| Natural
gas origins
Natural
gas is . . . natural. Most geologists believe it was formed
from decomposed plant and animal matter that accumulated over
millions of years. Layers of sand, dirt and mud covered the
decomposed matter, and eventually changed to rock. The buried
plants and animals decayed into tiny bubbles of colorless,
odorless gas that's now trapped in the pores of the rock.
Over 90%
of the natural gas we use comes from the United States and
most comes from the lower 48 states, including the Appalachians,
the southwest and offshore in the Gulf of Mexico. The only
way the gas can be released is by drilling a hole in the rock
to bring it out. To determine where to drill the well, geologists
study maps, aerial and infrared photographs and conduct seismic
studies.
Is the
gas ready to use when it comes out of the ground? No. The
gas that comes out of the well is usually not ready to go
directly into a pipeline. About one-third of all gas is found
with oil, so the oil and gas are separated at a nearby processing
station. Natural gas also can contain other hydrocarbons,
such as propane and butane, that are processed out and used
for other purposes.
Almost
one-third of our gas comes from offshore wells that are attached
to the seabed or that float on water. This offshore gas usually
comes to the surface carrying condensate and salt water. These
are taken out by equipment known as "slug catchers."
The gas
then travels through "scrubbers" where additional
water that's trapped in the gas is taken out. And finally,
the gas is dried and sent on to a compressor station where
the pressure is increased for long-distance travel through
pipelines.
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