This paper presents a new approach associated with the gas separation in inclined gas-liquid flow. This type of flow is found when gravitational gas separators are applied in association with the submergible centrifugal pump (SCP) technique for oil production in directional wells. Free gas in the suction of the SCP is one of the most important limitations in the design of the pumping system. The purpose of this study is the phenomenological modelling of total gas separation in a gravitational gas separator formed by an inclined annular channel whose geometry is known as inverted-shroud separator. Inclination angle, inlet and outlet gas mass flow rates, position of the dynamic level of liquid in the annular channel, casing pressure, and liquid flow rate are related to the separation efficiency. Bubble size is a key factor for the design of gravitational gas separators. Thus, a correlation for the two-phase turbulent kinetic energy dissipation, which has a significant effect on the bubble size, is proposed. New data were collected in an inclinable test section, at 15 and 45 degrees from the horizontal, with inside and outside diameters of 20 and 65 mm, respectively. The total length of the test section was 10.5 m. Air and water at near atmospheric pressure constituted the gas and liquid phases. The liquid flow rate was in the 9-26 1/min range and the average inlet gas mass flow rate was 1.18 kg/hr. The proposed model was qualitatively compared with data from the literature and quantitatively adjusted against the new experimental data, with good agreement. This new approach will assist in the optimization and sizing of the pumping system for oil production in directional wells. Copyright 2010, Society of Petroleum Engineers.