HYDROCARBON EXTRACTION -
GEOGRAPHY
News: How are hydrocarbons extracted
from under the ground? | Explained
What's in the news?
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Over millennia, mighty geological processes in the
earth’s crust heated and compressed together pieces of life-forms that had been
dead for a while.
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Eventually, this mulch of organic matter
accumulated as hydrocarbons inside rock formations.
Hydrocarbon:
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A hydrocarbon is an organic compound made solely of carbon and hydrogen atoms.
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These naturally occurring substances are the
foundational elements of crucial energy resources such as crude oil, natural gas, coal, and others.
Location:
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Hydrocarbons are primarily located in subterranean rock formations.
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Hydrocarbons are also found in plants, animals, and their fossils.
Forms:
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They exist in various forms such as natural gas,
coal, crude oil, and petroleum.
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These hydrocarbons accumulate in reservoirs
underground when a more resistant rock type overlays a less resistant one,
creating a lid that causes hydrocarbons to accumulate below it.
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The primary source of hydrocarbons in this rocky underground is called kerogen, which are lumps of organic
matter.
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The type of kerogen determines the type of
hydrocarbon that is produced.
Extraction of
Hydrocarbons:
1. Location
Determination:
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Petroleum geologists evaluate rock porosity and
permeability to locate hydrocarbon reservoirs.
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They identify source rocks rich in kerogen, the main hydrocarbon source, and use
data-driven modeling and exploratory drilling to estimate hydrocarbon volumes.
2. Drilling:
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Drilling and reservoir engineers aim to maximize
extraction without harming the reservoir.
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They drill a production well, the main channel
through which hydrocarbons are brought to the surface.
3. Preparation:
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The plant material is prepared by grinding or
breaking it down into smaller pieces for increased surface area.
4. Extraction:
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The prepared material is placed in the extraction
vessel, and the hydrocarbon solvent is passed over it to dissolve the desired
compounds.
Go back to basics:
Kerogen:
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Kerogen is the portion of naturally occurring organic matter that is non-extractable using
organic solvents i.e. it is insoluble in
solvents.
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Kerogen represents about 90% of the organic carbon in sediments.
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It occurs in source
rock and may expel hydrocarbons upon thermal cracking.
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Typical organic constituents of kerogen are algae
and woody plant material.
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It consists of lighter as well as heavier
hydrocarbons and acts like a precursor of oil and natural gas.
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Kerogens have a high molecular weight relative to
bitumen, or soluble organic matter. Bitumen forms from kerogen during petroleum
generation.
Types of Kerogens:
Type I:
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It consists of mainly algal and amorphous (but presumably algal) kerogen and highly
likely to generate oil.
Type II:
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It consists of mixed
terrestrial and marine source material that can generate waxy oil.
Type III:
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It consists of woody
terrestrial source material that typically generates gas.
Uniqueness of Kerogens:
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The types of kerogens present in a rock largely
control the type of hydrocarbons generated in that rock.
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Different types of kerogens contain different
amounts of hydrogen relative to carbon and oxygen.
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The hydrogen content of kerogen is the controlling
factor for oil vs. gas yields from the primary hydrocarbon-generating
reactions.
Sedimentary Basins in
India:
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India boasts 26
sedimentary basins spanning 3.4 million square kilometres.
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These basins are distributed as follows.
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49% on land
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12% in shallow water
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39% in deepwater regions.
Types:
They are categorised based on hydrocarbon resource maturity such as
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Category-I: Active basins with existing reserves and ongoing
production.
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Category-II: Basins with potential reserves awaiting commercial
development.
● Category-III: Basins with unexplored resources yet to be discovered.