List of Chemicals Used in Fracking
| Chemical Name | Common Name | Function & Chemical Purpose |
| Glutaraldehyde | Diswart | Biocide |
| Hydrochloric Acid | – | Acid |
| Hydrotreated Light Petroleum Distillate | – | Carrier for Borate and Zirconate (Crossl ... |
| Hydroxyethyl Cellulose | Guar Gum | Gelling Agent |
What is the purpose of acid fracturing?
In acid fracturing, acid is used to “etch” channels in the rock that comprise the walls of the fracture. Thus, the rock has to be partially soluble in acid so that channels can be etched in the fracture walls.
Why can’t acid fracturing be used on sandstone?
Thus, the rock has to be partially soluble in acid so that channels can be etched in the fracture walls. As such, the application of acid fracturing is confined to carbonate reservoirs and should never be used to stimulate sandstone, shale, or coal-seam reservoirs.
What is the difference between acid fracturing and proppant fracturing?
The main difference between acid fracturing and proppant fracturing is the way fracture conductivity is created. In proppant fracturing, a propping agent is used to prop open the fracture after the treatment is completed. In acid fracturing, acid is used to “etch” channels in the rock that comprise the walls of the fracture.
What type of fluid is used in acid fracturing?
The most commonly used fluid in acid fracturing is 15% hydrochloric acid (HCl). To obtain more acid penetration and more etching, 28% HCl is sometimes used as the primary acid fluid.
What acid is used in fracking?
hydrochloric acidThe answer: hydrochloric acid plays a key role in the hydraulic fracturing process. After the natural gas well's hole is bored, drillers will pump thousands of gallons of water mixed with acid down into the well.
What does hydrochloric acid do in fracking?
Acidizing involves pumping acid (usually hydrochloric acid), into the formation to dissolve some of the rock material to clean out pores and enable gas and fluid to flows more readily into the well. Some studies have shown that more than 90% of fracking fluids may remain underground.
Why do they use chemicals in fracking?
Chemicals Used in Fracking Acids, for example, are used to dissolve minerals to help fossil fuels flow more easily; biocides eliminate bacteria; gelling agents help carry proppants into fractures; and corrosion inhibitors prevent steel parts of the well from being damaged by fracking fluid.
What fluid is used in fracking?
Fracking fluid is 99.5% water and sand. 0.5% is made up of safe chemical additives, most of which are found in common household products, like toothpaste and makeup remover, or in the foods you eat.
Does acid break down oil?
Water easily dissolves other polar substances, like sodium chloride salt, but does not dissolve non-polar molecules such as oil. For the same reason, acids, which are polar molecules, generally do not dissolve oil.
What is injected into the ground during fracking?
These underground formations may range from deep sandstone or limestone, to a shallow soil layer. Injected fluids may include water, wastewater, brine (salt water), or water mixed with chemicals. The definition of a well is codified in the UIC regulations at 40 CFR 144.3.
Why is fracking fluid so toxic?
In hydraulic fracturing, operators inject fluid into shale formations to release natural gas and oil. During production, the well brings up a brine that carries the fingerprint of the rock formation below, including naturally occurring toxic or radioactive elements like selenium and radium.
What are the toxic chemicals used in fracking?
Toluene, ethylbenzene, and xylenes have harmful effects on the central nervous system. The hydraulic fracturing companies injected 11.4 million gallons of products containing at least one BTEX chemical between 2005 and 2009.
Is fracking water toxic?
However, the practice may come with a significant public health consequences, warn critics of fracking, noting that the process has the potential to contaminate drinking water supplies with toxic chemicals.
What 3 components make up fracking fluid?
Fracturing Fluid Contents Generally speaking, most formulas consist of 0.5 to 2 percent chemical additives and 98 to 99 percent water and sand. Although there are hundreds of chemicals that may be used in hydraulic fracturing, the vast majority of fracture jobs use a relatively small number of these chemicals.
What of chemicals make up fracking fluid?
About 90.0% of the frac fluid mixture is water and 9.5% is sand. The remaining 0.5% consists of chemical additives. The additives are compounds we encounter every day in common food additives, household cleansers and automotive antifreeze.
What are frac chemicals?
