Okla. Stat. tit. 68, § 1012

The tax herein referred to shall, at all times, be and constitute a first and paramount lien against the purchaser's or producer's property as the case may be, both real and personal; and the provisions hereof, making the purchaser liable to pay such tax, and the provisions requiring the producer to pay the royalty owner's tax, in no wise releases the producer or purchaser from liability to pay same, in all cases where such tax is not paid. Laws 1963, c. 365, § 2; Laws 1965, c. 215, § 2.