Correlating Shrinkage Behavior and Transit Time Development in Well Cement for Offshore Wells

Abstract

Understanding cement shrinkage behavior in offshore well cement sheaths is crucial for assessing integrity and preventing potential issues. This study investigates the correlation between early strength development and shrinkage to assist in cement paste design. In this research, one cement paste was formulated with water-to-cement ratio of 0.36 and cured under different conditions, including temperatures of 40 °C, 60 °C and 80 °C, and a pressure of 1.0 kpsi. The development of the cement pastes was analyzed using ultrasonic pulse velocity and volumetric shrinkage tests over a period of 90 hours. By employing specific markers of percolation in each test, the results were synchronized, enabling the correlation of data to better understand the evolution of shrinkage and its relationship to transit time. The results obtained from the experimental testing showed a clear correlation between the normalized evolutions of transit time and cement shrinkage for the 3 testing conditions. The findings of this study allow the practitioner to understand when and how shrinkage will occur, with respect to a routine test, the ultrasonic pulse velocity. The results can feed numerical models of early cement behavior. This will support better decisions about well operations to be performed during the wait-on-cement time and in the following days, improving its performance as a well barrier.