Visakhapatnam: While reasons like corrosion and use of substandard material are being given for the gas pipeline leak, which led to the blast that killed 15 persons in East Godavari, experts are also pointing at the possibility of land subsidence as one of the possible reasons for the leak.
Retired professor of Andhra University’s geology department Dr G. Krishna Rao, who has undertaken many studies on the Krishna-Godavari Basin and other sites of gas exploration near Kakinada, observed that about 60 per cent of gas pipeline failures were due to excavations in the vicinity, while 20 per cent were accounted for by corrosion problems.
“In the K-G Basin, often there is land subsidence or sinking of land. As a result of this subsidence, the pipeline, which was laid about 20 to 25 years ago, loses its base. In such places, the ground below the pipeline has to be grouted with soil or elevated with supports to restore the horizontal alignment of the pipeline. There are also reports of pipeline breakages due to land subsidence in some countries,” he added.
Prof. Rao further observed that while attending to causes like mechanical problems in pipeline fittings, quality of pipes and corrosion, land stability and subsidence should also be thoroughly investigated by surveying the land for elevation changes. He added that areas prone to pipeline failures should be identified and remedial measures should be taken where necessary to avoid future pipeline breakages.
Land subsidence is a major problem in the production of natural gas from semi-consolidated sandstone reservoir rocks. This parameter has been ignored during earlier production activities in the K-G Basin, he added.
An environmental impact assessment report submitted by ONGC on expansion of the Odalarevu Onshore Terminal in East Godavari district last year, had quoted from a report submitted in October 2009 by a sub-committee constituted by the MOEF on the direction of the High Court to look into land subsidence.
The sub-committee had recommended that oil and gas extraction had led to land subsidence in many parts of the world and therefore this factor should be taken into consideration while taking up any project. The committee had also suggested getting the K-G Basin investigated by an expert central institute for existing or likely land subsidence in the region. It seems this suggestion has not been complied with, Prof. Rao said....
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