TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractThe investigation of cement integrity over life of well conditions continues to be a high priority within the well cementing industry. Increasing awareness of problems associated with cement sheath failure and subsequent loss of zonal isolation or sustained casing pressure have demanded that set cement material behavior and the coupled behavior of casing, cement and formation be more fully understood in order to make rational engineering decisions. Recent advances in wellbore stress modeling can now provide a probabilistic determination of the suitability of a particular cement design for the expected range of induced well stresses. This paper describes the cement evaluation and wellboremodeling methodologies specifically developed to predict the magnitude of tensile or compressive forces created by changing wellbore or reservoir conditions.