Sustainable Well Integrity Remediation in Aging Methane Wells Using Hybrid Coiled Tubing Technology

Abstract The objective of this project was to address well integrity issues in an aging methane production well, completed with a single 300mm casing, which supplies a compressor system for a green-energy-plant. The wells, over 60 years old, featured a 6-meter open hole and had never undergone any interventions, presenting significant challenges due to unknown well construction, casing conditions, and wellbore integrity. The well's methane production is critical for powering the green-energy-plant, which generates electricity, necessitating a sustainable and cost-effective intervention due to the lower ROI compared to traditional Oil&Gas projects. At the same time, the operation required advanced technologies to identify and remediate the integrity issue. A Hybrid Coiled Tubing Technology (HCTT), distinguished by its integration of both electrical and fiber-optic conductors, was deployed to perform a minimally invasive well integrity inspection. This innovative design combines the conveyance and diagnostic capabilities of wireline with the advanced sensing and real-time data transmission features provided by fiber optics. This dual functionality not only facilitates precise intervention but also enables comprehensive, real-time diagnostics, making HCTT an ideal solution for addressing complex well integrity challenges. The real-time video camera, powered continuously by HCTT without battery constraints, enabled a comprehensive analysis of the casing's condition, including leak detection, assessment of casing connections, and evaluation of ovality. Given the critical need to identify a small water leak—despite its minimal size, it was significantly impacting the performance of the compressors at the green-energy plant—a contingency plan was developed leveraging the flexibility of the HCTT. The integrated fiber optics within the HCTT enabled the deployment of Distributed Fiber Optic Sensing (DFOS) to detect temperature anomalies and acoustic signals associated with water ingress. Following the inspection, a customized abrasive scraper BHA and slurry were employed. The slurry was specially formulated to be non-aggressive, yet effective enough to remove the rust and scale caused by prolonged water exposure and casing life, which would have hindered the successful installation of the 13-3/8" patch. The real-time camera inspection, supported by the high-quality HCTT cable, successfully identified and localized the small water ingress. It provided insights into the well construction and assessed the condition of the casings. While DTS & DAS remained part of the contingency plan, their inclusion as back-up was essential to ensure a comprehensive approach. The use of a low-concentration quartz sand mixture in the abrasive scraper process effectively removed surface rust without compromising the integrity of the casing. The 13-3/8" patch was installed with the assistance of a real-time BHA, ensuring accurate inflation and placement. The well integrity issue was solved in just three CT runs, restoring methane production and eliminating water ingress. As a result, the compressor’s performance returned to normal, and the well was successfully handed back to the Operator. This project highlights the application of HCTT for sustainable well integrity remediation in aging methane wells supporting green energy production. The use of real-time data, non-invasive inspection techniques, and an effective contingency plan provided multiple layers of assurance for the intervention. This case demonstrates how advanced well intervention techniques can ensure operational efficiency and sustainability in low-ROI green energy applications, setting a benchmark for similar well integrity challenges.