The document provides information about a presentation on seismic surveys given by Rakesh Kumar. It lists the group members and discusses topics including the origin of oil and gas from plankton and cooking of organic matter, oil migration and traps, reservoir rocks, and seismic surveys. Seismic surveying involves firing sound waves into the earth and analyzing the reflected waves to image rock formations and determine potential locations for oil and gas reservoirs.

1. Petroleum Engineering
Presentation:-
Seismic Survey
Rakesh Kumar

2. Group Members
1. Rajat Sharma (R080114026)
2. Rakesh Kumar (R080114027)
3. Ram Lakhan Thakur (R080114028)
4. Ravi Ranjan Kumar (R080114030)
5. Rishabh Tripathi (R080114031)

3. Topics
1: Origin – How do oil and gas form?
2: Exploration and Production –
How do we find oil and gas and how is it produced?
 Chemistry
 Plankton
 Cooking
 Migration
 Oil Traps
 Reservoir Rocks
 Seismic Surveys

4. Origin (1): Chemistry
Crude Oil
• Oil and gas are made of a mixture of
different hydrocarbons.
• As the name suggests these are large
molecules made up of hydrogen atoms
attached to a backbone of carbon.
Hydrocarbon

5. Origin (2): Plankton
• Most oil and gas starts life as microscopic plants and animals
that live in the ocean.
Plant plankton Animal plankton

6. Origin (3): Cooking
As Black Shale is buried, it is heated.
Kerogen
Gas
Oil
Organic matter is first changed by the
increase in temperature into kerogen,
which is a solid form of hydrocarbon
Around 90°C, it is changed into a liquid
state, which we call oil
Around 150°C, it is changed into a gas
A rock that has produced oil and gas in
this way is known as a Source Rock

7. Origin (4): Migration
• Hot oil and gas is less dense than
the source rock in which it occurs
• Oil and gas migrate upwards up
through the rock in much the same
way that the air bubbles of an
underwater diver rise to the surface
• The rising oil and gas eventually gets
trapped in pockets in the rock called
reservoirs
Rising oil

8. Exploration and Production (1): Oil Traps
• Some rocks are permeable
and allow oil and gas to freely
pass through them
• Other rocks are impermeable
and block the upward passage
of oil and gas
• Where oil and gas rises up
into a dome (or anticline)
capped by impermeable rocks
it can’t escape. This is one
type of an Oil Trap.
Impermeable
Permeable
Dome Trap

9. Exploration and Production (2): Reservoir Rocks
• The permeable strata in an oil trap
is known as the Reservoir Rock
• Reservoir rocks have lots of
interconnected holes called pores.
These absorb the oil and gas like a
sponge
This is a highly magnified picture of
a sandy reservoir rock (water-filled
pores are shown in blue)
As oil migrates it fills up the pores
(oil-filled pores shown in black)

10. Exploration and Production (3): Seismic Surveys
• Seismic surveys are used to locate likely rock structures
underground in which oil and gas might be found
• Shock waves are fired into the ground. These bounce off layers
of rock and reveal any structural domes that might contain oil
Drill here!

11. What is Seismic Surveying?
• The seismic survey is one form of geophysical survey that aims at measuring the
earth’s geophysical properties by means of physical principles such as magnetic,
electric, gravitational, thermal, and elastic theories.
• Seismic survey techniques are used to build up an image of the rock formations
beneath the seabed during the first part of the exploration phase.
• This technique is used by oil & gas explorers to find the detailed images of rock
formation below the earth’s surface, and these information are used in determining
location & size of oil reservoirs.

12. Process
• It is same as we see in the case of bats,
which sends waves to locate it’s prey…
• Waves are reflected after striking a
surface and we can know it’s location, by
the intensity of reflected wave…

13. Seismic Surveying on Land
• In this sound waves are sent inside the
earth, known as “Seismic Waves”.
• Sound producing machines such as
Vibrator truck is used to produce
Seismic Waves.
• Explosives or vibrating plates
(Sledgehammers) generate the waves
and a line or grid of geophones records
them.
• Density changes between rock or soil
layers reflect the waves back to the
surface and the speed and strength
that the waves are reflected back
indicates what geological features lie
below.

14. Seismic Surveying on Land
• Those reflected waves are captured by
Geophones, and those waves are
recorded in a recording truck.
• Seismic images are produced by
generating, recording and analyzing
sound waves that travel through the
Earth.
• After images are helpful in determining
the best places to explore for oil and gas.

15. What is a marine seismic survey?
• Uses sound energy to map geological
structures under the seabed
• Vessels tow devices that use
compressed air to produce pulses of
high energy, low frequency sound
waves
• Sound waves can penetrate more than
6,000 metres below the sea floor
• Travel through the water and into the
rock layers beneath the seabed
• Bounce back to receivers
(“hydrophones”) that measure
strength and return time
15

16. 16
Types of seismic surveys
Two dimensional (2D): Uses one sound source and one set of receivers
Three dimensional (3D): Uses multiple synchronized sound sources and hydrophones
Four dimensional (4D): Uses multiple synchronized sound sources and hydrophones
with the added dimension of time (i.e.: a 3D survey is conducted multiple times over
the same location at different periods to compare data)
Geohazard or well site survey: Uses one sound source and one set of receivers towed
over a small area prior to drilling to check for possible hazards.
Verticial Seismic Profiles: Hydrophones are lowered into a drilled well and sound is
produced at the surface to give a detailed view of the geology near the well bore

17. What are the impacts of seismic surveys on marine life?
17
• Current research indicated there is minimal risk of mortality in marine mammals, fish
and invertebrates.
• Marine mammals, depending on species and proximity, can experience temporary
changes to hearing thresholds and in some extreme cases these effects can be
permanent.
• Laboratory research show no mortality among invertebrates (crab etc.) but showed
some non-life threatening physical effects.
• Governments, academics and industry continue to invest in research related to seismic
impacts to further broaden the body of knowledge.