Frack Fluid, Briefly
Hydraulic fracturing uses large volumes of extremely high pressure fluid injected deep below the ground to create fractures in the oil- or gas-bearing rock formation. These fractures are kept (propped) open with a “proppant” (or “propping agent”) - often a silica sand - allowing the hydrocarbons to flow from the formation to the well-bore. There have been many innovations in hydraulic fracturing. These past posts spot light several inventions and the patents that support them..
The fracking fluid contains major groups of chemicals that serve specific functions needed to achieve successful and efficient recovery of the underground hydrocarbons. A gelling agent or hydration aid reduces friction of the overall mixture with the well-site piping and well-bore by modifying the viscosity of the fluid. Biocides are used to control bacteria growth, thereby maintaining the integrity of the fluid, and the health of the formation. A crosslinker increases the viscoelasticity of the fracturing fluid, thereby improving proppant transport and distribution within the fractures created in the formation. Crosslinkers create a chemical bond link between the polymer chains used in the gel. Breakers work in opposition to crosslinkers - they reduce viscoelasticity and viscosity by breaking the polymer chain links and are used in cleanup of the fracture system. Surfactants (think soap or detergent) enhance recovery of the hydrocarbons by reducing their surface tension with the formation rock.
(A more user friendly version of the fracking fluids tables below are available at Way Better Patents.)
The US Department of Energy reported several years ago that a typical fracking fluid is composed by volume of:
| Constituent | Percent by volume |
|---|---|
| Water & sand | 99.51% |
| Acid | 0.123% |
| Friction reducer | 0.088% |
| Surfactant | 0.085% |
| Potassium chloride | 0.06% |
| Gelling agent | 0.056% |
| Scale inhibitor | 0.043% |
| pH adjusting agent | 0.011% |
| Breaker | 0.01% |
| Crosslinker | 0.007% |
| Iron control | 0.004% |
| Corrosion inhibitor | 0.002% |
| Biocide | 0.001% |
The exact blend of a frack fluid varies based on well-specific conditions, source water characteristics, and the vendor product used, and the individual treatments will use from 3–12 of the additives besides water and the propping agent. The purpose of the individual components is listed in the following table here.
| Additive type | Common Compound(s) | Purpose | Common Use |
|---|---|---|---|
| Diluted Acid (15%) | Hydrochloric acid or muriatic acid | Help dissolve minerals and initiate cracks in the rock | Swimming pool chemical and cleaner |
| Biocide | Glutaraldehyde | Eliminates bacteria in the water that produce corrosive byproducts | Disinfectant; sterilize medical and dental equipment |
| Breaker | Ammonium persulfate | Allows a delayed break down of the gel polymer chains | Bleaching agent in detergent and hair cosmetics, manufacture of household plastics |
| Corrosion Inhibitor | N,n-dimethyl formamide | Prevents the corrosion of the pipe | Used in pharmaceuticals, acrylic fibers, plastics |
| Crosslinker | Borate salts | Maintains fluid viscosity as temperature increases | Laundry detergents, hand soaps, and cosmetics |
| Friction Reducer | Polyacrylamide; Mineral oil | Minimizes friction between the fluid and the pipe | Water treatment, soil conditioner; Make-up remover, laxatives, and candy |
| Gel | Guar gum or hydroxyethyl cellulose | Thickens the water in order to suspend the sand | Cosmetics, toothpaste, sauces, baked goods, ice cream |
| Iron Control | Citric acid | Prevents precipitation of metal oxides | Food additive, flavoring in food and beverages; Lemon Juice ~7% Citric Acid |
| KCl | Potassium chloride | Creates a brine carrier fluid | Low sodium table salt substitute |
| Oxygen Scavenger | Ammonium bisulfite | Removes oxygen from the water to protect the pipe from corrosion | Cosmetics, food and beverage processing, water treatment |
| pH Adjusting Agent | Sodium or potassium carbonate | Maintains the effectiveness of other components, such as crosslinkers | Washing soda, detergents, soap, water softener, glass and ceramics |
| Proppant | Silica, quartz sand | Allows the fractures to remain open so the gas can escape | Drinking water filtration, play sand, concrete, brick mortar |
| Scale Inhibitor | Ethylene glycol | Prevents scale deposits in the pipe | Automotive antifreeze, household cleansers, and de-icing agent |
| Surfactant | Isopropanol | Used to increase the viscosity of the fracture fluid | Glass cleaner, antiperspirant, and hair color |
Source: Modern Shale Gas Development in the United States: A Primer. USDOE, NETL. 2009.
How do the ingredients of Halliburton’s CleanStim fracking fluid compare to the generic list above?
| CleanStim Constituent | Common Uses |
|---|---|
| Enzyme | Soybean Paste, Fruit Juices and Nectars, Laundry Detergent, Dishwasher Detergent, Toilet Cleaner, Industrial Pulp and Paper Processing Aid |
| Ethoxylated Sugar-Based Fatty Acid Ester | Synthetic Food Flavoring Substance, Natural Baby Wipes, Baby Wash and Shampoo |
| Inorganic Acid | Cheese, Alcoholic Beverages, Wheel Cleaner, Rust Dissolver, Dishwashing Detergent |
| Inorganic Salt | Food Starch – Modified, Water Clarifier, Fish Tank Water Treatment |
| Maltodextrin | Sweetener, Glaze and Icing Sugar, Coconut Milk and Coconut Cream, Shower Gel |
| Organic Acid | Fruit Juice, Dishwasher Cleaner, All-Purpose Cleaner, Hand Soap |
| Organic Ester | Liquid Egg Products, Food Resinous and Polymeric Coatings, Hairspray |
| Partially Hydrogenated Vegetable Oil | Confectionary Chocolate Coating, Hair Detangler, Body Lotion, Lip Liner, Soap, Lotion, Cream and Other Skin Care Formulations |
| Polysaccharide Polymer | Canned Fish, Processed Cheese, Dairy-Based Desserts and Drinks, Beer, Toothpaste |
| Sulfonated Alcohol | Egg White Solids, Marshmallows, Dishwashing Liquid, Home Dilutable Cleaner, Shampoo, Acne Scrub, Shaving Cream, Liquid Hand Soap |
In part 2 we’ll look at some fracking fluid inventions from Halliburton and other companies that are intended to address concerns about potential environmental and human health effects of frack fluid constituents.
