Japan Oil Development Company (JODCO) has been operating several oil fields jointly with Abu Dhabi National Oil Corporation (ADNOC) in the U.A.E. since the 1970's. The first application of horizontal well technology in the U.A.E. was in 1989. Since then the types and use of horizontal wells have changed very much owing to drastic improvements in horizontal drilling methodology. The reservoir application of horizontal wells is categorized into three types: peripheral locations, crestal locations and in low permeability areas. The objectives of horizontal wells may vary from one to the other. This paper describes the types and the use of horizontal wells during the process of optimization of a full field development plan.