Pipe integrity and cement quality evaluation in an Iranian gas-well workover operation by USI-tool logs analyzing

Workover operation is an important part of the petroleum industry after drilling-production operations and their problems in a well. In this work, the USI (Ultra Sonic Imager) tool has been run for casing corrosion detection and cement bond evaluation in southern Iranian gas well. The interval that has been logged is from 3210 to 13.3m. The cement bond quality based on USIT results analysis and cement map is totally inappropriate with channeling, patchy, contaminated and free pipe (no appropriate separation between casing and formation). Nevertheless, from 3082 to 3210m (lower section), the cement quality is perfect and provides good zonal isolation. The CSR (Corrosion Summary Report) demonstrates the casing circumstances are proper, and no critical internal and external corrosion is seen. Furthermore, the metal loss value range is between a minimum 0.98% and a maximum 28.68%. Nonetheless, high metal loss percent might be due to different joints or collars with different thicknesses. The USIT results show that casing/liner corrosion is not in critical condition. Moreover, cement has not appropriated isolation level in some intervals, and thus, to prevent future workover operations, the squeeze cementing job is proposed, and the flow could be from completion string joints in some sections.