USING METAMODELS TO PREDICT CUTTING FORCES IN BOP

Resumo

Cutting drill string inside BOP (BlowOut Preventer) may be required if Dynamic Positioning System
fails to maintain an offshore drilling platform at a fixed point in the ocean. The required force to cut the string is
traditionally determined by analytical models and commissioning tests, which can be far from the real situations.
Depending on boundary conditions of this tubular, the BOP may fail to cut it, which can lead to catastrophic events.
In this way, the proposed work aims to define a metamodel to predict required forces for BOP to cut API S-135
6.63’’ 40.87 ppf drill pipes, with different boundary conditions. Simulations were performed using FEM, with
material and failure modelled according to Johnson-Cook model (1986), with parameters obtained from literature.
Different simulations in combined conditions, including initial traction and torque, pipe decentralization and ram
offsetting, were performed in order to find the required force in indentator to cut the pipe. Such data were used to
develop a metamodel using feed a machine learning algorithm and its results were validated with real test data.
Situations with more realistic boundary conditions concludes that current BOP cutting models may underestimate
the required force.