Indiana Code Title 6. Taxation § 6-1.1-4-12.4

Sec. 12.4. (a) For purposes of this section, the term “oil or gas interest” includes but is not limited to:

in any oil or gas located on or beneath the surface of land which lies within this state.

(b) Oil or gas interest is subject to assessment and taxation as real property.  Notwithstanding section 4.2 of this chapter, each oil or gas interest shall be assessed annually by the assessor of the township in which the oil or gas is located, or the county assessor if there is no township assessor for the township.  The township or county assessor shall assess the oil or gas interest to the person who owns or operates the interest.

(c) A piece of equipment is an appurtenance to land if it is incident to and necessary for the production of oil and gas from the land covered by the oil or gas interest.  This equipment includes but is not limited to wells, pumping units, lines, treaters, separators, tanks, and secondary recovery facilities.  These appurtenances are subject to assessment as real property.  Notwithstanding section 4.2 of this chapter, each of these appurtenances shall be assessed annually by the assessor of the township in which the appurtenance is located, or the county assessor if there is no township assessor for the township.  The township or county assessor shall assess the appurtenance to the person who owns or operates the working interest in the oil or gas interest.