Permian Basin Royalty Trust is an express trust. Its Waddell Ranch Properties has mineral interests in the Waddell Ranch. Its Waddell Ranch Properties have proved reserves in six fields: Dune, Sand Hills (Judkins), Sand Hills (McKnight), Sand Hills (Tubb), University-Waddell (Devonian) and Waddell. The Waddell Ranch properties contain approximately 918 (net) productive oil wells and 111 (net) productive gas wells. The Blackbeard Operating, LLC is an operator of record of the Waddell Ranch properties. In the six fields, there are 12 producing zones ranging in depth from 2,800 to 10,600 feet. The prolific of these zones are the Grayburg and San Andres, which produce from depths between 2,800 and 3,400 feet. Also productive from San Andres are the Sand Hills gas field and the Sand Hills oil field, the Dune (Grayburg/San Andres) oil field, and the Waddell (Grayburg/San Andres) oil field. The Dune and Waddell oil fields are productive from both the Grayburg and San Andres formations.