The amount of oil being extracted is mostly driven by demand, not supply. Not entirely. After all extra supply means lower prices and therefore increased deman

The amount of oil being extracted is mostly driven by demand, not supply. Not entirely. After all extra supply means lower prices and therefore increased demand. But demand is fairly inelastic - that's why prices can change so rapidly and consumption remains fairly steady. Therefore the choice of extraction technology makes little difference to how much oil we get. It just affects which marginal wells are worthwhile, and the likelihood of other kinds of environmental damage. Therefore if you inject biofuel instead of water, you really have altered the net result. Not enough to encourage extracting fuel just to store biofuel, but enough to be better than a kick in the teeth. Ideally we'll get to injecting fuel into stopped wells and start undoing damage. And in the meantime, current efforts mean that we'll have the technology when that point comes. And so this activity is on a path towards what we want. (There are similar arguments for natural gas. Natural gas is a natural complement to highly variable renewable energy. So you want to add renewables, add natural gas plans, and use the natural gas to balance the grid. In the long run you replace natural gas with storage such as batteries. But in the short term, natural gas is on a path towards a sustainable future.)