Fracking fluid (or frac fluid) is a chemical mixture used in drilling operations to increase the quantity of hydrocarbons that can be extracted. The fluid prevents corrosion of the well. It also lubricates the extraction process, and prevents clogs and bacterial growth, among other functions.
What is HCl in oil and gas?
Hydrochloric acid is a colorless inorganic chemical system with the formula H2O:HCl. Hydrochloric acid has a distinctive pungent smell. It is mainly produced as a precursor to vinyl chloride for PVC.
What is the contribution of hydraulic fracturing in oil production?
Hydraulic fracturing accounts for about half of current U.S. crude oil production. Even though hydraulic fracturing has been in use for more than six decades, it has only recently been used to produce a significant portion of crude oil in the United States.
What %HCl is used in oil and gas?
Hydrochloric acid with concentrations of 20° Baume (~ 31%) or 22° Baume (~ 35%) are most commonly used for applications in the Oil & Gas Industry and hydraulic gas fracturing (fracking) industry.
What is the purpose of acid fracturing?
In acid fracturing, acid is used to “etch” channels in the rock that comprise the walls of the fracture. Thus, the rock has to be partially soluble in acid so that channels can be etched in the fracture walls.
Why is formic acid used in fracturing?
On occasion, formic acid (HCOOH) or acetic acid (CH 3 COOH) is used because these acids are easier to inhibit under high-temperature conditions. However, acetic and formic acid cost more than HCl. Hydrofluoric acid (HF) should never be used during an acid fracturing treatment in a carbonate reservoir.
How does acid fracturing affect fracture conductivity?
The problem with acid fracturing that prevents its successful application in many reservoirs involves sustaining fracture conductivity over time. When the acid etches the fracture walls, the resulting fracture conductivity can be several orders of magnitude more conductive than similar treatments that use water-based fluids and propping agents. Fig. 4 presents data concerning fracture conductivity as a function of effective stress on the fracture and rock embedment strength. The embedment strength is easily measured and can be correlated with the compressive strength of the rock. As the compressive strength increases, the rock embedment strength increases. The data in Fig. 4 show that, when the embedment strength is less than 100,000 psi, large fracture conductivities, on the order of 10 to 50,000 md-ft, can be created during an acid-fracture treatment, as long as the effective stress on the fracture is 1,000 psi or less. However, once the effective stress on the fracture exceeds 5,000 psi, the fracture conductivity decreases substantially. As such, in deep limestone reservoirs in which the maximum effective stress on the fracture is much greater than 5,000 psi, an acid fracture will not stay open as the well is produced. In such cases, water-based fluids carrying propping agents should be considered as an alternative to acid fracturing.
What is the difference between acid fracturing and proppant fracturing?
The main difference between acid fracturing and proppant fracturing is the way fracture conductivity is created. In proppant fracturing, a propping agent is used to prop open the fracture after the treatment is completed. In acid fracturing, acid is used to “etch” channels in the rock that comprise the walls of the fracture. Thus, the rock has to be partially soluble in acid so that channels can be etched in the fracture walls. As such, the application of acid fracturing is confined to carbonate reservoirs and should never be used to stimulate sandstone, shale, or coal-seam reservoirs. Long etched fractures are difficult to obtain, because of high leakoff and rapid acid reaction with the formation. Acid fracturing works more effectively near the wellbore. Acid reacts with the small grains (which prevents the flow of fluid from the formation to the wellbore) and dissolves it into small particles.
What temperature is best for acid fracturing?
The best candidates are shallow, in which the reservoir temperature is less than 200°F and the maximum effective stress on the fracture will be less than 5,000 psi. Low temperature reduces the reaction rate between the acid and the formation, which allows the acid to penetrate deeper into the fracture before becoming spent. Because limestone reservoirs are ductile, a low effective stress on the fracture is required to maintain adequate fracture conductivity over the life of the well. In deep limestone reservoirs, in which problems exist with high bottomhole temperature and high effective stress on the fracture, water-based fluids with propping agents can be used successfully to stimulate the formation. In deep dolomite reservoirs that are less ductile than limestones, acid fracturing may work satisfactorily; however, proppant fracturing with water-based fluids may work also.
Why are long etched fractures so difficult to obtain?
