(a) In this subchapter, "common purchaser" means:
(1) every person that purchases crude oil or petroleum produced within the limits of this state and that is affiliated through stock ownership, common control, contract, or in any other manner with a common carrier by pipeline or is itself a common carrier;
(2) every person, gas pipeline company, or gas purchaser that claims or exercises the right to carry or transport natural gas by pipeline or pipelines for hire, compensation, or otherwise within the limits of this state or that engages in the business of purchasing or taking natural gas, residue gas, or casinghead gas thereof;
(3) every person that operates a crude oil gathering system, whether by pipeline or truck, that may purchase crude oil or petroleum in this state, whether or not it is a common carrier or affiliated with a common carrier; and
(4) the business of purchasing or of purchasing and selling crude petroleum by the use of a gathering system for crude petroleum, whether by pipeline or by truck.
(b) The persons covered by Subdivision (3), Subsection (a) of this section do not include persons transporting only crude oil from property in which they own an operating interest.
(c) The operation of a crude oil gathering system by a person, association of persons, or corporation transporting only crude oil from property in which it owns an operating interest shall not be considered to be included in Subdivision (4) of Subsection (a) of this section.