The Shenandoah development in the deepwater Gulf of Mexico represents one of the first commercial applications of 20,000-psi technology for high-pressure/high-temperature reservoirs in the Inboard Wilcox trend. From sanction to first oil and achieving 100,000 BOPD within 75 days of first production, the project demonstrates how advanced subsea systems, floating production infrastructure, and specialized production chemistry enable reliable development of ultra-deep reservoirs at ~30,000-ft depth. The presentation highlights lessons learned in project management, flow assurance, corrosion control, and scale management for next-generation HP/HT offshore developments.