Many fields on the NCS are in a mature stage, and experience narrow and uncertain drilling windows, due to depleted and/or pressurized reservoir zones. This limits options for new infill wells and increased recovery. Further development of Managed Pressure Drilling (MPD) from floating drilling units is necessary to ensure sustainable utilization of the petroleum resources. Open water drilling will increase the safety, efficiency, and operational water depth for offshore drilling, with a wide range of cost and labour savings related to the vessel and equipment, and improved pressure control. The method also opens the possibility to drill with a dynamically positioned rig at shallow water, where the rig offset is particularly challenging during traditional drilling with a marine drilling riser. With two derricks, there are opportunities for parallel activities and significant efficiency gains. Open water drilling has not yet been adapted for drilling of hydrocarbon reservoirs with a blowout preventer (BOP) in place. Equipment limitations, primarily a reliable Rotating Control Device (RCD) has been the main obstacles. The drilling technique eliminates the drilling riser, which allows for new drilling vessel solutions that can reduce equipment and vessel costs and provide operational benefits, which will increase the drilling efficiency. Current drilling and well simulation tools do not incorporate the unconventional configurations required to perform simulation and analysis of open water drilling. The project shall adapt and extend the already existing advanced hydraulic, mechanical, and thermodynamic models developed by NORCE (former IRIS / Rogaland Research) over the last decades. Different cases will be run, with sensitivity analysis of operating parameters. The project will also address the detection and handling of abnormal situations. New possibilities, such as reverse circulation for drilling horizontal sections of the well will also be investigated.
The objectives of the research task are to provide input for the operation and sizing of open water drilling systems and associated equipment through system and well simulations and sensitivity analysis of operational parameters for selected drilling scenarios.
The cornerstone in the research activities is the drilling simulator from NORCE. Although the simulator has been developed over the last 15 years and is state-of the-art in terms of capabilities and level of detail, several adaptions and modifications must be developed due to the level of innovation and unconventional methods in the concepts to be analysed.
Project results will be implemented in the further system development and will be an important design basis for a Pilot Project as the next step. The analysis will be particularly beneficial for the mud return system design.