Administrators and executors of the estates of deceased persons and the guardians of the estates of minors and incompetents where such estates include lands, or mineral interests therein, leased for oil and gas purposes are hereby authorized, with the approval of the district court having jurisdiction of the estate involved, to enter into agreements unitizing any part or all of such lands or mineral interests with adjacent lands so that the entire unitized tract may be developed and operated thereafter as a unit for the production of oil and gas, or either of them.