Drilling Facility Design – “ A Wells Up Approach ”

There are a number of developments where new dry tree platform drilling rigs are specified. In some cases the geographical location, number of wells to be drilled and the ongoing life of field intervention requirements lead to the need for a permanent rig installation. The majority of permanent offshore rig installations has in the main been confined to the N. Sea region. As a result there is a significant experience base related to how the rig interfaces with the production platform and the lessons learned from operations that can be used to ensure appropriate drilling facilities are designed. Compared to the overall project or field development cost the initial capital cost of the rig is usually a relatively small proportion of the project. However, when the operational cost of drilling and maintaining the wells is included it can account for between 30 – 40% of the overall development costs. Therefore the actual operational efficiency of the rig will have a significant impact on the overall project economics. During the initial stages of a project it is essential that the project requirements such as the regulatory requirements, well designs, platform interfaces and philosophies and the appropriate levels of mechanisation are understood. This allows a clear definition of the rig equipment selection and functionality to ensure the rig is not over or under rated in order to allow the drilling team to provide a rig that delivers the expected operational efficiency.