JNTU B.Tech IV NATURAL GAS HYDRATES AND COAL BED METHANE Previous Question Paper (July/August - 2022 - R18)

Natural gas is primarily sourced from conventional reservoirs, often found in association with petroleum deposits, or from unconventional sources such as shale gas, tight gas, and coal bed methane. It is formed through the thermogenic decomposition of organic matter under high pressure and temperature over geological time, or through biogenic processes in shallow sediments.

The primary uses of natural gas include: 1) Power generation in gas-fired turbines and combined-cycle plants; 2) Industrial applications as a fuel for heating, steam production, and as a feedstock for petrochemical manufacturing (e.g., ammonia and methanol production); 3) Residential and commercial heating and cooking; and 4) Transportation as Compressed Natural Gas (CNG) or Liquefied Natural Gas (LNG).

Water molecules are the fundamental building blocks of gas hydrates, serving as the host framework. Through hydrogen bonding, water molecules arrange themselves into a rigid, three-dimensional crystalline lattice structure known as a clathrate. This lattice creates internal cavities or cages of specific sizes.

The importance of these molecules lies in their ability to trap guest gas molecules (such as methane, ethane, or propane) within these cages without forming chemical bonds. The stability of the hydrate is entirely dependent on the physical presence of the guest molecules, which provide the necessary van der Waals forces to support the water lattice against collapse. Without the structured water framework, the gas molecules would remain in a gaseous or dissolved state.