Numerical Modeling of Conductor Casing Installation: Leveraging the Material Point Method

Abstract Objective The tophole sections are critical for well stability, providing support to the well structure, preventing shallow fluid influx, and protecting against formation collapse. This paper aims to simulate the conductor casing installation by driving in offshore clayey soils, by developing a numerical model using the Material Point Method (MPM). The model is validated against operational data to ensure its applicability in predicting the behavior of soil-structure interaction under severe offshore conditions. Methods A clayey soil from the Campos basin, eastern Brazil, is characterized by in-situ CPTu data and modeled using the Mohr-Coulomb criteria. A 2D axisymmetric model with a non-structured triangular mesh and a two-phase single-point explicit formulation is employed to simulate the soil in undrained condition. The casing tubular, described as a rigid body, interacts with soil through an adhesive contact algorithm. A moving mesh procedure ensures the integrity of the mesh near the casing’s external surface. The simulation includes both the self-weight penetration phase and subsequent impact driving. Observations The case study presented refers to a 58.8-m. section of conductor casing, with 36-in. outer diameter and linear weight of 3470 lb/ft. It reached approximately 10 meters in 5 seconds during the self-weight phase, with further penetration during impact driving. The soil is described by a 60 m thick domain consisting of four clayey layers. The depth behavior over time was analyzed by monitoring the conductor tip during soil penetration. The numerical model demonstrated a strong correlation with actual operational data, accurately predicting displacement and stress distributions around the conductor. Soil resistance increased with depth, stabilizing the penetration rate. The Material Point Method proves effective in modeling large deformation problems involving contact mechanics, providing valuable insights into the soil-conductor interaction. Novel This study introduces an approach to modeling conductor casing driving in offshore environment, addressing large deformation challenges and providing accurate soil stress estimations. Calibration with operational data ensures its applicability in predicting soil-structure interaction behavior, allowing for the simulation of different installation scenarios. These findings contribute to optimizing operating parameters, reducing execution time, and enhancing safety, offering significant advancements to offshore geotechnics and well design practices.