A New Model to Determine the Two-phase Drilling Fluid Behaviors through Horizontal Eccentric Annular Geometry, Part B: Frictional Pressure Losses Estimation

Abstract

Drilling with aerated muds is becoming more often used in underbalanced drilling operations. One of the major challenges that has to be faced in such operations is the estimation of the physical behavior of aerated fluids inside the annulus. In this study, experiments have been conducted at METU Multiphase Flow Loop using air-water mixtures with various in-situ flow velocities of 0–120 and 0–10 ft/s, respectively. This study aims to develop a model to estimate the frictional pressure losses for two-phase flow through horizontal eccentric annular geometry. In order to estimate the frictional pressure losses, three different methods were developed: (i) definition of new friction factors by using experimental data; (ii) modification of Lockhart-Martinelli pressure loss correction factor; and (iii) modification of Beggs and Brill model by changing the equation constants. The comparison of the developed models with experimental data has shown that frictional pressure losses can be estimated with a reasonable accuracy.

Keywords:

• Beggs and Brill model
• frictional pressure losses
• horizontal eccentric annuli
• Lockhart and Martinelli method
• two-phase flow

NOMENCLATURE

	=	wellbore diameter, L
	=	drillpipe diameter, L
	=	hydraulic diameter, L
	=	slip void fraction of liquid in two-phase flow (liquid hold up)
	=	gas superficial Reynolds numbers in two-phase liquid and gas flow
	=	liquid superficial Reynolds numbers in two-phase liquid and gas flow
	=	mixture Reynolds number in gas-water two-phase flow
	=	liquid superficial velocity, L/t
	=	gas superficial velocity, L/t
	=	Lockhart and Martinelli (1969) parameter in two-phase flow
	=	non slip void fraction of liquid in two-phase flow
	=	liquid density, m/L3
	=	gas density, m/L3
	=	non slip mixture density in air-water two-phase flow, m/L3
	=	liquid viscosity, m/(L t)
	=	gas viscosity, m/(L t)
	=	non slip mixture viscosity in air-water two-phase flow, m/(L t)

Additional information

Funding

The authors gratefully acknowledge TÜBİTAK (The Scientific and Technological Research Council of Turkey) for funding the project through Grant No. 108 M 106. Thanks are also due to the Middle East Technical University (METU) for partial support of this project.