Cairn's Ravva oil exploration block in Krishna Godavari Basin off the Andhra Pradesh Coast is the place that has made the Edinborough-based Cairn Energy one of the most successful oil exploration companies in the world. They make Cairn's to-be listed Indian subsidiary Cairn Energy India, the heart of Cairn's global operations. Something that's never happened to a global company since the East India Company 300 years ago.