Long etched fractures are difficult to obtain, because of high leakoff and rapid acid reaction with the formation. Acid fracturing works more effectively near the wellbore. Acid reacts with the small grains (which prevents the flow of fluid from the formation to the wellbore) and dissolves it into small particles.
How does fracture width affect acid penetration?
Figs. 2 and 3 illustrate how fracture width and formation temperature affect acid penetration in the fracture, respectively. In Fig. 2, as the fra cture width increases , the distance that unspent acid will reach in the fracture also increases. The distance increases because, in a wide fracture, there is less turbulence. This results in less mixing as the live acid moves down the fracture; therefore, the viscous and leakoff properties of the fracture fluid should be controlled to maximize fracture width. Fig 3 contains information concerning the effects of:
How does acid fracturing work?
Acid is squeezed into the reservoir under a pressure higher than formation breakdown pressure or natural fracture closure pressure. Thus fracture is formed in the reservoir, and grooving wall or trachydiscontinuity is generated due to the dissolution and etching of acid liquor on wall. After the external pressure is relieved, the fracture generated cannot be fully closed; thus, an artificial fracture with a certain geometric size and flow conductivity is finally formed, so that the condition of flow to the well will be improved and well productivity will be increased. The increase in well productivity by acid fracturing is displayed by the following:
How does acid fracturing increase the productivity of a well?
The increase in well productivity by acid fracturing is displayed by the following: 1. Forming fracture, increasing the area of oil and gas flow toward the well , improving oil and gas flow conditions, and increasing near-wellbore flowability. 2. Eliminating formation damage in the vicinity of the borehole wall. 3.
What is the difference between acid fracturing and matrix fracturing?
An acid fracturing treatment typically requires a much larger volume of acids than a matrix acidizing treatment does. Acid fracturing is generally applicable in low- to moderate-permeability carbonate reservoirs. Matrix acidizing is sufficient to remove near wellbore damage and to stimulate high-permeability reservoirs.
What is the process of fracturing fluid?
1. Injecting an acid fracturing fluid into the formation at a pressure sufficient to form fractures within the formation. The fluid comprises a sulfonate ester, a fluoride salt, a proppant, and water; the sulfonate ester is hydrolyzed to produce sulfonic acid. 2.
How is hydrofluoric acid produced?
Producing hydrofluoric acid in situ in the formation by reacting the sulfonic acid with the fluoride salt subsequent to injection of the acid fracturing fluid into the formation.
What is the name of the fluid that is injected into the formation of a fracturing fluid?
Injecting into the formation an acid fracturing fluid at a pressure sufficient to form fractures within the formation, the acid fracturing fluid comprising a sulfonate ester , a fluoride salt, a proppant, and water, the sulfonate ester being hydrolyzed to produce sulfonic acid.
How to make hydrofluoric acid in situ?
producing hydrofluoric acid in situ in the formation by reacting the sulfonic acid with the fluoride salt subsequent to injection of the acid fracturing fluid into the formation.
Why are chemicals used in fracking?
Chemicals are used in the fracking process to make the fracturing of shale and recovery of gas an efficient process. Their use eliminates the need for further processing of the recovered gas. If chemicals were not used, one would have to regularly carry out the tedious task of cleaning out the pipes due to deposition and precipitation of minerals, and also the action of bacterial byproducts. Also such depositions in the shale quarry itself would lead to inefficient recovery and re-entrapment of the natural gas. In addition, if friction reducers are not added, it would require more pressure and force to pump the water and sand mixture down to the rock bed. In the absence of clay stabilizers, there arises a possibility of the clay loosening and the tunnel collapsing. There is also a chance of decreased gas recovery due to the formation of emulsions.
What is the purpose of fracking fluid?
The water in the fluid acts as a transporting agent for the chemicals and the sand . The sand acts to keep the fissures, caused by the pressurized nature of the injected fluid, to remain open. The different chemicals kill bacteria and other microbes, and help in dissolving minerals found in the shale. With various possible chemicals that can be used, each company maintains its own tried and tested blend of chemicals to be used for the process. However, there are a few chemicals that are commonly and routinely used by all companies that carry out fracking. Each chemical serves a purpose and can be classified accordingly.
