An oil depletion allowance is based on the theory that with every year oil is pumped out of a well, there is less oil that can be pumped, and so you should get a deduction for this. The fact is that there is no way to know how much oil can be pumped out of a given well, because oil flows from a distance into the pumping area, and no one knows how much is there or how much you can pump. There are wells in Texas that have been producing for forty years. They can inject water , steam or chemicals or fracking fluids and revive old wells AFTER they have claimed an oil depletion allowance.
If a depletion allowance is bogus and nort allowed for the big producers, why does it make sense for the smaller ones?
Suppose we apply the same principle to income tax, since every year that you live, you have one year less of lifespan, and therefore the government owes you some sort of credit for that. It is a bogus horseshit idea thought up back in the 1930's or earlier. Oil is a gamble, like your life or mining is a gamble. You don't like it, then do not mine ore and do not pump oil.
And we will never get a life depletion allowance.