gordo: The Investment need to develop a Gas elephant like KG is extremeley large. On the other hand development of Tarapore which is sweet oil field requires less capital and is easy.
Normally for a well established oil field we need one PP per section and may be some fracturing from time to time. For a deep gas field we may need uto 20 PPs per section. The cost is enormous if you want very high recovery in a deep complex gas field.