Underground crude oil storage projects in India / Unterirdische Rohölkavernen in Indien

Indian Strategic Petroleum Reserves Limited has awarded the packages of constructing underground unlined rock caverns for storage of 1.33 and 1.25 MMT of high sulphur crude oil at Visakhapatnam (Andhra Pradesh) and Padur (Karnataka) respectively to Hindustan Construction Company Limited, where-in Geoconsult is engaged for detailed design and site services.

The unlined rock caverns for oil and gas storage call for site characterization in terms of geology, hydro-geology, geochemistry, geomechanics and geotechnics, which in turn facilitates assimilation, assessment and amalgamation of all relevant data to establish an overall geological and/or geotechnical framework for the projects. In general, the construction of an underground unlined rock cavern compriseds five principal activities: (i) geological and/or geotechnical site investigations; (ii) stability assessment; (iii) temporary rock supports design; (iv) excavation and related works; and (v) permanent rock supports re-design according to the observational approach.

This paper outlines (a) the construction stage geological and/or geotechnical investigations to acquire geological/geotechnical data for rock mass quality appraisal as per Q-system and permanent rock support recommendations, (b) design criterion to utilize the rock itself as the principal structural material, to create as little disturbance as possible during the construction stage, and to add only the required supports, and (c) geotechnical instrumentation and monitoring to measure displacements at the surface and within the rock mass in order to fine-tune the excavation methods and rock supports, undertaken during construction stage of the project.