Enhancing Coiled Tubing Water Shut-Off Operations: Lessons Learned and Best Practices for Zonal Isolation

Coiled tubing (CT) water shut off treatments have been proven as an effective method in reducing water cut in production wells. This paper introducesinnovative design and execution techniques for CT water shut off treatments. It also highlights the importance of candidate and treatment selection for different completions to ensure successful water shut-off operations. Additionally, the paper addresses the ways to optimize water shut-off operations and mitigate all the associated risks. The first method addresses wells completed with Inflow Control Devices (ICDs), emphasizing the necessary precautions to prevent unintended production loss in non-target zones during treatment. The second method focuses on wells with perforated completions and compares its complexity and efficiency with ICD-based designs. Additional completion types—such as screens and open-hole configurations—are also discussed, highlighting the fact that the basic treatment principles remain the same, while the execution complexity varies significantly. The paper also outlines optimal operating procedures and demonstrates how real-time downhole monitoring systems—integrated through both CT and Electrical-Wireline (E-line)—enhance treatment design, volume accuracy, execution control, and post-treatment evaluation. The paper provides insight into how the integration of mechanical and chemical isolation methods with real-time downhole monitoring systems can provide the best solution for operational execution of water shut off in any type of completion. Several observations were made such as the implementation of a pre-treatment logging survey to accurately identify water-producing zones, which can ultimately optimize the treatment volume. Additionally, it is crucial to ensure proper isolation of completion components or downhole mechanical isolation tools to prevent water shut-off treatments from invading other hydrocarbon producing zones. Moreover, the use of an on-location laboratory was critical for optimizing the chemical recipe based on real-time downhole acquired data. Cleanout operations were found to be essential to guarantee the correct setting of mechanical isolation downhole tools and to provide a clear path for fishing tools to retrieve the mechanical isolation tool. The treatment deployment process was concluded using an appropriate bottom hole assembly (BHA), taking into consideration whether upper zone isolation was necessary or not. The downhole monitoring system proved valuable in enabling real-time depth correlations, as well as monitoring downhole pressure and temperature during treatment placement, which were vital for the successful execution of these operations. This paper represents CT innovative design and execution techniques for water zonal isolation in oil and gas wells that can be utilized for maintaining high production levels while reducing the operational cost of these wells. Moreover, it provides a clear path to rig-less water shut-off solutions.