California Code, Public Resources Code - PRC § 3655

(a) A total value, composed of the combined value of all of the primary tract assignment and secondary tract assignment, shall be assigned to all of the tracts of land which are the subject of the unit agreement or the proposed unit agreement.

(b) The pro rata interest of each working interest owner shall be equal to a fraction, the numerator of which shall be the total value of the primary tract assignment and secondary tract assignment of the tract or tracts in which he has a working interest, in accordance with his fractional share of such interest, if any, and the denominator of which shall be the value determined under subdivision (a).

(c) The pro rata interest of each royalty interest owner shall be equal to a fraction, the numerator of which shall be the total value of the primary tract assignment and secondary tract assignment of the tract or tracts in which he has a royalty interest, in accordance with his fractional share of such interest, if any, and the denominator of which shall be the value determined under subdivision (a).

If there are no royalties outstanding with respect to a tract or tracts of land included within or proposed to be included within a unit area, then for the purpose of determining the three-fourths of royalty interests the working interest owners in any such tract of land shall be deemed to be the owners of a royalty with respect to such tract in the same proportion as their ownership of the working interest therein.