Rajahmundry: Soil erosion from islands on Godavari river is attributed to land subsidence due to aggressive exploration and extraction of natural gas and oil, both in onshore and offshore projects.
Experts say that over a period of time, land level in islands has sunk by three to five feet and this is resulting in river water entering the islands and submerging crops. At times, even habitations get submerged as the river gets flooded.
Experts say land subsidence is also witnessed in coastal villages like Antarvedi, Bendamuru Lanka and Yanam, resulting in a surge of sea water towards land by about 600 metres. They blame the firms involved in exploration and exploitation of natural gas at onshore projects for this. These firms fail to fill up wells with carbon dioxide, in areas where the gas is extracted. This is the prevailing practice in countries using advanced technology for extraction of natural gas.
Once the natural gas gets extracted from the reservoir located down below the earth at a depth of a few thousand metres, a vacuum will be developed. This needs to be filled with carbon dioxide. If the vacuum is not filled, it may result in subsidence of surface land. No scientific study has been done on land subsidence especially in KG basin so far.
Public sector oil major ONGC which is having as many as 150 active wells and produces 19 lakh cubic metres of natural gas and 750 tonnes of oil per day denies there is land subsidence due to extraction of oil and gas.
Andhra University retired professor Krishna Rao said, “It is time the firms extracting a huge quantum of oil and gas especially in KG basin s adopted advanced technology to avoid land subsidence. This is resulting in soil erosion on islands and sea water surge in coastal areas, as also salinity of ground water, due to ingress of sea water to the mainland.”
