I usually refuse this dilemma which I noticed only impacted opinions. On this end, this makes sense, you’ve denied an opportunity, but not stopped anything that was already happening. Therefore people have opinions, but otherwise there is no change.
Today I went the other way. It came up in early game, my economy was in the tank, so I approved the oil development. It affected opinions, and oil supply, but not GDP or unemployment. The argument in favor of oil developments is always about the economy and the jobs, which it would create. I would suggest that this approving the oil project should create a 1% boost to GDP and dip in unemployment, which would eventually fade over time. Similar results already occur in other dilemmas, so it’s not unreasonable to add them here.