Getting and
Producing Liquid Natural Gas (LNG)
Figure 1: Hydraulic
Fracturing4
|
Natural gas, along with oil, is found in
deposits that form below the ground in geological formations that consist of
shales, which are tight rock formations that can be a mile or more below the
earth’s surface2. To obtain the gas deposits people must drill into
the subsurface using a combination of hydraulic fracturing and horizontal
drilling.
Before
drilling can start scientists use imaging technologies to locate the gas
reservoirs2. When
the reservoir is located drilling of the well can begin, which takes about 6 to
8 weeks2. Once completed, hydraulic fracturing (Figure 1) is used to
release the natural gas from the tight shale formation2. The natural
gas is then brought to the surface where it then gets transported to a pipeline
to be distributed for processing and use2.
Figure 2: LNG
Process5
|
Natural gas processing consists of several stages (Figure 2). First, the gas needs to be treated to remove
impurities such as carbon dioxide and organic sulfur compounds since too much
CO2 can raise the temperature at which the gas will freeze3. Once these compounds have been removed, the
gas must be dehydrated since the presence of water can cause the gas to freeze
during the liquefaction process3.
Mercury is then removed since it is corrosive and can damage the LNG
heat exchangers used in the liquefaction process3.
After all of the contaminants are
removed, the gas is cooled down by a variety of processes to a finished temperature of about
-260 F (-160 C). The finished product is
then stored at approximately atmospheric pressure and then eventually
transported.
The conversion of natural gas to
LNG is a process that reduces its volume by about 600 times1. This reduction
in volume is beneficial since the resulting product can be easily transported via
cargo ships in high abundance. Once delivered to its destination, the LNG is heated
to its gaseous state so it can be distributed to homes and businesses1.
Works Cited
1. Center for Liquefied Natural Gas. (2015). Basics.
Retrieved from About LNG.
2. Texas Natural Gas Now. (2015). How We Get It. Retrieved June
24, 2015
3. The University of Oklahoma. (n.d.). Refrigeration Cycles.
Retrieved from The University of Oklahoma.
4. Figure 1 taken from Total E&P Denmark B.V. (n.d.). What is
Hydraulic Fracturing (fracking)? Retrieved from Total E&P Denmark
B.V.: http://en.skifergas.dk/technical-guide/what-is-hydraulic-fracturing.aspx
5. Figure 2 taken from Goldboro LNG. (2012-2015). What is LNG?
Retrieved from Goldboro LNG: http://goldborolng.com/about-lng/what-is-lng/