26 USC 193 - Tertiary injectants

(a) Allowance of deduction 
There shall be allowed as a deduction for the taxable year an amount equal to the qualified tertiary injectant expenses of the taxpayer for tertiary injectants injected during such taxable year.
(b) Qualified tertiary injectant expenses 
For purposes of this section
(1) In general 
The term qualified tertiary injectant expenses means any cost paid or incurred (whether or not chargeable to capital account) for any tertiary injectant (other than a hydrocarbon injectant which is recoverable) which is used as a part of a tertiary recovery method.
(2) Hydrocarbon injectant 
The term hydrocarbon injectant includes natural gas, crude oil, and any other injectant which is comprised of more than an insignificant amount of natural gas or crude oil. The term does not include any tertiary injectant which is hydrocarbon-based, or a hydrocarbon-derivative, and which is comprised of no more than an insignificant amount of natural gas or crude oil. For purposes of this paragraph, that portion of a hydrocarbon injectant which is not a hydrocarbon shall not be treated as a hydrocarbon injectant.
(3) Tertiary recovery method 
The term tertiary recovery method means
(A) any method which is described in subparagraphs (1) through (9) of section 212.78(c) of the June 1979 energy regulations (as defined by section 4996 (b)(8)(C) as in effect before its repeal), or
(B) any other method to provide tertiary enhanced recovery which is approved by the Secretary for purposes of this section.
(c) Application with other deductions 
No deduction shall be allowed under subsection (a) with respect to any expenditure
(1) with respect to which the taxpayer has made an election under section 263 (c), or
(2) with respect to which a deduction is allowed or allowable to the taxpayer under any other provision of this chapter.