Deep-sea region of Gulf of Mannar

The Ministry of Petroleum and Natural Gas has recently issued a tender for hydrocarbon exploration as part of its 10th round of the Open Acreage Licensing Policy (OALP). This tender covers 25 offshore areas across India, totaling 1,91,986 square kilometers, with 9,990.96 square kilometers in the Gulf of Mannar area of southern Tamil Nadu being a key region.

What is Hydrocarbon Exploration?

• Hydrocarbon exploration is the process of searching for oil and gas reserves beneath the earth's surface, particularly in underwater areas (offshore).
• The government is inviting companies to submit bids for exploration rights, which would allow them to search for, extract, and produce oil and gas in these areas.
• Region:

• Tamil Nadu’s Gulf of Mannar region, which includes parts of Ramanathapuram and Thoothukudi districts, is believed to have potential oil and gas reserves.
• In addition to Tamil Nadu, the government has included four deep-sea blocks near the Andaman and Nicobar Islands. These areas were previously protected as "no-go zones".
• Concerns:
  • Blast sounds from surveys needed for mapping oil and gas reserves could disturb marine species.
  • Chemical waste from extraction could harm the fish population and other marine life, potentially leading to their migration or death.
  • Fishermen and local communities depend on the sea for their livelihoods, and they fear that this exploration could destroy their fishing grounds.

What Are Hydrocarbons?

• Hydrocarbons are organic compounds made up of Hydrogen and Carbon They form the basis of petroleum and natural gas.
• Kerogens are organic matter lumps that are the primary source of hydrocarbons found underground, formed from the remains of plants, animals, or marine ecosystems.
• Types of Hydrocarbons
• Alkanes (Saturated Hydrocarbons): Carbon atoms connected by single bonds.
  • Examples: Methane (CH4), Ethane (C2H6).
• Alkenes (Unsaturated with Double Bonds): At least one double bond between carbon atoms.
  • Examples: Ethylene (C2H4), Propylene (C3H6).
• Alkynes (Unsaturated with Triple Bonds): At least one triple bond between carbon atoms.
  • Examples: Acetylene (C2H2).
• Aromatic Hydrocarbons (Arenes): Rings of carbon atoms with alternating double bonds (aromatic rings).
  • Examples: Benzene (C6H6), Toluene (C7H8).

Formation and Storage of Hydrocarbons

• Hydrocarbons, including crude oil and natural gas, are found beneath sedimentary rocks.
• Formation Process:
  • Step 1: Dead plants and animals get buried under layers of mud, which eventually turn into rock.
  • Step 2: Over millions of years, heat and pressure break down the organic material (kerogen) into hydrocarbons.
  • Step 3: Crude oil and natural gas form and accumulate in rock layers, with oil being trapped below and natural gas floating above due to its lower density.

How Are Hydrocarbons Accessed and Extracted?

• Accessing Hydrocarbons:
  • Production Well Creation: The first step in extraction involves drilling a well through which hydrocarbons are brought to the surface.
  • Casing and Cementing: Steel casings are placed in the well to prevent cave-ins and protect against fluid intrusion.
  • Blowout Prevention: The pressure of drilling fluids must be controlled to avoid catastrophic eruptions of oil or gas.
  • Mud-Logging: The process of recording rock cuttings and analyzing their properties as the well is drilled.
• Extracting Hydrocarbons:
  • Primary Phase: Natural pressure from the reservoir pushes hydrocarbons to the surface.
  • Secondary Phase: Artificial pressure is applied to maintain the flow of hydrocarbons.
• Tertiary Phase: Enhanced recovery methods like steam injection are used to extract remaining hydrocarbons.