Neb. Rev. Stat. §§ 57-229
A severed mineral interest shall be abandoned unless the record owner of such mineral interest has within the twenty-three years immediately prior to the filing of the action provided for in sections 57-228 to 57-231, exercised publicly the right of ownership by (1) acquiring, selling, leasing, pooling, utilizing, mortgaging, encumbering, or transferring such interest or any part thereof by an instrument which is properly recorded in the county where the land from which such interest was severed is located; or (2) drilling or mining for, removing, producing, or withdrawing minerals from under the lands or using the geological formations, or spaces or cavities below the surface of the lands for any purpose consistent with the rights conveyed or reserved in the deed or other instrument which creates the severed mineral interest; or (3) recording a verified claim of interest in the county where the lands from which such interest is severed are located. Such a claim of interest shall describe the land and the nature of the interest claimed, shall properly identify the deed or other instrument under which the interest is claimed, shall give the name and address of the person or persons claiming the interest, and shall state that such person or persons claim the interest and do not intend to abandon the same. The interest of any such owner shall be extended for a period of twenty-three years from the date of any such acts; Provided, that the provisions of this section shall not apply to mineral interests of which the State of Nebraska or any of its political subdivisions is the record owner.
Neb. Rev. Stat. §§ 57-229