Texas Supreme Court Deems Continuous Development Clause Ambiguous

In Endeavor Energy Resources, L.P. v. Energen Resources Corp. et al. the Supreme Court of Texas construed a continuous development clause in an oil and gas lease covering 11,300 acres in Howard County. After the primary term, lessee Endeavor could retain acreage by drilling a new well every 150 days. The clause gave Endeavor " ... the right to accumulate unused days in any 150-day term during the continuous development program in order to extend the next allowed 150-day term between the completion of one well and the driling of a subsequent well.

After the primary term, Endeavor drilled 12 wells that extended the lease. Endeavor began drilling a 13th well 320 days after completing the preceding well. In the ensuing period Energen top-leased the supposedly non-retained parcels. Litigation ensued.