HYDRAULIC FRACTURING: ITS EFFECTS AND
ITS ALTERNATIVES
Ujjwal1,S.M Saif2
Department of Petroleum Engineering, Gharuan Mohali, Punjab
Ujjwal,ujjwalk924@gmail.com,9501775759
SM Saif,smsaif875@gmail.com,9041350306
ABSTRACT
A pressurized fluid, used to fracture the rock is known as hydraulic fracturing
which is a technique of well stimulation. This process involves the high-
pressure of 'fracking fluid' injection into a wellbore to create cracks in the deep-
rock formations which increases the productivity of the producing zone. It has
some serious adverse effect on the environment as 95% of water along with
4.5% of sand and 0.5% of other additives are used and only 50% of water is
able to rise back to the surface which means only 50% of water can be recycled
and reused. We can live without hydrocarbons but we can’t live without water.
Due to this fracturing, water gets contaminated which causes severe effects on
the environment and due to this it has been banned in some countries like
France, Germany, Scotland etc.
However Hydraulic Fracturing has significantly increased global oil & gas
production and is currently the only available method to economically extract
hydrocarbons from tight reservoirs. This makes it necessary to explore possible
alternatives to hydraulic fracturing to help to reduce our future energy woes by
production through tight reservoirs. The technologies covered in our paper
include dynamic fracturing, fracturing with some liquefied gases, etc. The paper
will discuss the effects of hydraulic fracturing on the environment and the
various alternatives that can provide a solution to the same.
INTRODUCTION
The method or technique employed to remove the scale, surge or anything which is
blocking the pore and hindering the oil flow into the well bore is called well stimulation.
So hydraulic fracturing is a method of well stimulation in which the rock is fractured by
some pressurized fluid known as frac jobs. The main objective or purpose of doing
hydraulic fracturing is basically to increase the productivity of the producing zone. A
fracturing treatment consists of breaking down a producing section hydraulically with a
sand carrying fluid, the sand being used through prop, the resulting fracturing. When
the hydrostatic pressure is removed, small grains of hydraulic fracturing proppants
(sand) hold the fractures open. It also increases productivity in low permeability
formation by creating deep penetration fracture.
The very first experiment of this technique of well stimulation is done in the year 1947
and the first industrial use was done in the year 1949. And since than it has been used
for enhance oil recovery and stimulation purposes. As of 2015, 2.8 million “frac jobs”
had been performed over the world on oil and gas wells; over 1.2 million of those
within the U.S. These treatment is indispensable to achieve adequate flow rates tight
oil, tight gas, shale gas and coal scam gas wells.
1 HISTORY
1.1 Precursors
Fracturing is a method to stimulate hard rock oil wells years back to the 1860s. Nitro
glycerin detonations or nitro were used to increase or enhance the oil and natural gas
production. On 25th April, 1965, Civil war veteran, Col. Edward A. L. Roberts had
received a patent for exploding torpedo. It was implemented in Pennsylvania, New
York, West Virginia and Kentucky using liquid and also solidified nitroglycerin. Later,
the same method was applied to gas and water wells. Well stimulation with acid
instead of explosive fluids, came into the light in 1930s. Due to the acid etching,
fractures could not close completely which results in further productivity increase.
1.2 Oil and Gas Wells
The relationship between treatment pressure and well performance was studied by
Floyd Farris from Stanolind Oil and Gas Corporation. This study was prime basis of the
first hydraulic fracturing experiment which was conducted in 1947 by Stanolind at the
Hugoton gas field of southwestern Kanas in Grant Country. For this well treatment,
over 1,000 gallons of gelled gasoline and sand from the Arkansas River were injected
into the gas producing formation which was limestone at the 2,400 feet or
approximately 730 m. The experiment was not very successful as the deliverability of
the well did not change appreciably. This process was further described by J.B. Clark
in his published paper in 1948 who was also from Stanolind. In 1949, a patent was
issued on this process and the license was granted to Halliburton Oil Well Cementing
Company. On 17th March, 1949, the first two commercial fracturing treatment was
performed by Halliburton in Archer County, Texas and Stephens County, Oklahoma.
Since than, the hydraulic fracturing treatment has been used for stimulation of
approximately 1 million oil and gas wells.
