回帖：Professor Li,
Thanks for inviting me into this forum. As I mentioned in my PM, I will give it a try but can't promise anything else.
I did not participate in the discussion when you posted the same subject In http://forum.petro-china.com/. I restricted joining the discussion because I know, in real world, gas moving down the oil zone could happen.
Let me lay out the following scenario. a layer of oil separated by shale sitting on top of a layer of gas. The oil zone is higly under-saturated. When the layers were deformed by salt movement,The oil & gas become connected at the base of saltcanopy. The gas, which has higher pressure than oil, inlow into the oil zone (like a gas injector.), we ran into this problem in the field I'm working in GoM, The GOR is increasing even the oil rate is constant. The down dip well has higher GOR than the updip well. The presence of gas at the apex of the oil zone is also confirmed by logs and MDTs.Is this 油气倒灌, I can't say because I'm still confused about the definition of 油气倒灌. Can the gas coning down the oil zone, from past N2 and CO2 project,Yes, it has been reported and discussed.