Numerical Modelling of Conductor Casing Settlement Using a Two-phase Model

Resumo

Oil exploration in subsea wells is a complex activity that involves a number of technical challenges, including installation conductor casing installation. The conductor casing plays a crucial role in the structural stability and overall performance of the well. Thus, for the conductor sttelemnt, one can highlight, among other techniques, the jetting method. Jetting is a promising technique for clay soils since seabed sediments behave like fine mud. In order to numerically model the operation, the clayay soil can be represented by a highly viscous non-Newtonian fluid.
The aim of this study was therefore to carry out a numerical analysis of the conductor settlement by jetting. In order to achieve the proposed objectives, an eulerian - eulerian two phase model has been adopted. The soil phase has been modelled as a non-Newtonian fluid and computational fluid dynamics (CFD) has emerged as a powerful numerical tool for modeling and simulating problems of this nature in a attempt to bypass the issues that comes with large deformations problems other numerical methods. Ansys Fluent software was used, a CFD program based on the Finite Volume Method (FVM), which stands out for its robustness and precision when carrying out fluid dynamic simulations. The numerical analysis was carried out using the Gidaspow drag model to characterize the soil, which combines the Ergun and Wen-Yu empirical correlations.
The results obtained showed that the excavation of the seabed using the jetting technique is significantly influenced by the velocity of the jet. In addition, other criteria also affect excavation, such as the type of fluid injected and the size of the drill bit.