The recent exploration of the Krishna-Godavari (KG) Basin by researchers from the Agharkar Research Institute (ARI) has generated significant findings about biogenic methane hydrate. The ARI, an independent institution under the Department of Science and Technology in India, launched this study to investigate the living organisms responsible for creating biogenic methane.
Understanding Biogenic Methane
Biogenic methane is formed by the metabolic activities of living organisms. Particularly, microorganisms called methanogens are the key players behind the production. Methanogens operate in hypoxic conditions, where oxygen levels are low, and produce methane as a by-product of their metabolism. The research team has identified that methane hydrate, a significant potential energy source, is mainly produced by Methanosarcina, followed by other genera like Methanoculleus and Methanobacterium in the KG Basin.
Formation and Properties of Methane Hydrate
Methane hydrate is a crystalline solid composed of a methane molecule surrounded by a cage of interlocking water molecules. This “ice” only forms naturally in subsurface deposits under suitable temperature and pressure conditions, such as in oceans.
However, methane hydrate poses challenges in terms of handling and study. If removed from its natural temperature/pressure environment, it becomes unstable. Hence, unlike other subsurface materials, methane hydrate deposits cannot be drilled or cored without causing melting and gas escape. For these reasons, it carries various names including methane clathrate, hydromethane, methane ice, fire ice, natural gas hydrate, and gas hydrate. Other hydrocarbon hydrates, such as propane hydrate and ethane hydrate, are also commonly found in methane hydrate deposits.
Significance of the Study
Methane is viewed as a clean and economic fuel. It’s estimated that one cubic meter of methane hydrate holds 160-180 cubic meters of methane. The diversity of methanogens in the KG basin is considerably rich, which suggests that the basin is a significant source of biogenic methane, more so than the Andaman and Mahanadi basins. Furthermore, even the lowest estimates indicate that the methane in the hydrates in the KG Basin exceeds twice the total fossil fuel reserves globally.
About Krishna-Godavari Basin
The Krishna-Godavari Basin is a vast deltaic plain formed by the Krishna and Godavari rivers in the state of Andhra Pradesh, India. The land part of this basin covers an area of 15,000 sq. km, while the offshore part extends across an area of 25,000 sq. km up to 1000 m isobath.
The basin contains about 5 km thick sediments with multiple cycles of deposition, ranging from Late Carboniferous to Pleistocene periods. Its major geomorphological units include upland plains, coastal plains, recent flood and delta plains. It houses the D-6 block that contains significant natural gas reserves in India. The first gas discovery in the basin was made by ONGC in 1983. The basin is also known as a habitat for the Olive Ridley Sea Turtle, an IUCN Vulnerable species.