Having a minority stake in anything means you have to accept that you have little control of income, expense or reinvestment decisions. Fine if you are one small investor amongst millions, but a different thing if it is a 75:25 ownership. It may also be very difficult to sell on your stake if you want out or need the money.
At current oil prices, profit (if any) on small oil wells will be at its lowest, so perhaps good time to invest, but it could drain a lot of cash before you see any return to profitability. And meanwhile you have no control over how much extra you might need to put in to cover operating costs.
Too risky for me! But feel free to post back here in ten years to show how good a risk it was!