Hydrocarbon is an organic chemical compound, compised of hydrogen and carbon atoms. It was a naturally occurring compound. It forms the basis of crude oil, natural gas and coal. My presentation incorporates about formation of Hydro carbon.

1. SUBSURFACE OIL AND GAS
ACCUMULATION
Under the guidance of
K.V NAGESH sir
GM(P)
HPHT Asset, ONGC
Presented by,
B.AKHIL
T.SATYA SWAROOP
P.JOSHNA

2. Formation of
HYDRO
CARBON
• Plants and animals were died
and buried on the ocean floor.
• Over the time the plants and
animals were covered by slit and
sand.

3. STEP 1: DIAGENESIS FROM
KEROGEN
• When organic sediments are deposited
they are saturated with water and rich in
minerals.
• Through chemical reaction , microbial
action and compaction under mild
conditions of temperature and pressure the
organic molecules change into a waxy
material known as Kerogen and a black
tar like substance called Bitumen.
• All this occurs within first several
hundred meters of burial.

4. STEP 2: CATAGENESIS TURNS KEROGEN INTO LIQUID AND
GASEOUS HYDROCARBONS
• The deeper the burial, the process of
catagenesis begins where temperature
and pressure increases the hydro carbon
chains are formed by thermal
degradation of kerogen.
• The conditions of catagenesis determine
the product, such that higher
temperature and pressure lead to more
complete “cracking” of the kerogen and
progressively lighter and smaller
hydrocarbons.

5. STEP 3: METAGENESIS
• The last stage of maturation and
conversion of organic matter to
hydrocarbons.
• Metagenesis occurs at temperatures of
150 to 200 °C.

6. Vitrinite Reflectance
with respect to
depth during the
process of
maturation of
KEROGEN

7. HYDROCARBON
MIGRATION
• There are the movements of
fluids in the subsurface.
• The rocks containing oil and gas
alternate in the earth's crust with
the rocks that do not contain
hydrocarbon.
• There are three main types of
migration: primary , secondary
and tertiary migration.

8. 1. PRIMARY MIGRATION
• The expulsion of petroleum from a source rock into adjacent rocks.
• The hydrocarbons migrate through dense, impermeable source rocks with
low porosity into neighboring rocks being permeable carrier beds
 SOURCE ROCK
• It is an organic matter rich which can gradually generate oil and gas.
• It was formed during diagenesis.
• When the temperature exceeds the oil generation temperature in
the source rock catagenetic alterations of the crude oil compositions are
caused.
• Source rocks are fine grained sedimentary rocks of low permeability.

9. 2. SECONDARY MIGRATION
• The subsequent flow of hydrocarbons within these porous and more
permeable rock units.
• The driving mechanism for secondary migration are buoyancy, capillary
pressure.
 RESERVOIR ROCK
• It is a subsurface body of rocks with sufficient porosity and permeability
to stone and transmit fluids.
• They are formed also in under temperature and pressure in which
hydrocarbon can be preserved.

10. 3. TERTIARY MIGRATION
• It occurs when petroleum moves from one trap to another or to a seep.
 CAP ROCK
• To form oil and gas accumulation their migration paths must have been
stopped by a roof i.e, caprock (seal).
• It is an impermeable rock that acts as a barrier to further migration of
hydrocarbons.

11. References:
Hydrocarbon exploration and production , 2nd edition(2008)
Frank Jahn, Mark Cook and Mark Graham.
Geology and Geochemistry of oil and gas (2005)
G.V. Chilingar, L.A. Buryakovsky, N.A. Eremenko & M.V. Gorfunkel
Exploring for Oil and Gas Traps (1999)
Magoon,N. H. Foster
https://personal.ems.psu.edu/~pisupati/ACSOutreach/Petroleum_2.html

12. Whoever controls oil controls much
more than oil.
-JOHN MACAIN.