What is hydraulic fracturing?
Hydraulic fracturing (also known as hydrofracturing, hydrofracking, or fracking) involves injecting shale formations with pressurized fluids to release trapped oil and gas reserves. The fluid used for this purpose is a mixture of water, sand, and a variety of chemicals. The chemicals to be used are based on the type of shale formations surrounding ...
What happens after a well is fracked?
After a well has been fracked, it is usually rinsed or flushed with pressurized water. All the injected fluids are recovered to some extent, and treated and recycled to reduce the toxicity levels. Newer ways are also being researched for possible reuse of the injected fracking fluid. « Previous Post.
What is the process of extracting oil and natural gas from underground shale formations?
Fracking, or hydraulic fracturing, is a process of extracting oil and natural gas from underground shale formations, by inducing the formation of fissures along the shale rock.
Why does sand help with fissures?
The sand acts to keep the fissures, caused by the pressurized nature of the injected fluid, to remain open. The different chemicals kill bacteria and other microbes, and help in dissolving minerals found in the shale.
What would happen if friction reducers were not added?
In addition, if friction reducers are not added, it would require more pressure and force to pump the water and sand mixture down to the rock bed. In the absence of clay stabilizers, there arises a possibility of the clay loosening and the tunnel collapsing.
What is acid fracturing?
Acid fracturing is a production stimulation technique in which acids, injected at high pressures, are used to create and sustain flow channels in hydrocarbon formations with the sole purpose of increasing productivity.
Can you use acid fracturing on carbonate rocks?
Acid fracturing is not recommended for every rock. This is because the rock has to be soluble in the acid in the first place. Carbonate rocks are perfect candidates with acid fracturing treatments.
What is the purpose of hydrochloric acid in fracking?
Acids like hydrochloric acid are used in fracking fluids to dissolve the minerals in the rock, soil and sand below the ground. Acid is also used to dissolve parts of the rock to initiate cracking, according to FracFocus.
What is hydraulic fracturing?
Hydraulic fracturing, more commonly known as fracking, is the process of injecting water and other chemicals deep into the ground to create cracks or fissures and release fuel that can then be pumped out in wells built in the area.
How many chemicals are in fracking fluid?
Many additional chemicals are featured in each individual fracking fluid, FracFocus explained. Within a fluid, there may be dozens or hundreds of chemicals used to get the optimal solution. Not all are used for simple machine maintenance and disruption protection, like those previously mentioned. Many are integral to the extraction of fuels.
Why is fracking not talked about?
One area that is often not talked about because of the secrecy surrounding it is the chemicals that are used in the fracking fluid.
What is the best way to prevent corrosion?
Other acids, corrosion inhibitors and biocides like quaternary ammonium chloride and glutaraldehyde are used to prevent corrosion and eliminate corrosive bacteria. Many of the chemicals involved are used for mundane aspects of drilling, like preventing corrosion.
What is the best surfactant for fracking?
Surfactants like ethanol, methanol, lauryl sulfate and others alter the fuel's consistency to aid extraction following the drilling process as well as winterize the fracking fluid. Lauryl sulfate also acts as a non-emulsifier like isopropanol and ethylene glycol to prevent emulsions in the fracture fuel.
What percent of fracking fluid is made up of chemicals?
The remaining 0.5 percent of the fracking fluid is made up of chemicals.
What is Fracking used for?
Once geologists have identified an area that contains deposits such as sha le gas, a bore hole is drilled vertically into the earth to a depth of around one mile. The bore hole passes through the upper layers of the earth's crust, the water table and various subterranean layers until it reaches the shale.
What are the Main Chemicals used in Fracking?
Chemicals are added to the liquid at a rate of between 0.5 and 2.0% to perform various functions. Some are proppants such as sintered bauxite and zirconium oxide which help to keep the fissures open. Peroxodisulfate regulate the viscosity of the liquid and bactericides are added to prevent the gas becoming contaminated.
How does Fracking Work?
When the well has reached the shale layer, drill rods are used to create multiple horizontal shafts. These generally extend to approximately eight hundred metres but they can sometimes be several kilometres in length.
What is Fracking doing to the Environment?
