 Over the city 's history many large oil companies have been headquartered in the city , including Warren Petroleum ( which merged with Gulf Oil in what was then the largest merger in the energy industry ) , Skelly Oil , Getty Oil and <unk> . In addition , ConocoPhillips was headquartered in nearby Bartlesville . Industry consolidation and increased offshore drilling threatened Tulsa 's status as an oil capital , but new drilling techniques and the rise of natural gas has buoyed the growth of the city 's energy sector . 
