2. it is colorless, shapeless, and odorless
in its pure form.
natural gas consists of mainly Methane
& it is clean burning and emits lower
levels of potentially harmful
byproducts into the air. it can also
include ethane, propane, butane and
pentane.
3. Typical Composition of Natural Gas
Methane CH4 70-90%
Ethane C2H6
0-20%Propane C3H8
Butane C4H10
Carbon Dioxide CO2 0-8%
Oxygen O2 0-0.2%
Nitrogen N2 0-5%
Hydrogen
sulphide
H2S 0-5%
Rare gases A, He, Ne, Xe trace
4.
5.
6.
7. The distinctive “rotten egg” smell that we
often associate with natural gas is actually an
odorant called mercaptan that is added to the
gas before it is delivered to the end-user.
Mercaptan aids in detecting any
leaks. Natural gas is considered 'dry' when it is
almost pure methane, having had most of the
other commonly associated hydrocarbons
removed. When other hydrocarbons are
present, the natural gas is 'wet'.
8. Natural gas can be measured in a number of
different ways. As a gas, it can be measured
by the volume it takes up at normal or
standard temperatures and pressures,
commonly expressed in cubic feet.
Production and distribution companies
commonly measure natural gas in thousands
of cubic feet (Mcf), millions of cubic feet
(MMcf), or trillions of cubic feet (Tcf).
STP: 1 atm. & 15 C.
NTP: 1 atm. & 0 C.
9. natural gas is commonly measured and
expressed in British thermal units (Btu).
One Btu is equivalent to the amount of
natural gas that will produce enough
energy to heat one pound of water by one
degree at normal pressure. To give an idea,
one cubic foot of natural gas contains about
1,027 Btu.
10. Problem: what is the quantity of liquids in
the following gas sample, p=900 psig, T=30
C?
11. The Formation of Natural Gas
The most widely accepted theory
says that fossil fuels are formed
when organic matter (such as the
remains of a plant or animal) is
compressed under the earth, at
very high pressure for a very long
time.
12. At low temperatures (shallower
deposits), more oil is produced relative
to natural gas. At higher temperatures,
however, more natural gas is created, as
opposed to oil.
a great deal of this methane will rise up
into geological formations that 'trap' the
gas under the ground. These formations
are made up of layers of porous,
sedimentary rock (kind of like a sponge
that soaks up and contains the gas), with
a denser, impermeable layer of rock on
top.
14. 1- The Exploration
it must be remembered that the process of
exploring for natural gas and petroleum
deposits is rife with uncertainty and trial-
and-error, simply due to the complexity of
searching for something that is often
thousands of feet below ground.
15. Seismic Exploration
Arguably the biggest breakthrough in
petroleum and natural gas exploration
came through the use of basic seismology.
Seismology refers to the study of how
energy, in the form of seismic waves,
moves through the Earth's crust and
interacts differently with various types of
underground formations.
16. Onshore Seismology
In practice, using seismology
for exploring onshore areas
involves artificially creating
seismic waves, the reflection
of which are then picked up
by sensitive pieces of
equipment called
'geophones' that are
embedded in the ground.
17. Recently, due to environmental concerns
and improved technology, it is often no
longer necessary to use explosive charges
to generate the needed seismic waves.
Instead, most seismic crews use non-
explosive seismic technology to generate
the required data. This non-explosive
technology usually consists of a large heavy-
wheeled or tracked-vehicle carrying special
equipment designed to create a large
impact or series of vibrations.
19. Offshore Seismology
The same sort of process is used in offshore
seismic exploration. When exploring for natural
gas that may exist thousands of feet below the
seabed floor, which may itself be thousands of
feet below sea level, a slightly different method
of seismic exploration is used. Instead of trucks
and geophones, a ship is used to pick up the
seismic data and hydrophones are used to pick
up seismic waves underwater.
20.
21. Exploratory Wells
The best way to gain a full understanding of
subsurface geology and the potential for
natural gas deposits to exist in a given area is to
drill an exploratory well. This consists of digging
into the Earth's crust to allow geologists to
study the composition of the underground rock
layers in detail. In addition to looking for
natural gas and petroleum deposits by drilling
an exploratory well, geologists also examine the
drill cuttings and fluids to gain a better
understanding of the geologic features of the
area.
