Okla. Stat. tit. 27, § 16

A. In every case wherein private property is taken or damaged for public use, the person whose property is taken or damaged shall be entitled to just compensation. B. "Just compensation", as used in subsection A of this section, shall mean the value of the property taken, and in addition, any injury to any part of the property not taken. Any special and direct benefits to the part of the property not taken may be offset only against any injury to the property not taken. If only a part of a tract is taken, just compensation shall be ascertained by determining the difference between the fair market value of the whole tract immediately before the taking and the fair market value of that portion left remaining immediately after the taking.