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Hydraulic fracturing, or fracking as it’s more commonly referred to, is
used to stimulate the production of oil and gas from unconventional oil and
gas deposits - shales, coalbeds, and tight sands. These types of deposits
need to be stimulated because they have a lower permeability than conventional
reservoirs and require the additional stimulation for production.
Hydraulic fracturing involves drilling a well then injecting it with a
slurry of water, chemical additives and proppants. Wells are drilled and
lined with a steel pipe that’s cemented into place. A perforating gun is used
to shoot small holes through the steel and cement into the shale. The highly
pressurized fluid and proppant mixture injected into the well escapes and
create cracks and fractures in the surrounding shale layers and that
stimulates the flow of natural gas or oil. The proppants (grains of sand,
ceramic beads, or sintered bauxite) prevent the fractures from closing when
the injection is stopped and the pressure of the fluid is removed.
Proponents of hydraulic fracturing argue that fracking:
- Creates cheap domestic energy
- Replaces dirty coal-fired power plants
- Makes it easier to meet federal air and water quality
standards
- Reduces our dependence on foreign supplied oil
“Fracture stimulation is a safe and environmentally sound practice
based on the industry’s decades-long track record, as well as the conclusions
of government and industry studies and surveys.” Halliburton, a major
corporate proponent of fracking
Opponents of hydraulic fracturing have some serious concerns regarding:
- Contamination of the environment
- Threats to human health
- False promises of long-term economic benefits
Over the last several years there’s been a dramatic rise in the use of
hydraulic fracturing. As use of this technology has increased worries are
growing about fracking’s effect on our fresh water supply,
it’s easy to see why:
- Fracking just one well can use two to eight million
gallons of water with the major components being water (90%), sand or
proppants (8-9.5%), and chemicals (0.5-2%). One four million
gallon fracturing operation would use from 80 to 330 tons of chemicals
and each well will be fracked numerous times. Many of these
chemicals have been linked to cancer, developmental defects, hormone
disruption, and other conditions
- Cracked wells and rock movement frequently leak fracking
fluid and gases into nearby groundwater supplies. Fracturing fluid leakoff
(loss of fracturing fluid from the fracture channel into the surrounding
permeable rock) can exceed 70% of injected volume
- Methane concentrations are 17x higher in drinking-water
wells near fracturing sites than in normal wells. Hydraulic fracturing increases
the permeability of shale beds, creating new flow paths and enhancing
natural flow paths for gas leakage into aquifers
Here are a few excerpts from ‘Myths Versus Realities…Getting the facts
about Fracking’ published by The Council of Canadians.
- Research by the U.S. Environmental Protection Agency and
the U.S. Endocrine Disruption Exchange Inc. has demonstrated that
fracking fluids contain toxic substances known to cause serious health
impacts such as cancer and organ damage, and can have negative impacts
on neurological, reproductive and endocrine systems.
- A 2011 study by the U.S. Environmental Protection Agency
confirmed the clear link between fracking and water contamination.
- Contamination of fracking fluids from one well to
another – ‘fracturing communication incidents’ - has been documented in
British Columbia. On May 20, 2010, the British Columbia Oil and Gas
Commission (BC OGC) issued a safety advisory stating that they were
aware of 18 fracturing communication incidents. The BC OGC’s advisory
also confirmed that fracking fluids can return to the ground surface,
which poses a significant threat to water sources as chemicals could
leach into nearby watersheds.
- One study published in an academic journal by a
professor at Cornell University suggests that fracked gas emissions may
be worse than those associated with oil and coal.
- In a recent briefing titled Health Implications of
Fracking for Natural Gas in the Great Lakes-St. Lawrence River Basin,
Dr. Theo Colborne noted that some workers were required to sign
contracts preventing them from ever revealing their hourly wage or
health problems. They were not even allowed to call 911 in case of an
accident or a spill. Workers who suffered from hypertension,
fibromyalgia, chemical sensitivity, memory loss and depression could not
get worker’s compensation because they could not prove their medical
conditions were a result of chemical exposure.
As of 2010, it was estimated that 60 percent of all new oil and gas wells
worldwide were being hydraulically fractured. As of 2012, 2.5 million
hydraulic fracturing jobs have been performed on oil and gas wells worldwide,
more than one million of them in the United States – Wikipedia.
The fracturing fluids job is to create the fractures, hold them open, place
the proppants, and then lose viscosity to flow back up the wellbore. It has
to do all that without damaging the reservoir. Typical fluid types are:
- Conventional linear gels. These gels are cellulose
derivatives or guar (and its derivatives) based.
- Borate-crosslinked fluids are guar-based fluids
cross-linked with boron ions. These gels are used to carry proppants.
- Organometallic-crosslinked fluids use zirconium,
chromium, antimony, titanium salts to crosslink guar based gels. Gels
are broken down with appropriate breakers.
- Aluminium phosphate-ester oil gels. Aluminium phosphate
and ester oils are slurried to form cross-linked gel.
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