Slim Well Casing Design for a Deepwater Application Using a Fast and Flexible Finite Element Engine

Abstract

In the exploration and production (E&P) industry attempts at reducing the cost of the well construction by applying various well architecture slim designs has attracted attention from operators for decades. The recent industry downturn has further contributed to a renewed focus on this strategy. In this study we present a slim well design application within the FortunaCo project (a Joint Venture between OneLNG and Ophir), which aims at developing the Fortuna and Viscata fields in Deepwater offshore Equatorial Guinea. An advanced static nonlinear Finite Element engine is used in this process, which considers contact and friction; can handle large deformations and is therefore suitable to carry out buckling analysis. The top hole structural robustness is analyzed using this engine in the event of a worst case axial load, which for this study is assumed to be:The Conductor Pipe (CP) able to take its own weight only,The upper section of the surface casing (inside the CP) free of cement,The full buoyant weight of the Horizontal Christmas tree and Subsea Blowout Preventer applied onto the well. This paper demonstrates that the selected numerical model is suitable to estimate critical buckling loads and identify post-buckled modes exerted on surface structural casings. Furthermore, it is shown that the visualization capabilities and speed of the engine allow the operator to optimize the design iteratively in an efficient manner. We conclude that the selected methodology is suitable for the operator to validate a slim well design for a Deepwater development application at concept phase for minimal cost with the necessary level of confidence.