Read about fracking

8 04 2013

A lot of excitement at the acs Spring meeting in NewOrleans about two things: Solar Fuel production and fracking. Read about the later in the commentary

Fracking: What Can Physical Chemistry Offer?

Arun Yethiraj and Alberto Striolo
20134, pp 687–690
The Journal of Physical Chemistry Letters 

Hydraulic fracturing (“fracking” for the language purists,
“fracing” for the practitioners) is the process where water
(with some additives) is pumped into shale formations to
fracture the rock and improve the extraction of crude oil and
natural gas.1,2 Pressures up to over 20 000 psi are applied
during one fracturing stage. Figure 1 reproduces a schematic of
the process. A well is drilled vertically down into the soil (up to
depths between 6000 and 10 000 feet − aquifers are usually at
depths lower than ∼1000 feet3). Once the well reaches the
payload, it is drilled horizontally much further (up to 10 000
feet) into the formation.4 Because of horizontal drilling, a
surface pad of approximately 6 acres is sufficient for exploring
and producing a subsurface formation that extends for up to
6000 acres.5 Within the shale formation, the well is lined with a
metal casing that contains small apertures for fracturing. Water
(with some additives) is then pumped into the well and goes
through the apertures at high pressure, thus fracturing the rock.
Once the hydraulic pressure is released, the “flow-back” water
flows back into the well and is removed. Several fracturing
stages (up to 30) can be performed within a single well, which
becomes functional. Natural gas or oil, if present in the treated
area, flows out and can be collected. Because of fracturing, the
cost of one well can range from $1 to 7 million.2
The economic benefits of hydraulic fracturing are undeniable.
Extraction from shale reserves has become economically
feasible. The process has made domestic natural gas cheap
and abundant6 and has increased even the domestic oil
production. North Dakota, as an example, has become the #2
producer of crude oil in the country. The natural gas byproduct
is in some cases wastefully burned off because the infrastructure
to transport it does not exist. In other cases, the availability of
economic natural gas (in particular, ethane) is triggering
significant investments from the chemical industry to enhance
domestic manufacturing. As another example, the American
Chemical Council estimates that a 25% increase in ethane
supply will generate $132 billion in new U.S. economic output.
With continued growth in hydraulic fracturing, the U.S.A. could
become self-sufficient in energy within the next 20 years, with
obvious global socio-economic consequences. It is even
expected that natural gas could be exported!



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