Oil production involves significant heat exchange between the wellbore fluid and its surroundings. During production, the hot fluid losses heat to the cold surroundings, continuously as it moves up the borehole. The heat transfer process impacts well-integrity and, in turn, the ability of the well to perform its required function effectively and efficiently whilst safeguarding life and the environment. One often overlooked heat transfer effect is increase in annulus pressure resulting from annular fluid thermal expansion, which can result in tubing collapse or casing burst. Damage due to high annular pressure can dramatically affect the well-integrity. During the design phase of a well, it is necessary to avoid risks and uncertainties and look at its planned life cycle. This study intends to investigate wellbore heat transfer and its impact on the well-integrity. Moreover; the results of the present work can be used for the preliminary design calculation of oil wells to estimate changes in some thermo-physical properties of the annular fluids. This study provides a baseline for temperature related well-integrity problems in oil wells. © 2012 Asian Network for Scientific Information.