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Abstract The wells 30/07a-R1 and 30/07a-R4 in the Judy field are the longest extended-reach wells in the United Kingdom (UK) portion of the North Sea and among the longest in Europe. This paper presents the primary challenges and solutions for ERD wells to reach undeveloped structures in existing fields. It shows the utilization of a system's approach to model and manage unique challenges such as high temperature conditions, depletion, and wellbore position uncertainty in horst structures. The offset wells analysis, detailed planning, and successful execution of these wells, including contingency scenarios for undesirable downhole conditions and lessons learned are described. Multidisciplinary interaction was employed to develop strategies to minimize key risks, overcome difficulties encountered during well construction, and learn lessons to address these challenges. A comprehensive engineering analysis of the mechanical, hydraulic, and electrical loads, as well as the temperature and geomechanics constraints, provided insights into past well events. This allowed for evaluation of various hole size and casing alternatives, leading to the selection of the lowest-risk well design configuration. This was crucial in areas where previous wells experienced issues such as wellbore instability, stuck pipe, losses, high temperature, and barite sag. Properly calibrated models, fit-for-purpose practices, real-time monitoring, and optimization were critical to identifying and managing drilling hazards, equipment limitations, and wellbore position uncertainty in the 12¼ in. hole and the 8½ in. lateral. Well 30/07a-R1 was drilled in 2022, reaching a total depth of 29,864 ft at a true vertical depth (TVD) of 12,491 ft. Well 30/07a-R4 was drilled in the first half of 2025, reaching 29,451 ft at 12,475 ft TVD. Both wells are the longest extended-reach wells in the UK portion of the North Sea, nearing the worldwide extended-reach drilling (ERD) envelope boundary. The 12¼ in. sections are among the longest globally, with total lengths of 18,280 and 19,049 ft, respectively, at an inclination of 69-70 degrees while navigating a narrow equivalent mud weight window. The 5,324 and 4,173 ft laterals were successfully drilled by managing the impact of high temperature on downhole tools while achieving wellbore positioning objectives at the reservoir. Extensive modelling in the 30/07a-R4 lateral provided alternative solutions to manage depletion uncertainty in the upper reservoir interval, facilitating successful drilling, liner running, and cementing without losses.