Structural Design of Fixed Jacket-Type Offshore Platforms – A Disruptive Technique

Abstract This paper presents a semi-empirical method to automatically configure, size and carry out the preliminary design of a fixed offshore platform considering only a few basic input parameters when topside details are unavailable. Input parameters include the water depth, maximum wave height, design seismic coefficient, functional type of the offshore platform, a rough estimate of the gross topside weight (other than the structure), the number of well conductors and the available information on piles axial capacity. The main objective of the present work is to create a design and produce material take-off (MTO) that is sufficient for tender documents. The computer program developed for the above purpose generates a detailed analytical model incorporating available knowledge on equipment layout and structural design. The program creates a design without actually carrying out any structural analysis and generates the MTO based on the model created by the program. Structural design of real-life offshore platforms generally passes through several changes during the course of preparing a final design. The most common changes occur due to the requirement of additional deck space identified during model reviews, major revision in equipment layout and detailed material handling studies. In some cases, structural design is influenced by the equipment layout preferred by the owner/operator. The method adopted here will minimize, if not eliminate completely, the subsequent changes in the structural details unless a significant change in the topside facilities is encountered. As expected, a number of different structural designs can exist for the same input data. The most important advantage is the immediate availability of the structural analytical model for subsequent detailed analyses and initiates a 3D model for other engineering disciplines to build up equipment, piping, utilities, etc.