In addition to wells that were producing at the effective date of the assignment of the royalty interests to the Trust, SandRidge, pursuant to a development agreement with the Trust, is obligated to drill, or cause to be drilled, the equivalent of 123 development wells, determined by reference to SandRidge's net revenue interest in a well and the perforated length of the well, in an area of mutual interest by December 31, 2015.