I hv made this ppt as a group leader hope it would be beneficial

1. IN THE NAME OF ALLAH, THE MOST GRACIOUS, THE MOST
MERCIFUL

2. Department of Petroleum and Natural Gas Engineering
2nd term 2nd year 11-Batch
Presentation by Group no. 09
Subject:- Petroleum Geology and Exploration
Teacher:- Mr. Faisal Hussain Memon
Group leader:-Abdul Basit (K-11PG46)
Group Members:-Ahsan Ali (K-11PG91) Shafiullah Sheikh (K-11PG83)
Muhammad Yasin (K-11PG36)

3. Topics…!
1. Origin of petroleum by M.Yasin
2. Petroleum traps by Shafiullah Shaikh
3. Abnormal pressure by A.Basit
4. Exploration techniques by Ahsan Ali

5.  No any particular origin of petroleum.
 Some geologist believed , source material
deposited on shale and transforms into
petroleum.
 Some concepts assumes for oil
transportation along with undergoing
circulating water.

6. • Origin of petroleum is based on two
theories
1. Organic theory
2. Inorganic theory

7. Organic theory
95% scientists believe in the organic theory.
Organic theory commands that the oil and gas
are formed from the remains of
plants, animals and insects.
Some believe that it is formed from the
dinosaurs.
Some are giving its credit to small organisms
living in earth like ants.
Some believe that it is formed due to marine
organisms.
Some regard this as the convergence of
phytoplankton into petroleum.

8. Hydrocarbon formed from dinosaurs

9. Inorganic theory
 Only 5% scientists believe in inorganic theory.
 In 1928 Fredic Wohler discovered urea from
inorganic material.
He proved that we can get organic compound
from inorganic compound.

11. Petroleum Traps
• A trap is an arrangement of rock layers that
contains an accumulation of hydrocarbons.
• The trap consists of an impermeable layer of
rock above a porous, permeable layer
containing the hydrocarbons.
• The impermeable layer is termed as caprock.
• Traps come in all shapes, sizes and types.

12. Mechanism of trap

13. Classification of traps
• Geologists have divided traps into two basic
groups:
1. Structural Traps
2.Stratigraphic Traps

14. Structural Traps
• Structural traps are mostly formed by folding
or faulting of reservoir rocks.
• Structural traps are the most important type
of trap as they represent the majority of the
world's discovered petroleum resources.
• Some of the most common structural traps
are:
i. Anticlinal traps
ii. Fault traps
iii. Salt dome traps

15. i. Anticlinal traps:-
A trap whose closure is controlled by the presence of an anticline.
ii. Fault traps:-
A fault trap, as name suggests, will be formed by the movement of
rock along a fault line.
iii. Salt dome trap:-
A salt dome trap will be formed when a thick bed
of evaporite minerals (mainly salt, or halite) found at depth
intrudes vertically into surrounding rock strata.

16. Types

17. Stratigraphic traps
• A stratigraphic trap is caused either by a
nonporous formation sealing off the top edge
of a reservoir bed or by a change of porosity
and permeability within the reservoir bed
itself.
OR
• A stratigraphic trap accumulates oil due to
changes of rock character rather than faulting
or folding of the rock.

18. Stratigraphic traps
i. Unconformity
ii. Reef
iii. Pinch-out

19. i. Unconformity trap:-
A type of hydrocarbon trap whose closure is controlled by the
presence of an unconformity.
ii. Pinch out
A porous reservoir rock encased within an impermeable seal
such as shale; and the rock will not leave its original formation.

21. Background:-
In some reservoirs the pressure is not in
balanced condition means the pressure is not
normal pore pressure i.e. 0.465 psi/ft.
This will affect the behavior of reservoir during
production or drilling.
It is a very important consideration in many
aspects of well planning and operations.
The pressure of the fluid in the pore space (the
pore pressure).
Dependent on the density of the fluid & depth
of the pressure measurement.

22. Abnormal Pressure
Which is greater or less than normal
pressure.
Normal pore pressure gradient is 0.465
psi/ft.
The magnitude of the pressure in the
pores of a formation, known as the
formation pore pressure (or simply
formation pressure).

23. Subnormal Pressure
• An under pressured (subnormal) system
occurs when the formation pore pressure
is less than the normal pressure, 0.465
psi/ft.
Origins
1. Thermal Expansion
2. Formation forshoreting
3. Depletion
Effect
Occurrence of kick

25. Over pressured Pressure
• An over pressured system occurs when
the formation pore pressure is greater
than the normal pressure, 0.465 psi/ft.
Origins
1. Incomplete Compaction
2. Faulting
3. Salt dome zone
Effect
Lost circulation zone

28. Normal and Abnormal Pore Pressure
Normal Pressure Gradients
West Texas: 0.433 psi/ft.
Gulf Coast: 0.465 psi/ft.
Depth, ft.
Abnormal
Pressure
Gradients
10,000’
Pore Pressure, psig

29. Fracture Gradient
Pore Pressure
Gradient

30. Detection
• 1. Drilling Parameters
i. ROP
ii. WOB
• 2. Drilling mud
i. Pit level will increase
• 3. Drilled Cuttings
Change in composition

32. Oil Exploration Methods
• There are three commonly employed methods
for oil exploration
• 1) Geological
• 2) Geophysical
• 3) Geochemical

33. Geophysical Methods

34. Seismic Method
• Introduction:
• Seismic techniques are commonly used to determine site
geology,
• stratigraphy, and rock quality. These techniques provide detailed
• information about subsurface layering and rock geomechanical
properties
• using seismic acoustical waves. Reflection and Refraction are the
most
• commonly used seismic techniques. These methods determine
geological
• structure and rock velocities by either refracting or reflecting
waves off
• boundaries between rock units with different seismic velocities

36. • Seismic Refraction:
• Seismic refraction investigates the subsurface by
generating arrival time and offset distance
information to determine the path and velocity of
the elastic disturbance in the ground.
• The disturbance is created by shot ,hammer ,
weight drop, or some other comparable method
for putting impulsive energy into the ground.
• Detectors measure the first arrival of the energy
and its time.
• The data are plotted in time – distance graphs
from which the velocities of the different layers,
and their depths can be calculated.

37. Seismic Reflection:
• Seismic Reflection follows the law of mirror
images – angle of reflection from a surface is
equal to the angle of incidence. Shots are fired, in
turn, at each of the geophone positions and
active geophones are progressively added ahead
of the shots.
• At each subsurface boundary, across . the elastic
and density parameters differ, a percentage of
the energy in the wave is reflected back to the
surface where it is recorded.

38. Gravity method:
• Measurements of the gravitational field at a series of
different locations over an area of interest.
The objective in exploration work is to associate
variations with differences in the distribution of
densities and hence rock type
• A gravimeter or gravitometer is an instrument used
in gravimetry for measuring the local gravitational
field of the Earth.

39. Magnetic Survey:
• An exploration method in which an instrument that measure
the intensity of the natural magnetic forces existing in the
earth’s subsurface is passed over the surface or through the
water.
• The instrument can detect deviations in magnetic forces, and
such deviations may indicate the existence of an underground
hydrocarbon reservoir.
• Magnetometer
An instrument used to measure the intensity and direction of
a magnetic field, especially that of the earth.