Perpustakaan Digital ITB

This study investigates the fracture behavior of cement sheaths under increasing bottom hole pressure (BHP) using a three-dimensional finite element approach. The model simulates stress-strain response and crack development in a cemented casing system embedded in tight sandstone. Three distinct stress regimes—normal faulting, strike-slip, and reverse faulting—were modeled to represent realistic variations in in-situ stress conditions. Results show that compressive stress is the primary driver of mechanical failure, particularly when the stress exceeds the cement's ultimate strength. Among the three regimes, reverse faulting exhibits the highest resistance to failure due to greater lateral confinement, while normal faulting leads to earlier fracture initiation. Crack propagation is most prominent around perforation zones, following the concentration of lateral confinement stress and displaying different orientations depending on the dominant stress field. The overall findings confirm that the cement sheath behaves as a brittle-elastic material, and that stress regime plays a pivotal role in determining fracture onset and pattern. These insights are relevant for improving the design and evaluation of well integrity under hydraulic loading scenarios.