CASE Study: Enhancing CBL Quality through Emphasizing on Cementing Best Practice and Expanding Agent System

Abstract

Zonal isolation is an important thing to acquire good cement integrity. One of many ways to evaluate this is by running Cement Bond Log (CBL). Well condition prior, during, and after cement placement contribute high impact on the result of CBL. Aside from that, temperature and pressure changes also give significant outcome to CBL result. In this paper, some improvements wereapplied and the logging results showed significant impact on zonal isolation compare to previous well. Objectives of this paper include improvement applied on case studies to obtain good zonal isolation and no remedial cementing required, emphasizing on applied cementing best practice recommendation, and introducing expanding agent in order to recover micro annulus. Well integrity is a vital element to have long well life cycle. The paper describes the enhancementfrom poor zone isolation in previous well to be better in next well and this became one of best practices of cementing design and execution for Operator. Improvement in mud removal was done by adding spacer volume with high concentration of turbulent spacer. Cement slurry had expanding agent in the system and smart retarder which provided better compressive strength. Improvements in cement system were seen in faster compressive strength build up and ability to recover micro annulus. Linear expansion result from expanding test is 80 μm in 7 days, which is sufficientto cover micro annulus that has happened before in previous well. The designed slurry was also supported by using more centralizers in execution. Quality check was done by measuring rheology of drilling mud and spacer. Cementing job was executed with no issues and following job program. Evaluation of cement job supported with the playback pressure data. Result of CBL result showed that good bonding was achieved on upper and lower side of interest zone.