Wednesday, February 20, 2013

Fracking Fluids #1

There has been a recent flurry of media attention on Halliburton’s ‘CleanStim’ hydraulic fracturing (aka ‘fracking’, fracing’, or ‘hydrofracking’) fluid that the company says is derived from food industry products. Halliburton’s CleanStim fluid was actually released for use in 2010. What is the purpose of frack fluid? What’s in it?

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:

ConstituentPercent by volume
Water & sand99.51%
Friction reducer0.088%
Surfactant 0.085%
Potassium chloride 0.06%
Gelling agent 0.056%
Scale inhibitor0.043%
pH adjusting agent 0.011%
Breaker 0.01%
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 typeCommon Compound(s)PurposeCommon Use
Diluted Acid (15%)Hydrochloric acid or muriatic acidHelp dissolve minerals and initiate cracks in the rock Swimming pool chemical and cleaner
BiocideGlutaraldehydeEliminates bacteria in the water that produce corrosive byproducts Disinfectant; sterilize medical and dental equipment
BreakerAmmonium persulfateAllows a delayed break down of the gel polymer chains Bleaching agent in detergent and hair cosmetics, manufacture of household plastics
Corrosion InhibitorN,n-dimethyl formamidePrevents the corrosion of the pipe Used in pharmaceuticals, acrylic fibers, plastics
CrosslinkerBorate saltsMaintains fluid viscosity as temperature increases Laundry detergents, hand soaps, and cosmetics
Friction ReducerPolyacrylamide; Mineral oilMinimizes friction between the fluid and the pipeWater treatment, soil conditioner; Make-up remover, laxatives, and candy
GelGuar gum or hydroxyethyl celluloseThickens the water in order to suspend the sand Cosmetics, toothpaste, sauces, baked goods, ice cream
Iron Control Citric acidPrevents precipitation of metal oxidesFood additive, flavoring in food and beverages; Lemon Juice ~7% Citric Acid
KClPotassium chlorideCreates a brine carrier fluidLow sodium table salt substitute
Oxygen ScavengerAmmonium bisulfiteRemoves oxygen from the water to protect the pipe from corrosion Cosmetics, food and beverage processing, water treatment
pH Adjusting AgentSodium or potassium carbonateMaintains the effectiveness of other components, such as crosslinkersWashing soda, detergents, soap, water softener, glass and ceramics
ProppantSilica, quartz sandAllows the fractures to remain open so the gas can escapeDrinking water filtration, play sand, concrete, brick mortar
Scale InhibitorEthylene glycolPrevents scale deposits in the pipeAutomotive antifreeze, household cleansers, and de-icing agent
SurfactantIsopropanolUsed to increase the viscosity of the fracture fluidGlass 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.