Introduction

Oil reserves are formed in sedimentary basins where organic matter is trapped and transformed over geological time. Offshore oil reserves, found beneath continental shelves and oceanic basins, have emerged as key resources shaping the geography of global energy distribution.

Body

Geographical Explanation for the Distribution of Offshore Oil Reserves

• Continental Shelves: Broad and shallow shelves favour thick deposition of marine sediments rich in organic matter, which, under pressure convert into hydrocarbons.
  • Eg: Persian Gulf, Mumbai High.
• Passive Continental Margins: These margins experience slow subsidence and continuous sediment accumulation, creating ideal conditions for hydrocarbon generation.
  • Eg: Brazil’s Atlantic coast, West Africa (Nigeria, Angola).
• Rifted Basins and Fault Zones: Submerged rift valleys and grabens act as structural traps that preserve petroleum deposits beneath the sea floor.
  • Eg: North Sea basins of UK and Norway.
• Deltaic and Coastal Sedimentation: River deltas carry organic-rich sediments into the ocean, forming prolific offshore basins with large reserves.
  • Eg: Niger Delta, Krishna–Godavari Basin (India).
• Sedimentary Troughs and Depressions: Thick layers of porous rocks overlain by impervious cap rocks in troughs trap oil effectively in offshore settings.
  • Eg: Campos Basin (Brazil), South China Sea.

Difference between Onshore and Offshore Oil Reserves

Conclusion

The distribution of offshore oil reserves underlines geography’s role in global energy supply. While these reserves are crucial for energy security, their exploitation must be balanced with ecological safeguards and a gradual shift towards offshore wind and other renewables for a sustainable energy future.

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