Computational Fluid Dynamics Simulation of High Pressure and High Temperature Waterjet Downhole Drilling Environments for Design of Helix in Drilling Calibration Apparatus

摘要

High pressure waterjet drilling (HPWD) as a cutting-edge upstream technology receives considerable attention in horizontal drilling fields. HPWD technology achieves great commercial benefits for the reentry multilateral well drilling in small diameter space where the conventional rotarydrill bit needs high-cost tools to implement. The sophisticated waterjet downhole drilling environments are difficult to predict because the temperatures and pressures varied with the depth of the well and the chemical compositions of drilling fluid. Different proportion of waterjet drillingfluid (density or viscosity) may produce different pressures and temperatures for the waterjet drilling bit. Therefore, computational fluid dynamics (CFD) simulation of the waterjet drilling environments is of crucial significance, especially for the design of downhole navigation apparatus.This paper describes the design details of helix drilling calibration (HIDC) apparatus with MEMS gyroscope based measurement while drilling (MGWD) device in downhole harsh conditions. The design objective of HIDC apparatus is that the determined errors of MGWD device interrupted by scale factorerrors and axis non-orthogonal errors can be modulated and the stochastic errors and the bias drift of MGWD device can be reduced. The drilling environments of HIDC apparatus are simulated by ANSYS INFLUENT software and the simulation results demonstrate that the temperature, the pressureand the flow rate of waterjet drilling fluid to HIDC apparatus are 172.85 °C, 4×108 Pa and 704.4823 m/s respectively.