The Abrado Medusa section-milling technology, which allows for full stabilization while milling at extended reach, offers an additional cost-effective solution for operators to address the challenge of permanent abandonment of wells and isolation of formation hydrocarbons. Conventional section mills are limited in sweep diameter, and milling at extended reach is further complicated by a lack of effective stabilization. The Abrado Medusa is a fully self-stabilized technology that enables successful extended-reach milling, including milling through a number of casing strings, whether centric or eccentric, without damaging the outer casing. The ability to create window sections of longer lengths through multiple cemented casing strings regardless of depth enables placement of a competent cement barrier, ensuring formation isolation at or near the reservoir interface or source of migrating hydrocarbons. The fully stabilized milling system has been used to create windows in casings as small as 7 in. up to 185/8 in. in diameter while cleaning or underreaming casing sizes up to 30 in. Successful window lengths in excess of 240 ft, and well deviations above 60°, have been achieved. Operators have been able to place a confirmed cement barrier to block the flow paths of migrating hydrocarbons in wells previously unable to be abandoned using conventional milling equipment.