What does this mean: "repeals the tax deduction for tertiary injectant expenses" ? If I'm an oil driller and I spend $25 on "tertiary injectants" to produce $2

What does this mean: "repeals the tax deduction for tertiary injectant expenses" ? If I'm an oil driller and I spend $25 on "tertiary injectants" to produce $200 of oil, my real income is $175. So, the government should only be taxing me on $175. Does this deduction mean simply that? Or is it an extra bonus deduction allowing me to claim $200 - $25 - $25 bonus = $150 income? If it's just a normal allowed expense, then why is the government even involved in deciding which of my expenses are legit (beyond fraud levels)? If it's a bonus expense that counts twice, then why was this even passed in the first place? Politics aside, I'm getting a strong "chesterton's fence" feeling here - we're removing something that sounds like it shouldn't exist in either scenario, without understanding what led it to exist in the first place...