Petroleum is found in sedimentary rocks under pressure and heat. Exploration techniques include geological methods like subsurface mapping and remote sensing, and geophysical methods like gravity, electrical, magnetic, and seismic surveys to identify potential oil and gas deposits. Modern exploration uses hyperspectral remote sensing which provides high-resolution data to detect hydrocarbon indicators not visible to other sensors.
4. *The practice of locating or identifying the
area of available sources
of natural gas and petroleum is
called exploration.
*Hydrocarbon exploration is
the search by petroleum geologists
and geophysicists for deposits of
hydrocarbons, particularly petroleum and
natural gas, in the Earth
using petroleum geology.
Exploration:
5.
6. Petroleum etymologically means rock oil. It is a
natural organic compound mainly composed of HC
occurs either in gaseous or liquid state. The liquid part
obtained after the removal of dissolved gases
commonly referred as crude oil.
Many theories have suggested to explain the origin and
formation of petroleum/crude in nature.
They were listed as:
*Carbide theory
*Engler ’s theory
*Modern theory
7. Theories of petroleum:
Carbide or inorganic theory: Petroleum is produced
inside the earth by the action of water on metallic
carbides.First lower HC were produced and by
hydrogenation and polymerization higher HC were
produced.
• ENGLER’S Theory: (animal origin) It is produced by
the decomposition of marine animals
under high
pressure and temperature.
• Modern theory: (Vegetable origin) It is from biogenic
origin, they are produced by a mother substance
kerogen or shales.
8. OIL FORMATION:
Accumulation of organic material and its
environmental conditions and good heating
event and trapping mechanism
give the capability of oil formation.
Three components were
needed for oil formation:
*Source rock
*Reservoir rock
*Cap rock
And mainly kerogens are present in cap rocks
(limestone, sandstone, shales) and so they are
found in sedimentary rocks.
9. COMPOSITION AND TYPES OF
CRUDE:
O They contain HC and Non-HC compounds:
*HC compounds includes paraffins, napthenes,
aromatics, asphaltics, olefins.
*Non- HC includes sulphur, nitrogen, oxygen, and
some other metals.
O Crudes are grouped into:
(i) Paraffinic base
(ii) Hybrid or naphthenic base
(iii) Asphaltic base
(iv) Intermediate base.
10. • Petroleum is a mixture of various hydrocarbons
and varies in colors from light brown to dark brown
or black.
• Its products were classified on three basis:
light, middle and heavy distillates.
• LIGHT DISTILLATES: LPG (natural gas, associated
and dissolved gas), Naphthas, Gasoline (petrol or
motor sprit).
• MIDDLE DISTILLATS: Kerosene, Diesel,
ATF(Aviation Turbine Fuel), fuel oils, lube oils.
• HEAVY DISTILLATES or RESIDUES: Petroleum
wax, Bitumen, Petroleum coke.
11. 1. Geological methods:
*Remote sensing
*Subsurface mapping
2.Geophysical techniques:
*Gravity : Respond to density
*Electrical : Respond to resistivity
*Magnetic : Respond to susceptibility
*Seismic : Respond to velocity
3. Geochemical techniques:
*Direct method
*Indirect method
Exploration techniques:
12. The hunt for the HC is focused at the favorable or
promising areas based on geological consideration.
1.Geological Methods:
Sub surface mapping:
Selection and mapping of promising areas which
satisfy the criteria of promising areas which satisfy the
criteria of being sedimentary rocks of marine origin with
the presence of anticline structure of Mesozoic,
Cenozoic and Paleozoic periods. They are expressed
in terms of known geographic locations,
stratigraphic markers, and rock composition at the
depth. It is given by GIS (Geographic Information
system)technology.
*Contour maps are widely used in this type.*
13. • Remote sensing: The scanning of the earth by
satellite or high-flying aircraft in order to obtain
information about it. Remote-sensing data are
highly useful for
the oil and gas industry. Remote sensing has
proven to be an integral tool for downstream
and upstream oil and gas operations through
evaluation of infrastructure for well-site
planning and for exploration through large-
scale regional reconnaissance. Spectral
analysis is a key form of processing to evaluate
for surface outcrops and surface hydrocarbon.
• Benefits:
14.
Gravimetric survey: It is done by gravimeter. It
measures the gravitational field and this reading
correlates with the density of the region. It measures
gravity in the units of acceleration called Milligan. It
provides the information regarding underlying
formation of oil, salt domes, basin shape and
sedimentary thickness.
Electrical Survey: The accuracy is mainly
dependent on geological conditions. It is suitable for
wells drilled with fresh mud.
Types :
*Electrical resistivity topography (ERT)
* Self Potential method (SP)
* Induced polarization (IP)
2. Geophysical techniques:
15. * Magnetic survey: It is done by air-borne
magnetometer either in ground or air. Principle
:magnetic attraction on the surface depends on the
magnetic intensities of the rocks and their distance
from the surface.
Aim: To locate the sedimentary rocks. They have
low magnetic properties than the other rocks.
*Seismic survey: It is conducted by sound
waves. It indicates the nature of the rock and angle
of dip. It is used in onshore to detect the echoes
returning from the ground sent to sea by
geophones and hydrophones.
16.
17. 3. Geochemical techniques:
• Direct method:
It involves the presence of dispersed oil
components in the form of HC or bitumen in the
soils, waters and rocks in the vicinity of oil and gas
accumulations.
Types: * Gas logging
* Bitumen survey
* Hydro chemical techniques
18. • Indirect method:
It is based on the detection of any chemical,
physical or microbiological changes in the soils,
waters, or rocks associated with the oil and gas
deposits.
Types:
* Soil-salt method
* Oxidation and reduction potential
method
* Microbiological method
* Hydro chemical technique
20. Modern method: hydro spectral Remote sensing.
This method gaining information by the use of
sensors.
The resolving power of sensor is high.
It has good radiometric resolution and thus
preferred more than multi spectral remote
sensing.
Hyper spectral imaging samples a wide variety of
bandwidths in the light spectrum to provide a
rich dataset and detect objects of interest not
visible to single-bandwidth imaging sensors.
21. Spectral remote sensing involves the collection,
processing and interpretation of electromagnetic
energy that is reflected or emitted from features
on the Earth's surface.
The main difference between
multispectral and hyper spectral is the number of
bands and how narrow the bands
are. Multispectral imagery generally refers to 3 to
10 bands. A hyper spectral image could have
hundreds or thousands of bands.
HYSIS (Hyper spectral Imaging Satellite) is an
Earth observation satellite which will
provide hyper spectral imaging services to India
for a range of applications in agriculture, forestry
and in the assessment of geography such as
coastal zones and inland waterways
22. Petroleum is found in sedimentary rocks
under high pressure but at low temperatures.
If the hydrocarbon index (HI) is lesser than 0
the oil is present if HI>0 then no oil is
present.
Long chain HC are bitumen & Short chain HC
are gas & medium chain HC are paraffin.
Age of oil is indicated by CPI (Carbon
Preference Index)
