- The Borehole Geophysics Research Laboratory (BGRL) in Karad, Maharashtra, under the Ministry of Earth Sciences, leads India’s deep-drilling program.
- BGRL is a specialised institute mandated to execute India’s scientific deep-drilling programme.
- The aim is to drill to a depth of 6 km to study reservoir-triggered earthquakes in the Koyna-Warna region, which has experienced frequent earthquakes since the impoundment of the Koyna Dam in 1962.
The Koyna borehole
- It uses a hybrid of mud rotary drilling and air hammering, with the technique chosen based on rock type and drilling conditions.
- Mud rotary drilling uses a diamond-embedded drill bit cooled and lubricated by drilling mud, which also removes rock cuttings.
- Air hammering uses compressed air to deepen the borehole and flush out cuttings.
- These methods enable the collection of core samples and rock chips for detailed study.
- A 3-km deep pilot borehole in Koyna is complete, and the Ministry plans to extend it to 6 km.
- Scientists currently lack the means to predict the exact timing and location of earthquakes.
- Major earthquakes, measuring over 7.5 on the Richter scale at tectonic plate boundaries, are associated with severe infrastructure damage and loss of life, and can trigger tsunamis.
- However, smaller earthquakes occurring within tectonic plates are harder to predict and can impact densely populated areas unexpectedly.
- The anticipated temperature at 6 km depth will inform the design of drilling equipment and sensors.
- Ongoing research on the Koyna samples by over 20 groups nationwide includes studies on rock frictional properties and microbial life in extreme environments.
- International researchers are also interested in these samples for projects like carbon capture and storage.
Scientific Finding
- The pilot borehole revealed significant geological information, including 65-million-year-old Deccan trap lava flows and 2,500-2,700-million-year-old granitic basement rocks.
- Downhole measurements provided new data on rock properties, fluid and gas compositions, temperature, stress regimes, and fracture orientations.
- High-resolution images of the borehole wall and hydraulic fracturing experiments offered insights into the stress regimes and fault properties.
Dig Deeper: Read about the Kola Superdeep Borehole.
