Well integrity possesses major challenges for field operators all over the world. A packer leak is common amongst many other well integrity issues especially for old well. One well in South China Sea was diagnosed with ultrasonic and temperature logging and proved to have such problem forcing the field operator's to shut in the well due to safety concern as the leak create high tubing annulus pressure. Total production lost was 500 bbl of oil per day. Through tubing wellwork was chosen as preferred option because it is more economical relative to workover particularly for such well in a mature field where reserve was depleted. A multiple through tubing wellwork operations using calcium carbonate and cement design with different strategies and methods had been attempted but results are temporary cure at best. Determine to success, previous work program was thoroughly examined inclusive the slurry recipes. The intervention methods were reviewed and challenged, then later refined. Finally, enhanced and optimized cement slurry is engineered together with different approach of well work in which specifying the requirement for acoustic fluid level monitoring. The packer leak was successfully repaired. This paper will discuss the previous coiled tubing method or approach that was failed, the reasons behind the failure and current work program that prove as successful. The innovative slurry design and best practices will also be deliberated. Introduction An oil and gas producing field is located at 260km from Kerteh, Terengganu. It was first explored in the block in 1971, which then produced its first oil in 1978. The field is located at southeastern part of the Malay basin with average water depth of 70m. The field consists of both gas and oil reservoirs. Currently, the field has two mother platform and 1 satellite drilling platforms which locate all the surface facilities such as oil and gas processing, produced water system, water injection facilities and other utilities system. The produced oil and gas then being transported to the shore via a common crude oil pump platform for oil and to a common gas processing platform (CPP) for gas.

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