Title: Modelling of pressure drop in eccentric narrow horizontal annuli with the presence of cuttings and rotating drillpipe

Authors: Titus N. Ofei; Sonny Irawan; William Pao

Addresses: Petroleum Engineering Department, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 31750 Tronoh, Malaysia ' Petroleum Engineering Department, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 31750 Tronoh, Malaysia ' Mechanical Engineering Department, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 31750 Tronoh, Malaysia

Abstract: Accurate pressure drop estimation is vital in wellbore hydraulic design. The present study investigates the effects of diameter ratio, fluid velocity, fluid type, fluid rheology and drillpipe rotation speed on pressure drop in eccentric horizontal wellbore with the presence of cuttings using computational fluid dynamics (CFD). The drillpipe is positioned at eccentricity of 0.623 and rotates about its own axis at 80 rpm and 120 rpm. The diameter ratio varies from 0.64-0.90. Results show significant increase in pressure drop with increasing fluid velocity and diameter ratio. Increase in drillpipe rotation speed from 80 rpm to 120 rpm shows insignificant effect on pressure drop for both Newtonian and non-Newtonian fluids. Non-Newtonian fluid exhibited large pressure drop compared to Newtonian fluid especially at low fluid velocities. Fluid rheology effects are also discussed. Experimental data confirmed the validity of the current model setup with a mean percentage error of 0.84%. [Received: April 03, 2013; Accepted: June 04, 2013].

Keywords: computational fluid dynamics; CFD; diameter ratio; eccentric horizontal wellbore; pressure drop modelling; Newtonian fluids; non-Newtonian fluids; cuttings; rotating drillpipes; wellbore hydraulic design; fluid velocity; fluid type; fluid rheology; drillpipe rotation speed; annular wellbores; oil and gas industry.

DOI: 10.1504/IJOGCT.2015.066931

International Journal of Oil, Gas and Coal Technology, 2015 Vol.9 No.1, pp.39 - 60

Received: 05 Apr 2013
Accepted: 04 Jun 2013
Published online: 18 Mar 2015 *

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