Advanced Mud Removal Intervention in an Extended-Reach Well Using Integrated Chemical–Mechanical Design and Real-Time Oversight

Abstract Extended reach drilling (ERD) interventions amplify challenges in wellbore cleaning and fluid placement, particularly across long horizontal open-hole intervals with narrow diameters and reactive mud systems. These challenges become critical when conventional treatment fluids can react with residual drilling fluid components to generate hazardous byproducts, including sour gas. This paper documents a mud removal intervention in an ERD well featuring a 6.125-in internal diameter (ID) and an approximately 5,000-ft open-hole interval at ~7,800-ft TVD and a horizontal displacement exceeding 19,000 ft. A tailored approach combined mechanical conveyance enhancement (2.875-in coiled tubing, hydraulic extended-reach assistance, and friction management additives) with a customized acidic blend engineered to dissolve mud residues while mitigating sour gas-generation risk. The treatment system was qualified through laboratory testing for stability and compatibility under expected downhole conditions. Execution was supported by real-time monitoring and satellite-enabled coordination between field and technical teams. The intervention treated the open-hole interval from +22,000 ft to +27,000 ft MD, achieving 86% placement coverage versus a 90% simulated target. Post-job indicators demonstrated significant mud dissolution and improved well behavior while maintaining operational safety. The case provides a practical benchmark for ERD mud removal using integrated chemical–mechanical strategies and real-time quality control.