1.3 Massive Fracturing
Massive fracturing which is also known as high volume hydraulic fracturing is a
technique which was firstly applied by Pan American Petroleum in the year 1968 in
Stephens Country< Oklahoma, USA. Definition of massive hydraulic fracturing varies
but it is generally reference fracturing treatments injecting greater than 150 short tons,
or 300,000 pounds approximately of proppant.
Starting in 1973, the massive hydraulic fracturing was used in more than thousands of
gas wells in the Green River Basin, the San Juan Basin, Denver Basin and the
Piceance Basin and in some other hard rock formations of western U.S.
2 PROCESS
According to United States EPA (Environmental Protection Agency), hydraulic
fracturing is a process used to stimulate oil, natural gas or geothermal energy well to
maximize the extraction. Environmental Protection Agency defines the broader
process including the acquisition source water, well stimulation, well construction and
waste disposal.
2.1 Method
A fracture due to hydraulic fracturing is formed by pumping fracking fluid into a
wellbore at the rate which is sufficient to increase pressure at target depth to exceed
the fracture gradient or pressure gradient of the rock. The fracture gradient is defined
as the increase of pressure per unit of depth which is related to density and usually
measured in bars, pounds per square inch or per square foot. The rock fractures and
the fracking fluid permeates the rock which is extending the crack further.
3 Chemicals used in hydraulic fracturing
Roughly 200 tankers are required to bring the water from the water resource which are
than transferred into the pumper truck in which water is mixed up with sand and
additives which are injected into the wellbore into which it breaks the compressive
strength of the rock and hence brings the fracture which increases the permeability
due to which oil and gas can flow out and hence we get our desired product. The
mixture of water, sand and additives is known as fracking fluid. The proportion of
water, sand and additives are 90%, 9.2% and 0.79% respectively. The sand used in
this fracking fluid is used to hold the fracture so that it doesn’t get clocked. The
additives used in this are acids, surfactants, gelling agent, cross linkers etc.
COMPOSITION OF THE FRACKING FLUID
(WATER+SAND+ADDITIVES)
3.1 Function and Properties of the Fracking Fluids
Injected Purpose Products used Notes
Substance
Water Fractures the Bore water, farm pond water or Volume of
coal when groundwater previously extracted water required
injected under from coal seams is often used is ~0.2 to
high pressure 1.3 ML per well
(USEPA 2011)
Proppant Keeps the Sand The latest
fractures open Resin-coated sand technology
once the high Ceramics advances in
pressure fluid proppants
is removed Bauxite (aluminium ore) include high
strength
ceramics and
sintered bauxite
Hydrochloric acid
Acid Dissolves Not all wells
calcite in the Muriatic acid require this
coal prior to treatment
fracturing Acetic acid because coal
seams do not
always contain
calcite
Gelling Increases the Guar gum Not all
Agent viscosity of the Starches hydraulic
Or fluid, to allow Cellulose derivatives fracturing uses
more proppant a gel; gel-free
Clay to be carried Polydimethyldiallylammonium fracturing is
Stabilisers into fractures chloride termed
(Claytrol) ‘slickwater’
Tetramethylammonium chloride
(Claytreat 3C)
Increases the
viscosity of
Crosslinker gelling agent Borate salt There are
Ethyl glycol different
crosslinkers for
Isopropanol different gelling
Disodium octaborate tetrahydrate agents
Boric acid
Boric oxide
Injected Purpose Products used Notes
Substance
Biocide Limits or Glutaraldehyde The natural
prevents 2,2-Dibromo-2-cyanoacetamide polymer gelling
growth of agents are
bacteria that (DBNPA) good food for
Tetrakis(hydroxymethyl)phosphoni
could damage bacteria so they
the gelling um sulfate (THPS, Magnacide encourage
agent 575) bacterial growth
bronopol (2-bromo-2- - biocides kill
nitropropane-1,3-diol) these bacteria
Sodium hypochlorite
Sodium thiosulfate
Boric acid
Caustic soda
pH buffer Keeps the pH Acetic acid Required for
of the fluid in a Sodium hydroxide the stability of
specified crosslinked
Potassium carbonate
range polymers
Sodium carbonate,
Breaker Chemically Hydrogen peroxides Only required if
break the Sodium persulfate a gel is used
bonds of the
gel in order to Diammonium peroxidisulphate
reduce the
viscosity back
to that of water
Corrosion Aloe resin
Scale n,n-dimenthyl formamide
Inhibitors Methanol
Nonyl phenol
Friction Reduce fluid Oxyalkylated alcohol
Reducers surface
tension
3.2 Use of fracturing chemicals
The fluids which are in hydro fracturing are used to force the fractures open as well as
to carry the ‘proppants’ materials that helps the fracture to keep it open. The
composition of fracking fluids varies depending on the site specific conditions. This
typically comprises approximately 97 to 99 percent water and sand with remaining
volume which is consisting of a variety of aditives. These include acids, biocides, pH
buffers, gelling agent and some other chemicals. The use of toluene, xylenes, benzene
and ethyl-bennzene is banned in Queensland and NSW.
