Why is India drilling a 6-km deep hole in Maharashtra?

Sub: Geography

Sec: Geomorphology

Context:

The Borehole Geophysics Research Laboratory (BGRL) in Karad, Maharashtra, a specialized institute under the Ministry of Earth Sciences of the Government of India is mandated to execute India’s sole scientific deep-drilling programme at Koyna, Maharashtra.

More on news:

Powerful earthquakes measuring more than 7.5 on the Richter scale occur at the boundaries of tectonic plates and are almost certainly associated with a severe loss of infrastructure and life.
However minor earthquakes that occur in a plate’s interior are more challenging to predict because they occur at the least expected sites and could strike densely populated habitats.
Therefore scientific deep drilling becomes an indispensable tool for progress in the earth sciences.
Countries like the U.S., Russia, and Germany conducted such scientific projects in the 1990s.
Similarly India aims is to drill the earth’s crust to a depth of 6 km and conduct scientific observations and analysis to help expand the understanding of reservoir-triggered earthquakes in the active fault zone in the Koyna-Warna region of Maharashtra.

What is scientific deep-drilling?

Scientific deep-drilling is the enterprise of strategically digging boreholes to observe and analyze deeper parts of the earth’s crust.
It offers opportunities and access to study earthquakes and expands our understanding of the planet’s history, rock types, energy resources, life forms, climate change patterns, the evolution of life, and more.
Such missions can be a hub of direct, in-situ experiments and observations and strategically monitor a region’s fault lines and earthquake behavior (including nucleation, rupture, and arrest).

What is the drilling technique used at Koyna?

The Koyna pilot borehole is about 0.45 m wide (at the surface) and roughly 3 km deep.
It is unique in many ways because of the drilling technique: a hybrid of two well-established techniques called mud rotary drilling and percussion drilling (a.k.a. air hammering).
The rotary drilling technique uses a rotating drilling rod made of steel, attached to a diamond-embedded drill bit at the bottom.
The second technique, air hammering, pushes highly compressed air (in place of the drilling mud) through the drilling rod to deepen the borehole and flush the cuttings out.

What are the challenges of scientific deep-drilling?

Scientific deep-drilling is also the most challenging method as deep-drilling is labor- and capital-intensive.
The earth’s interior is also a hot, dark, high-pressure region that hinders long and continuous operations.