The underground crude oil storage caverns of Visakhapatnam, India

Underground storage schemes are gaining importance in India, as all over the world. Such storage schemes involve the excavation of large underground caverns, connecting tunnels and various types of shafts. This example provides storage for more than 1.3 mill. metric tons of crude oil stored in unlined caverns 20 m wide, 30 m high and up to 820 m long. The scheme also includes three 110 m deep product intake shafts, two 90 m deep product extraction shafts and about 2,600 m of tunnels. The total volume, excavated by drill and blast method, is about 2 mill. m3 and rock support is provided by post-grouted rock bolts and steel fibre reinforced shotcrete. The product is confined on the principle of a groundwater curtain system, essentially employing ground water pressure gradients to contain the crude oil within the unlined rock cavern complex. Excavation works on the project commenced in the middle of 2008 and, after some delays, were finally completed in February 2014. This paper focuses on the risk management practices employed for this project. The paper “Rock mass behaviour of weathered, jointed and faulted Khondalite - Examples from the underground crude oil storage caverns, Visakhapatnam, India” by Sigl, Millen and Höfer-Öllinger that refers to the actual situation will be published in issue 3-2014 of Geomechanics and Tunnelling.