Precision Milling Solutions: Enhancing Well Accessibility with Robotic E-Line Milling Technology

Abstract Objectives/Scope The primary objective of this operation was to resolve a downhole obstruction in an oil well by milling and enlarging a 2.75-inch nipple, to enhance accessibility and enable the retrieval of a fish stuck below the nipple. This intervention aimed to showcase the effectiveness of advanced robotic e-line milling technology in challenging well conditions. This paper will detail the methodology employed during the milling operation, including the tools and techniques used, and the key lessons learned from the intervention. Methods, Procedures, Process The operation employed a combination of a hydraulic stroking tool, an e-line tractor, and a robotic e-line milling tool equipped with a custom-designed bit. Extensive pre-job testing was conducted to determine optimal milling parameters, including weight on bit (WOB), current signature, and estimated milling duration. The toolstring was deployed in multiple runs, with real-time data guiding adjustments to milling parameters. Pre- and post-milling verification runs using slickline confirmed the effectiveness of the intervention. Results, Observations, Conclusions The nipple was successfully enlarged from 2.75 in. to 2.86 in. inner diameter (ID). The operation required continuous adjustment of WOB based on real-time feedback from the e-line milling tool, ensuring efficient and effective milling. The inclusion of the hydraulic stroking tool proved critical in mitigating stuck-tool scenarios, ensuring safe and efficient operations. The intervention enhanced well access, confirmed by slickline verification runs, enabling the operator to proceed with the fishing operation. This approach eliminated the need for coiled tubing (CT) and heavy-duty surface equipment, minimizing risks, reducing costs, and leaving only fine debris downhole. Novel/Additive Information This operation demonstrates the efficiency and precision of electric-line milling technology for resolving downhole restrictions. It underscores the adaptability of this solution in complex well scenarios, offering a safer, more cost-effective alternative to traditional methods while maintaining high standards of operational performance.