Numerical Study of the Relationship Between Bit Stick-Out and Drill Bit Size in Deepwater Jetting Drilling

Resumo

Jetting is a common technique for conductor casing driving in cohesive soils. This installation method
shows faster results with less cost. However, even nowadays, the jetting operation relies on the experience and
expertise of the drilling team for a successful performance. Therefore, to have a clear picture of jet excavation,
computational fluid dynamics (CFD) approaches have been applied as a safe and economical alternative compared
to field tests. This paper presents a numerical simulation of jetting operation for conductor casing in cohesive soil.
Since the main operation parameters are pump rate, the ratio of bit-to-conductor dimensions and bit stick-out, this
work investigates the relationship between the bit stick-out and drillbits of different magnitude. For simulation of
the soil-jet interaction, a two-phase Lattice-Boltzmann model (LBM) combined with the Volume of Fluid (VoF)

method was used to track interface behaviour. The soil is represented as a viscous fluid and described by Herschell-
Bulkley viscosity model. The model is calibrated for a well in the Brazilian Pre-Salt. Therefore, this study purposes

a follow-up analysis of the jetting process on Brazilian wells to advance understanding of the interaction between
its different parameters and their effect on the operation performance.