4 ISSUES, IMPACTS AND EFFECTS
4.1 Issues
The process of well fracturing is far from begin. EPA estimated that 80-150 billion
gallons of water are used to fracture nearly 35,000 of wells each year in U.S. It is
approximately the annual consumption of water of 50 to 80 cities each with population
of 50,000 the fracture treatments in CBM wells require 60000 to 360,000 gallons of
water per well whereas deeper horizontal shale wells require 2-10 million Gallons of
water just to fracture a single well. Extraction of so much water for fracturing has raised
some serious concerns regarding the ecological impacts to the aquatic resources as
well as the deep treating of drinking water aquifers. It is estimated that the
transportation of 2-5 million gallons of water require roughly 1400 truck trips which is
also a concern as the transportation of so much water can also crates road repair
issues, localized air quality and safety.
4.2 Impacts
Due to these issues the hydraulic fracturing creates a large impact on the environment
which gives serious threat to the biological system. Only 50% of water comes out from
the well after fracturing which means only 50% of the total of 90% of water can be
recovered, recycled and reused. Water gets contaminated after this process and some
toxic chemicals are also used as additives which can cause a life threatning disease
called cancer. Due to all these issues and impact, some of the countries like France,
Germany, Bulgeria and Scotland had banned this highly controversial process.
The main environmental concerns which are associated with hydraulic fracturing are:
1. Sub-surface contamination
2. Surface contamination
3. Sand and Proppants
Sub-surface contamination: This can be minimized by simply limiting the
use of toxic chemicals which are used in fracking fluid, preventing increased
connections via the fractured growth between water supply aquifers and coal
seams and by maximizing the recovery of chemicals via flowback.
Surface contamination: At the surface, water flowback is either stored in
ponds or in temporary storage tanks or transported by pipelines to the water
treatment plants. There is the potential for leaks, spills and accidental release
due to pipeline or pond failure. The aSssessment of the risks are generally done
by reviewing the existing site of the environment, calculating hazards to
determine that which chemicals are of most concern, assessing the exposure
pathways and then we have to characterize the risks.
Sand and Proppants: Average 300,000 pounds of proppants are used in
conventional oil and gas wells , 75,000-320,000 pounds of proppants are used in the
treatment of coal bed fracture and more than 4 million pounds of proppants is used in
shale gas well which is per well data for the shale gas.
4.3 Effects
Hydraulic fracturing for gas can affect the environment because there are chances of
shale gas can mixed water can cause certain health problems as due to hydraulic
fracturing many chemicals like benzene, ethyl benzene and radioactive materials can be
produced by a well if taken in significant amount. Exposing the chemicals to ground
water can give long lasting effects. So, the chemicals should be treated before they are
disposed. A study by Cornell University shows that if the humans get exposed to these
fracking chemicals then it may cause illness, cancer or even death.
During transportation and cleanup steps of processing there is a maximum risk. As due
to mishandling the spillage occur which can pollute surface water. According to the GIS
analysis there is greater impact on surface water as sediment contamination and other
chemicals like friction reducers, scale removers, surfactants, PH controller etc. As these
chemicals has also adverse effect on the aquatic life.
It has two effects in the process of extraction.
4.3.1 Water containing methane is not good for drinking.
4.3.2 Also methane is greenhouse gas as it causes less polluting than the oil or coal
but we cannot ignore that it causes less pollution.
Fracking can also cause small earthquake and post fracking can also cause high
earthquakes. It is shown by recent studies. The transportation of hydraulic fracturing
material can cause air pollution also.
