemicals and Pressure to Harvest Natural Gas

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Fracking uses chemicals to extract natural gas. Image courtesy of energy.gov

Fracking uses chemicals to extract natural gas. Image courtesy of energy.gov

Fracking for natural gas has become a big business in North America, and it stands to become a major contributor to the alternative energy business throughout the world.

The technique of extracting natural gas from shale has interesting history with the origins beginning in the late 1970s.

Fracking: A Brief History

Geologists knew that shale contained oil and natural gas deposits before the 1970s energy crisis, but the gas shortages were the force behind the search for new ways to extract ‘hard to obtain oil.’

One new method was extracting the more elusive oil deposits was by using high-pressure steam. Other initial attempts to recover petroleum and gas from shale involved a process known as retorting (heat-processing individual shale rocks). The process of retorting proved inefficient and too costly—thus the energy business responded with numerous patents (inventions) that adapted steam technology for shale.

What is Fracking?

Fracking, also known as ‘fractioning’ (obtaining the trapped natural gas) is the application of high pressure water laced with a cocktail of organic and inorganic compounds to force the natural gas from under the ground. The resulting mixture of compounds that come from the ground contains methane and a mixture of petroleum-based organics and inorganics.

The present technology utilizing fracking comes from the long history of petroleum; it employs the chemistry associated from fine chemical synthesis, geochemical analysis of shale, the physical chemistry of high pressure water/steam and treatment of chemical waste.

High pressure water begins the process of fracturing the shale. The organic/inorganic cocktail makes the methane embedded in the rock solubilize, or easier to dissolve. According to the US EPA progress report, Study of the Potential Impacts of Hydraulic Fractioning on Drinking Water Sources, the components of the organic/inorganic cocktail are approximately  80% water, 15% sand, and between 1 and 2 percent of solubilizing components. To far lesser degree, there are organic and inorganic acids and a proprietary component based upon geologic and geographic location.

Patent disclosures seem to indicate that different types of shale call for varying amounts organic chemicals that help to extract the ‘wanted components’ from the shale.

From the patent held by Hercules Incorporated—which is US patent number, 7,384,892 of June 10, 2008—the inventors claim the following:

A water-based drilling fluid composition comprising water and at least one rheology modifier and/or fluid loss control agent, and at least one other ingredient selected from the group consisting of polymeric additive, inorganic salts, dispersants, shale stabilizers or inhibitors, weighting agents, and finely divided clay particles, depending upon the desired attributes, wherein the rheology modifier and/or the fluid loss control agent comprises carboxymethylated raw cotton linters (CM-RCL) and/or salts thereof, wherein the polymeric additive and/or dispersants exclude polycarboxylic selected from the group consisting of a homopolymer of acrylic acid, a homopolymer of methacrylic acid, a copolymer of acrylic acid and methacrylic acid, and a water-soluble salt of any of the foregoing acids, wherein the polycarboxylic acid has a number average molecular weight not exceeding 3,000, and wherein the CM-RCL is prepared from raw cotton linters containing about 80-85% cellulose, about 1.5-2.5% lignin and about 2.5-3.5% hemicellulose.

In plain English, they claim to be have invented a water-based cocktail that serves to ‘loosen and solvate’ the organic species within the rock matrix. However, the cocktail may include the following:

  • Hydrochloric acid: Loosens and dissolves iron species in the rock matrix.
  • Acetic acid: Loosen and dissolve organic species in rock matrix
  • Methanol: D: Dissolves iron ions, and surrounds them with solvent.
  • Propargyl alcohol: Inhibits corrosion.
  • Petroleum distillates: These propietary organics and inorganics are based upon the geographic/geologic drill site.
  • 2,2-Dibromo-3-nitropropionamide: A biocide pretreatment of water to kill bacteria.
  • Zinc, nickel, tin or aluminum metal ions: These metals help extract organic materials, including methane, benzene, naphthalene, and phenol, from the shale.

The fracking chemical cocktail ingredients are only a partial list that, upon further investigation, would tally into possibly hundreds of compounds. As is the case with ‘real world chemistry,’ each fracking site presents a different set of problems that are addressed with the appropriate technology.

Fracking Brine

The brine that the process extracts along with the methane is laden with organic compounds, toxic metal ions, and organic-loving bacteria. Therein lies the difficulty for individuals who live near fracking sites. As is often the case, the water table may be disturbed with toxic metals or one or more of the organic compounds the fuel company used to extract the methane. As a result, getting to the bottom of well water purity may take an army of lawyers or environmentalists.

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