Tex. Nat. Res. Code § 85.062

The commission and its agents and the attorney general and his assistants and representatives may examine the books and records of a person who produces, stores, transports, refines, reclaims, treats, markets, or processes oil or gas or the products of either as often as considered necessary for the purpose of determining the facts concerning matters covered by Sections 85.058 through 85.061 of this code.