Session: 11-02-01 Well Drilling Fluids & Hydraulics

Submission Number: 157389

Helical Flow of Yield-Viscoplastic Fluids in Concentric Annuli 

Helical flow in an annulus is a case of both practical and theoretical relevance. Such flows occur for example in separation processes, journal bearings of rotating machinery and when drilling wells for accessing sub-surface geological structures.  Most drilling hydraulic models are designed for purely axial flow due to the added complexity of flow with a rotating drill string. Rotation is either accounted for using some empirical correlations or tackled using CFD models.  However, when the annulus is concentric, the problem simplifies considerably, and a relatively simple numerical solution is available, valid both for Newtonian and for inelastic non-Newtonian fluids.  In addition to the effect of the string rotation rate on the axial pressure drop, the solution also gives the resulting string torque as well as the cross-sectional profiles of axial and tangential velocities and any presence of a unsheared plug region.  After the first publication of this solution by Coleman and Noll [1], there are very few publications in the engineering literature which have explored this solution, one exception being the work of [2].  However, they only presented results for pressure loss, but not for the velocity profiles.

Here we revisit this solution, with a specific focus on Herschel-Bulkley type fluids where the shear thinning properties result in a reduction of pressure loss with increasing rotational speed. The novelty of this work will be an empirical correlation for the pressure loss reduction as function of rotational speed, based on the numerical model, in addition to velocity profiles. Results will be presented in terms of dimensionless quantities like Reynolds number and Taylor number, within the range of hydrodynamically stable flow.

[1]          Bernard D. Coleman, and Walter Noll, 1959, “Helical Flow of General Fluids,” J. Appl. Phys., 30.

[2]          Ramadan Ahmed, and Stefan Miska, 2008, “Experimental Study and Modeling of Yield Power-Law Fluid Flow in Annuli with Drillpipe Rotation (IADC/SPE 112604).”

Presenting Author: Bjørnar Lund SINTEF

Presenting Author Biography: Graduated from NTH, University of Trondheim (master degree in physics 1987 and doctoral degree in physical electronics 1992).
Research Scientist/Senior Research Scientist at Rogaland Research 1995-2002 (drilling and well technology).
Senior Research Scientist at SINTEF 2002-current (multiphase flow and drilling and well technology).
Main research interests: liquid-particle flow and non-Newtonian fluids and flow