5 ALTERNATIVES TO HYDRAULIC FRACTURING
5.1 PROPANE GAS FRACTURING
In this method a gel is made using liquefied propane gas which is widely available. It is
also known as liquidfied propane fracturing or gas fracking. It is made without using
water and is developed by small company Gasfrac, Alberta. Also like water, propane gel
is pumped with high pressure into the shale formation so that cracks can release natural
gas. As same in this case, it also contain proppant which can hold cracks, allow the gas
to escape. As in this case, it works like disappearing at underground and due to
pressure and heat, the gel again changes to the vapour which can be recovered at top
and can be reused. In this case, propane gas does not carry the chemicals or drilling
fluid particles. It is still not patent yet and it is used 1000 times in Canada. “We leave in
the nasties in the ground, where they belong” said Lestz. Burnett, a person who runs a
programme named Environment Friendly Drilling System in Houstan research center
which is a new technology that keeps oil and gas environmentally safe. Burnett said that
instead of using water, it is also good for environment and also has a resonable cost.
There are only two research papers published in Society of Petroleum Enginners and in
the year 2009 and 2011. There is a need of more papers to be published to accept this
technology. It should become more efficient as when the propane gas leaves the
fracture, the water behind it can block the gas pathway. Also the no of trucks used in
propane gas are quarter than the used in hydraulic fracturing. So, the cost is reduced
and also cause less environment harm as well as low pollution production. As it has an
advantage that recovered propane gas can be resold but it is explosive and requires
special equipment to handle it. Husky energy is one of the largest energy company in
Canada used LPG for drilling and due to flash, an incident occur and three workers
suffered burn but no loss of life there. There is also a risk of leaking propane gas, so
there will be 20 propane sensors and infrared monitoring systems.
5.2 Pneumatic Fracturing
In shallow formations, this technique is considered to be effective. In this method we
inject air or any gas which the natural strength more than the compressive strength of
rock. This technique is used where the formation is water sensitive, brittle and
unconventional. This technique is effective as it prevents clay swelling. The best results
are given by gaseous nitrogen in brittle formation containing natural fractures and stay
self propped once pumping is done. This is possible as nitrogen is an inert gas as well
as compressible having low viscosity and makes a poor proppant carrier. As the density
of this gas is low so the main applications in cold bed methane, shale formations upto
5000ft (1524 meter) in depth. Formations should have low permeability ( less than
0.1md ) and low porosity( less than 4%).
5.2.1 Description of the technique
In this technique air (or nitrogen) is injected into the subsurface at the pressure more
than the compressive strength of rock. For an initiation of fracture there is no specified
theoretical depth as it will depend for much time the sufficient pressure can be provided.
In this technique the injection pressure is 2-3 times more than hydraulic fracturing. The
maximum depth achieved in pneumatic fracturing is about 60 meter. For fracturing less
than the 25 meter than use of proppants are advisable.
5.2.2 Potential advantages
In this the no chemical additives are required.
Water is also not required.
5.3 Cyrogenic fluid
Liquid carbon dioxide
It can be used in many ways
(1) For fracturing reservoir liquid CO2 can be used.
(2) For fracturing reservoir super-critical CO2 can be used.
(3) Foam based CO2 can be used.
In this technique we use liquid CO2 as fracturing fluid instead of using water. It may
be binary solution of N2 and CO2 for reducing cost or it pure CO2 can be used. It
was used as an additives since 1960s for improving recovery of the treating fluid.
Since ,1980s whole fluid can be 100% CO2.The properties of liquid CO2 makes it
identity depending on the temperature and pressure it an exists as solid, ga s and
liqiuid state. It is termed as super critical fluid above crtical temperature. It is stored
under 2MPa pressure and -35 celcius temperature in storage tank. But when is
pumped at pressure 3540 MPa and as the depth descreses , it again changes to
CO2 vapour when it returns to the surface.
In the superheated state of CO2, it is held above critical temperature i.e. 31.1
degree celcius and critical pressure i.e. 72.9 atmosphere than deep penetration is
achieved in shale formation and ho harm to formation.
REFERNCES:
SOURCE: Hydraulic fracturing (1.1, 1.2, 1.3, 2.1, 2.2)
SURCE: Background Review hydraulic fracturing technique (3.1, 3.2)
SOURCE: Background Review hydraulic fracturing technique (4.1, 4.2, 4.3)
SOURCE: L GANOSSI (5.1, 5.2, 5.2.1, 5.2.2)
SOURCE: By Anthony Brino, inside climate news, and Brian nearing Albany Times-
Union (5.1)
