Okla. Stat. tit. 52, § 100

The Commission may cause depositions of witnesses residing within or without the state to be taken in any proceeding pending before it in any manner provided by law for taking depositions in civil actions in courts of record; and any deposition so taken shall be sealed up and endorsed with the title of the cause and the name of the officer taking the same, and by him addressed and transmitted to the Secretary of the Commission, where it shall remain under seal until opened by the Secretary on order of the Commission, or at the request of a party to the proceeding, or an attorney for such party.