Improving Cement Log Response Through Sandblasting

Achieving reliable cement-to-casing bonding remains a persistent challenge, particularly in wells where microannulus is observed in cement evaluation logs. In the Caspian region, repeated occurrences of microannulus in 7 in liners prompted a focused investigation into surface preparation techniques and their effect on cement bonding. Despite optimizing cement design and mud removal improvements, dry microannulus – approximately 10 microns wide – continued to appear, despite prior optimization efforts. To identify the root cause, a field trial was conducted comparing factory-coated and sandblasted liners placed in sequence within the same well. This allowed direct evaluation of bonding performance under identical downhole conditions. Results from ultrasonic logs demonstrated a clear improvement in bonding across sandblasted sections, while coated joints consistently showed dry microannulus. These findings suggest that liner surface condition plays a critical role in bond quality. The combination of sandblasting with other best practices and job design measures proved effective in mitigating microannulus and enhancing zonal isolation.