One of our core activities is the design and deployment of exploration and production wells. Since the technology in this area is advancing and therewith the variety of possible well designs it is of paramount importance to re-assess our well design methodology. This paper explains, in concept, the system components and their relationship in performing a well design in a systematic manner. This will provide optimisation of the design as well as providing an audit trail for future performance assessment of the well design. The business aspect and the management of the execution phase will be briefly touched upon in relation with the well design as a basis for technical terms and conditions of a contract as well as Quality Control during the execution phase.