22. APPRAISAL WELLS
Yet to prove through Exploratory well and
the presence of oil in the area of what is
needed to determine the area of the
contained reservoir for this oil, therefore, is
drilling additional wells at distances of up
to 2000 meters from the exploration well is
these wells and tests are performed by
more than the cost of the wells prior to
that they are digging.
23. DEVELOPMENT WELLS
If it is proven from the results of wells evaluation
and a tank of petroleum in the region contains
large balances can output them economically
would not mind drilling additional testing more
cost-called well development can be obtained
more accurate data and detailed and these wells
are designed to serve productivity wells later.
The results of each test wells in addition to the
results of geological maps can be made a rough
estimate of the quantity of oil or gas or both in
the reservoir
24. 2- The Extraction
Once a potential natural gas deposit has
been located by a team of exploration
geologists and geophysicists, it is up to a
team of drilling experts to actually dig
down to where the natural gas is thought
to exist.
the process of drilling for natural gas is
applied onshore and offshore
28. 3- The Production
is actually lifting the natural gas or oil out
of the ground and processing it for
transportation. the process of taking raw
natural gas from underground formations
and processing it into pipeline quality gas,
ready for transportation
29. Well completion:
Once a natural gas or oil well is drilled, and
it has been verified that commercially viable
quantities of natural gas are present for
extraction, the well must be 'completed' to
allow for the flow of petroleum or natural
gas out of the formation and up to the
surface.
30. This process includes strengthening the
well hole with casing, evaluating the
pressure and temperature of the formation,
and then installing the proper equipment
to ensure an efficient flow of natural gas
out of the well.
31. Completing a well consists of a number of
steps; installing the well casing, completing
the well, installing the wellhead, and
installing lifting equipment or treating the
formation should that be required.
32. 4- Natural gas processing
natural gas found at the wellhead, although still
composed primarily of methane, is by no means as
pure. Raw natural gas comes from three types of
wells: oil wells, gas wells, and condensate wells.
Natural gas that comes from oil wells is typically
termed 'associated gas'. This gas can exist separate
from oil in the formation (free gas), or dissolved in
the crude oil (dissolved gas). Natural gas from gas
and condensate wells, in which there is little or no
crude oil, is termed 'nonassociated gas'.
33. Methane commonly exists in mixtures with
other hydrocarbons; principally ethane,
propane, butane, and pentanes. In addition,
raw natural gas contains water vapor, hydrogen
sulfide (H2S), carbon dioxide, helium, nitrogen,
mercury and other compounds.
Natural gas processing consists of separating all
of the various hydrocarbons and fluids from the
pure natural gas, to produce what is known as
'pipeline quality' dry natural gas.
38. 5- The Transport
Pipelines can be characterized as interstate
or intrastate. Interstate pipelines carry
natural gas across state boundaries, in
some cases clear across the country.
Intrastate pipelines, on the other hand,
transport natural gas within a particular
state.
39. 6- The Storage
There are basically two uses for natural gas in
storage facilities: meeting base load
requirements, and meeting peak load
requirements. As mentioned, natural gas storage
is required for two reasons: meeting seasonal
demand requirements, and as insurance against
unforeseen supply disruptions. Base load storage
capacity is used to meet seasonal demand
increases. Base load facilities are capable of
holding enough natural gas to satisfy long term
seasonal demand requirements.
40. Peak load storage facilities, on the other
hand, are designed to have high-
deliverability for short periods of time,
meaning natural gas can be withdrawn
from storage quickly should the need arise.
Peak load facilities are intended to meet
sudden, short-term demand increases
41. Natural gas is usually stored underground,
in large storage reservoirs. There are three
main types of underground storage:
depleted gas reservoirs, and salt caverns. In
addition to underground storage, however,
natural gas can be stored as liquefied
natural gas (LNG). LNG allows natural gas to
be shipped and stored in liquid form,
meaning it takes up much less space than
gaseous natural gas.
42. 7- The Distribution
is the final step in delivering natural gas to
customers. While some large industrial,
commercial, and electric generation customers
receive natural gas directly from high capacity
interstate and intrastate pipelines (usually
contracted through natural gas marketing
companies), most other users receive natural
gas from their local gas utility, also called a local
distribution company (LDC).
43. 8- The Marketing
Natural gas marketing may be defined as
the selling of natural gas.
Marketing natural gas can include all of the
intermediate steps that a particular
purchase requires; including arranging
transportation, storage, accounting, and
basically any other step required to
facilitate the sale of natural gas.
