Optimizing Underbalance Coiled Tubing Descaling Operations: Leveraging Downhole Telemetry for Operational Efficiency

Abstract Scale accumulation in oil and gas wells presents significant challenges, particularly in low bottom hole pressure environments where conventional overbalanced cleanout techniques fail, risking fluid losses that compromise formation integrity and increase intervention costs. This paper demonstrates how underbalance descaling, enhanced with real-time downhole telemetry, mitigates these risks by minimizing fluid losses, protecting the reservoir, and reducing chemical consumption, water usage, and carbon emissions. Case studies illustrate how this approach reduces well intervention costs while maintaining high operational efficiency. Descaling operations were performed using Coiled Tubing (CT) with a bottom-hole assembly (BHA) tailored for sour well conditions with severe iron sulfide scale deposits. The BHA incorporated real-time telemetry, enabling continuous monitoring of pressure, temperature, torque, tension-compression, and vibration. This data-driven approach enabled: Improved efficiency: real-time insights optimized fluid selection and rate of penetration by monitoring key parameters like tension and vibration. Risk mitigation: downhole pressure monitoring minimized the risk of stuck CT pipes. Reservoir protection: underbalanced conditions prevented removed scale from re-entering the formation, safeguarding integrity. Overall, this methodology significantly improved operational performance, reduced risks, and ensured reservoir integrity and improved environmental and regulatory compliance. The optimization strategy delivered impressive results across six wells (Well-A through Well-F): Fluid consumption: total fluid volume reduced by 20% to 70%, including up to 70% reduction in water usage. Penetration rate and intervention time: penetration rates improved by 200%, reducing intervention time by 66%. Environmental impact: carbon emissions decreased by up to 66%. Cost and safety: lower chemical waste and reduced costs, along with enhanced safety through real-time monitoring. These outcomes highlight the transformative role of telemetry in optimizing descaling operations while reducing environmental and operational risks. This paper introduces a groundbreaking approach to underbalance descaling using real-time telemetry. It addresses challenges in sour wells and low-pressure environments, providing scalable solutions for operational optimization, cost reduction, and environmental sustainability. This approach sets a new standard for efficient and environmentally conscious scale management.