Trajectory Optimization for Offshore Wells and Numerical Prediction of Casing Failure Due to Production-Induced Compaction

摘要

In the past, trajectory optimization of a wellbore referred to the design of a well path, including a preferred geostress direction and fault structure, to maximize the.penetration rate. This paper considers additional parameters during the trajectory optimization process: pore pressure depletion history, creep property of rocks, and interaction between rock and casing during petroleum production. After considering these additional parameters, a wellbore trajectory can be designed that will be easier to drill and will ensure the longevity of casing utility. A numerical example of casing and wellbore trajectory design in the Ekofisk petroleum field was performed to evaluate the suitability of this trajectory design technique. Seabed subsidence was simulated at the global level with a full field perspective, and casing failure was calculated at a secondary submodel level at the reservoir scale. Inelastic-visco deformation of the reservoir and fluid flow in porous media was calculated. Three sets of numerical results were analyzed to select the optimal wellbore trajectory. The primary submodel and secondary submodel were balanced during the optimization process such that a fine mesh can be adopted for casing failure prediction within the background of the field scale phenomenon.