The largest oil and gas corporation in India by market capitalization, production volume, and overall revenue scale is Reliance Industries Limited (RIL), which operates the massive Jamnagar Refinery complex as the largest and most complex refining hub in the world. In the public sector, Oil and Natural Gas Corporation (ONGC) stands as the premier state-owned crude oil and natural gas exploration and production giant, contributing significantly to domestic energy security and petroleum output across the nation.