Extension of the Gray Correlation To Inclination Angles

Abstract

Abstract Proper design of gas wells requires accurate estimation of pressure profile. This task is usually carried out by integrating mechanistic models and correlations along the well trajectory. Gray (1975) correlation is widely used for gas wells where the liquid fraction is usually low. This correlation has been generated by extending the single phase gas equation to the two-phase flow case. The effect of the liquid in the frictional pressure gradient has been considered by a pseudo roughness. Also, a correlation for the holdup was proposed by Gray (1975). Unfortunately, these two correlation did not consider the effect of the deviation angle which became critical with the recent increment of horizontal well drilling. This paper aims to include the deviation angle effect on Gray (1975) correlation. Gas-liquid experimental data from horizontal to vertical has been considered for the calibration. The considered experimental data (Guner, 2012; Alsaadi, 2013) includes pressure drop and liquid holdup for a 3-in ID pipe. The calibration has been carried out through the inclusions of new dimensionless numbers. Comparison between the original and modified Gray correlation are also presented.