Not considering thermal phenomenon in hydrodynamic models could lead to significant differences in pressure gradient prediction. The study of Heat Transfer in two-phase gas-liquid flow is of particular interest in those systems in which the liquid phase is of high viscosity as in the case of heavy oil. In heavy oil, small variations of temperature change its viscosity significantly, which could substantially modify the flow hydrodynamics affecting the oil production system, including the particular case of horizontal wells where thermal recovery processes are applied. However, the petroleum industry has paid less attention to the study of heat transfer in multiphase flow than to the hydrodynamics of the flow. The first part of this work presents the results of an extensive bibliographical revision of the research carried out in Heat Transfer in two-phase flow without phase change in wells and horizontal pipes. The article discusses current tendencies in the modeling of physical phenomenon, the correlations in order to evaluate the two-phase convective coefficient, studies of specific phenomena and the experimental techniques used. The second part will include the studies of Heat Transfer applied to vertical pipes and annular conduits (Segura et ed., 2003). The bibliographical review shows that in general just a few works exist related to the study of Heat Transfer in two-phase gas-high viscosity liquid flow. This situation is particularly critical in horizontal pipes where very few studies have been published on Heat Transfer in two-phase flow even for the case of low viscosity liquids.