The explosive characteristics of fracking effectively release gas that is embedded between the layers of shale. However, the shale gas that works its way to the surface consists primarily of methane. The greater part of it is collected but an estimated four percent escapes into the atmosphere .
What is Fracking doing to the Water Supply?
The fracking procedure uses literally millions of gallons of water to fracture the shale deposits. It is estimated that up to 40% of the waste water laden with the chemicals mentioned above, inevitably returns to the surrounding area's ground water supply. Major causes of concern are the safety of drinking water and the irrigation of agricultural land which could lead to contaminated crops.
What is Fracking Development in the Future?
Like so many inventions, the origin of fracking lies in warfare. In 1862, during the American Civil War, Colonel Edward Roberts was so impressed by the effectiveness of firing explosives along underground channels at the Battle of Fredericksburg that he patented the procedure. It provided the theory for fracking but sporadic experimentation in America didn't occur until after WWII.
How much water does fracking use?
The fracking procedure uses literally millions of gallons of water to fracture the shale deposits.
What is the best acid to use to clean wells?
There are different acids used to perform an acid job on wells. A common type of acid employed on wells to stimulate production is hydrochloric acids (HCI), which are useful in removing carbonate reservoirs, or limestones and dolomites, from the rock.
What is the purpose of acidizing a reservoir?
A type of stimulation treatment, acidizing is performed below the reservoir fracture pressure in an effort to restore the natural permeability of the reservoir rock. Well acidizing is achieved by pumping acid into the well to dissolve limestone, dolomite and calcite cement between the sediment grains of the reservoir rocks.
What is matrix acidization?
In this form of acidization, the acids dissolve the sediments and mud solids that are inhibiting the permeability of the rock, enlarging the natural pores of the reservoir and stimulating flow of hydrocarbons. While matrix acidizing is done at a low enough pressure to keep from fracturing the reservoir rock, fracture acidizing involves pumping ...
What are the two types of acid treatment?
There are two types of acid treatment: matrix acidizing and fracture acidizing. Well Acidizing Source: MPG Petroleum. A matrix acid job is performed when acid is pumped into the well and into the pores of the reservoir rocks.
How does matrix acidizing work?
While matrix acidizing is done at a low enough pressure to keep from fracturing the reservoir rock, fracture acidizing involves pumping highly pressurized acid into the well, physically fracturing the reservoir rock and dissolving the permeability inhibitive sediments .
Why are inhibitor additives added to a well?
In order to protect the integrity of the already completed well, inhibitor additives are introduced to the well to prohibit the acid from breaking down the steel casing in the well. Also, a sequestering agent can be added to block the formation of gels or precipitate of iron, which can clog the reservoir pores during an acid job.
What is the process of removing sediment from a well?
After an acid job is performed, the used acid and sediments removed from the reservoir are washed out of the well in a process called backflush.
Overview
- The main difference between acid fracturing and proppant fracturing is the way fracture conductivityis created. In proppant fracturing, a propping agent is used to prop open the fracture after the treatment is completed. In acid fracturing, acid is used to “etch” channels in the rock that comprise the walls of the fracture. Thus, the rock has to be partially soluble in acid so that chan…
Acid-Fracturing Candidate Selection
- In general, acid fracturing is best applied in shallow, low-temperature carbonate reservoirs. The best candidates are shallow, in which the reservoir temperature is less than 200°F and the maximum effective stress on the fracture will be less than 5,000 psi. Low temperature reduces the reaction rate between the acid and the formation, which allows the acid to penetrate deeper i…
Acid Fluids Used in Fracturing
- The most commonly used fluid in acid fracturing is 15% hydrochloric acid (HCl). To obtain more acid penetration and more etching, 28% HCl is sometimes used as the primary acid fluid. On occasion, formic acid (HCOOH) or acetic acid (CH3COOH) is used because these acids are easier to inhibit under high-temperature conditions. However, acetic and form...
Acid-Fracture Design Considerations
- In addition to Ref. 1, two papers provide the technology commonly used today to design acid fracture treatments. There are several unique considerations to be understood when designing acid fracture treatments. Of primary concern is acid-penetration distance down the fracture. The pad fluid is used to create the desired fracture dimensions. Then the acid is pumped down the fr…