Oil explorer Caza Oil and Gas said it has terminated its farm-out and exploration deal with Clayton Williams Energy Inc by mutual agreement.The companies had agreed to develop land in Texas owned by Clayton Williams but Caza has pulled the plug on the deal, citing a lack of appropriate return to its shareholders as the motivation.The oil explorer said that the original agreement with Clayton Williams represented a transaction and with potential to transform the company, tripling its current net leasehold position, but the terms of the deal were no longer financially viable."We sought to reach agreement on revised terms to reflect prevailing economics, this was not possible and the decision was taken to terminate the agreement rather than incur further costs and commitments," said group chief executive Michael Ford.Caza shares were down 8.51% to 5.38p at 13:28 on Thursday.