Leak Identification Revolutionized: A Cost-Effective, Paradigm-Shifting Approach using Coiled Tubing and Distributed Temperature Sensing (DTS)—A Case Study from North Kuwait
Authors: Al-Hamad Hamad , Slama Mohamed Hedi , Al-Naqi Meqdad , Badrawy Kareem , Ayyad Hazim , Al-Matar Mohammed , Al-Sabee Ali Q , Ramondenc Pierre , Sunagatov Rustem , Sebaih Mohannad Adel , Fajardo Sergio Rondon , Al-Oumi Abdul-latif Waleed , Al-Roudan Ahmed , Nicolas Ghassan 
Published: February 2025

The relentless pursuit of well integrity is a critical mission in the oil and gas industry, especially in mature fields where the risks of casing leaks loom large. This study from Kuwait highlights the necessity of constant vigilance to proactively tackle these leaks, which threaten both production efficiency and environmental safety. Emphasizing early leak detection, this research aims to demonstrate how advanced methodologies can significantly reduce the costs and risks associated with extensive workover operations and the potential need for well suspension or abandonment. The focus lies in accurately identifying and quantifying casing leaks, including their depth and directional flow, crucial for effective well diagnostics and integrity management.

This study introduces a cutting-edge approach for pinpointing casing leaks in wells, especially those with simpler completion designs. It showcases the deployment of an optical fiber-enabled coiled tubing system to implement distributed temperature sensing (DTS). This innovative combination enables real-time downhole measurements, including pressure and casing collar locator (CCL) readings for precise depth determination. The key advancement here is the ability to capture temperature anomalies in real-time, offering a comprehensive and dynamic profile of both the borehole environment and the surrounding formation. This approach represents a significant leap forward in well diagnostics technology.

In a North Kuwait oil-producing well with a deviated trajectory, conventional production logging tools (PLT) were inadequate in locating a casing leak. Utilizing well hydraulics analysis, the DTS technology, facilitated by fiber optics-equipped coiled tubing, was employed. Different operational stages were correlated through a series of DTS surveys, ultimately leading to the successful identification of the leak. Notably, this operation was performed without a rig, incorporating a novel nitrogen injection workflow to stimulate leak production. This approach, a first of its kind, marked a shift in industry practices. The precision of this Coiled Tubing and fiber optic system in detecting temperature variations at the influx point was unprecedented, showcasing the method’s effectiveness.

This case study offers invaluable insights into leveraging DTS in conjunction with Coiled Tubing for diagnosing completion leaks. The innovative strategy of nitrogen injection via the annulus of the kill string, enhancing fluid column visibility and inducing wellbore production, while simultaneously monitoring temperature shifts, represents a significant breakthrough. This approach not only confirms the leak location with enhanced accuracy but also adds a new layer to the standard DTS protocol. It sets a new benchmark for industry practices in leak detection and well integrity assurance.