Tex. Natural Resources Code § 86.182: USE OF SOUR GAS.

In addition to the purposes for which sweet gas produced from a gas well may be used, sour gas may be used for efficient chemical manufacturing purposes including the manufacture of carbon black provided:

(1) it is utilized in a plant producing a recovery of not less than one pound of carbon black to each 1,000 cubic feet of gas; and

(2) the gasoline content is removed and saved from the sour gas before the gas is used for carbon black.

Acts 1977, 65th Leg., p. 2539, ch. 871, art. I, Sec. 1, eff. Sept. 1, 1977.