Hydraulic Effects of Drill-String Tool Joint and Rotation on Annular Flow Profile and Frictional Pressure Loss Using ANSYS-CFX

In oil and gas well drilling, inaccurate estimation of drilling parameters can affect the predictions of annular flow profile and frictional pressure loss along the wellbore which can result in hole problems, such as hole erosion due to high annular fluid velocity, and inadequate drill cuttings transport, well control issues such as kick or lost circulation. Drill-string tool joints alter the annular geometry, when coupled with drill-string rotation, they affect the annular flow profile and frictional pressure loss by causing turbulence, fluid acceleration/deceleration or changing the drilling mud apparent viscosity. As the oil and gas industry moves towards deeper wells, drilling operation uses more drill-string tool joints, the additional frictional pressure loss can be significant, up to 30% of the total frictional pressure loss. Therefore, there is a need to better understand the effects of drill-string tool joint and pipe rotation on annular flow profile and frictional pressure loss. The objective of this study was to analyse individually and collectively the hydraulic effects of drill-string tool joints and rotation on annular flow profile and frictional pressure loss. The scope and methodology of this research involved Computational Fluid Dynamics (CFD) approach, with ANSYS-CFX (in ANSYS 15) as the analysis system, where a CFD model with an optimum mesh size was created and validated against previous experimental data, where frictional pressure loss values were compared.